# Question
Title: What is the longest known 7-piece checkmate?
What is the longest known 7-piece checkmate?

# Answer
549 moves. Here is the link to the Lomonosov tablebase for this special position. This record was generated and discovered in 2014 by Guy Haworth; his publication "Chess Endgame Records" can be found at online..

```
[FEN "1n1k4/6Q1/5KP1/8/7b/1r6/8/8 w - - 0 1"]

1.Kf5 Rb5+ 2.Kg4 Rb4+ 3.Kf3 Nd7 4.Qh8+ Ke7 5.g7 Bf6 6.g8=N+ Ke6 7.Qh3+ Kd6 8.Kg2 Rb2+ 9.Kf1 Rb1+ 10.Ke2 Rb2+ 11.Kd1 Rb1+ 12.Kc2 Rb2+ 13.Kc1 Rb5 14.Qh6 Rc5+ 15.Kb1 Rb5+ 16.Ka2 Ra5+ 17.Kb3 Rf5 18.Ka3 Rf3+ 19.Ka2 Ke6 20.Qh7 Ne5 21.Nh6 Rf2+ 22.Kb1 Rf4 23.Qg8+ Kd6 24.Ka2 Nc6 25.Ng4 Bd4 26.Qg6+ Kd5 27.Qg5+ Ke4 28.Kb1 Nb4 29.Qe7+ Kd3 30.Qh7+ Ke2 31.Qh2+ Kf3 32.Qh3+ Ke4 33.Qg2+ Kd3 34.Qg3+ Ke4 35.Qe1+ Kd3 36.Qd1+ Ke4 37.Qe2+ Kd5 38.Kc1 Kd6 39.Qh2 Nd5 40.Kd2 Bc3+ 41.Ke2 Bd4 42.Qh6+ Kd7 43.Qh7+ Kc6 44.Qg8 Kc5 45.Kd3 Nb4+ 46.Kd2 Nd5 47.Qc8+ Kd6 48.Nh6 Bc3+ 49.Ke2 Re4+ 50.Kf2 Rf4+ 51.Kg1 Bd4+ 52.Kh2 Ne3 53.Qd8+ Kc6 54.Qe8+ Kc5 55.Nf7 Rf2+ 56.Kh3 Rf3+ 57.Kh4 Rf5 58.Nh6 Rf1 59.Qa8 Kb4 60.Kh5 Kc3 61.Qc8+ Kd3 62.Kg6 Rf2 63.Qa8 Rf1 64.Qb8 Kd2 65.Qb3 Ke2 66.Qb5+ Kd2 67.Qg5 Kc2 68.Kh7 Kd3 69.Qb5+ Kc3 70.Qa5+ Kd3 71.Qg5 Rf6 72.Qb5+ Ke4 73.Qb7+ Kd3 74.Qd7 Kc3 75.Qe8 Kd2 76.Qb5 Kc2 77.Qe2+ Kc3 78.Qh5 Rf1 79.Qg6 Rf6 80.Qe4 Kc4 81.Qe8 Kd3 82.Ng8 Rf1 83.Ne7 Rh1+ 84.Kg6 Rg1+ 85.Kf7 Rf1+ 86.Ke6 Rf6+ 87.Kd7 Bc5 88.Nc6 Nd5 89.Nd8 Rd6+ 90.Kc8 Ne7+ 91.Kc7 Nd5+ 92.Kb7 Rb6+ 93.Kc8 Ne7+ 94.Kd7 Nd5 95.Qe1 Rd6+ 96.Kc8 Be3 97.Qd1+ Ke4 98.Qc2+ Kd4 99.Qa4+ Ke5 100.Qh4 Kf5 101.Qh3+ Ke4 102.Nf7 Rc6+ 103.Kd8 Kd4 104.Ke8 Rc7 105.Kf8 Bf4 106.Qe6 Ra7 107.Qe2 Be3 108.Qg4+ Kc5 109.Qc8+ Kd4 110.Qb8 Kd3 111.Kg8 Rc7 112.Qb5+ Kd4 113.Qa4+ Kc5 114.Qa6 Kd4 115.Kf8 Bd2 116.Qf1 Bc3 117.Kg7 Rc6 118.Kg8 Nf6+ 119.Kf8 Rc8+ 120.Kg7 Ne4 121.Qb5 Ke3+ 122.Kh7 Rc7 123.Qb6+ Rc5 124.Qe6 Kf4 125.Qh6+ Kf3 126.Qh3+ Ke2 127.Kg8 Rc6 128.Kf8 Bb4+ 129.Kg7 Bc3+ 130.Kg8 Rf6 131.Qh4 Kd3 132.Nd8 Kd4 133.Qg4 Ke5 134.Qe2 Kf4 135.Qc4 Kf3 136.Qb3 Kf2 137.Ne6 Ke3 138.Qa2 Rf3 139.Qc2 Be5 140.Qd1 Bc3 141.Qc1+ Kd3 142.Nf4+ Kc4 143.Ng2 Rf2 144.Nh4 Nf6+ 145.Kg7 Ne4+ 146.Kg6 Rf6+ 147.Kh5 Kd4 148.Qd1+ Ke3 149.Qb1 Bd2 150.Ng6 Ng3+ 151.Kh6 Bc3 152.Qc1+ Kd3 153.Qg1 Ne4 154.Kh7 Rd6 155.Kg8 Rd8+ 156.Kf7 Rd7+ 157.Ke6 Rd6+ 158.Ke7 Bf6+ 159.Ke8 Rd8+ 160.Kf7 Rd7+ 161.Ke6 Rd6+ 162.Kf5 Rd5+ 163.Kf4 Bg5+ 164.Kg4 Ke2 165.Qa7 Bd2 166.Qe7 Rg5+ 167.Kh3 Ke3 168.Nh4 Rg3+ 169.Kh2 Rg4 170.Qa3+ Bc3 171.Qa7+ Ke2 172.Ng2 Be5+ 173.Kg1 Nd2 174.Qf2+ Kd1 175.Kh1 Bd4 176.Qe1+ Kc2 177.Qe2 Re4 178.Qh5 Nf1 179.Qd5 Nd2 180.Qf5 Kd1 181.Nf4 Be5 182.Qh5+ Kc2 183.Ng6 Bf6 184.Kg2 Bg5 185.Qh7 Kd1 186.Qh8 Be3 187.Qh5+ Kc2 188.Nh4 Bd4 189.Nf5 Be5 190.Qe8 Rg4+ 191.Kh3 Re4 192.Qc8+ Kd1 193.Qc5 Nc4 194.Nh6 Nd2 195.Ng4 Bd4 196.Qb5 Rf4 197.Kh4 Be3 198.Qd3 Bd4 199.Kh5 Re4 200.Qa3 Rf4 201.Qd6 Re4 202.Nh6 Bf2 203.Kg6 Rc4 204.Qe5 Bb6 205.Qg3 Rc6+ 206.Kg7 Rc4 207.Nf7 Bc7 208.Qg1+ Kc2 209.Nh6 Be5+ 210.Kg8 Re4 211.Nf5 Bf4 212.Qh1 Be5 213.Qh3 Kd1 214.Kf8 Bf4 215.Qg4+ Ke1 216.Qg2 Be5 217.Qh1+ Ke2 218.Ke8 Bg3+ 219.Kd7 Bf2 220.Ne7 Rd4+ 221.Nd5 Kd3 222.Kc6 Rh4 223.Qg2 Rc4+ 224.Kb5 Be3 225.Qh1 Bc5 226.Qh7+ Ke2 227.Qh5+ Ke1 228.Kc6 Bd4+ 229.Kd6 Bf2 230.Kd7 Rd4 231.Qh1+ Ke2 232.Ke6 Rh4 233.Qg2 Rc4 234.Ke7 Nf3 235.Qh3 Re4+ 236.Kd8 Rd4 237.Qh5 Bg3 238.Qe8+ Be5 239.Qb5+ Kf2 240.Kc8 Re4 241.Kb7 Bd4 242.Qc6 Rg4 243.Ka6 Rg7 244.Nb4 Re7 245.Nd3+ Ke3 246.Qc1+ Ke4 247.Nb4 Re5 248.Qb1+ Ke3 249.Qc2 Rc5 250.Qd3+ Kf4 251.Qe2 Kg3 252.Qe7 Rh5 253.Nd3 Rh6+ 254.Ka5 Rh4 255.Qe6 Bc3+ 256.Ka6 Bd4 257.Qc6 Be3 258.Qe8 Bd4 259.Qb8+ Kg2 260.Qg8+ Kh3 261.Qg6 Rg4 262.Qc6 Kg3 263.Qc7+ Kh3 264.Nf4+ Kh4 265.Qd6 Kg3 266.Ng6+ Kf2 267.Qe6 Rg1 268.Nf4 Ra1+ 269.Kb7 Ra7+ 270.Kb8 Ra3 271.Qe2+ Kg3 272.Nd3 Rb3+ 273.Kc8 Rb6 274.Qe4 Rf6 275.Kd7 Bc3 276.Nc5 Bd4 277.Ne6 Be5 278.Ng5 Bb2 279.Qe3 Kg4 280.Ne4 Rf7+ 281.Kc6 Rf5 282.Nf2+ Kg3 283.Nd3 Be5 284.Kd7 Rf7+ 285.Ke8 Rf5 286.Qc5 Kg4 287.Nf2+ Kg5 288.Qd5 Kg6 289.Nd3 Bg7 290.Qe4 Kg5 291.Ke7 Bd4 292.Kd7 Rf6 293.Kc8 Rf8+ 294.Kb7 Rf7+ 295.Ka6 Rf6+ 296.Ka5 Bc3+ 297.Ka4 Ra6+ 298.Kb5 Ra5+ 299.Kb6 Rf5 300.Qe7+ Kg6 301.Qe8+ Kg5 302.Kb7 Bd4 303.Qe7+ Kh5 304.Qe4 Rf7+ 305.Ka6 Rf6+ 306.Kb5 Kg5 307.Nb4 Be5 308.Nd5 Rf5 309.Qe3+ Kh5 310.Ka6 Rf7 311.Qf2 Ng5 312.Qc2 Nf3 313.Qc8 Kg5 314.Qe6 Rf5 315.Kb7 Bd4 316.Qe7+ Bf6 317.Qe3+ Kh5 318.Qe4 Kg5 319.Nc7 Nd4 320.Qg2+ Kh5 321.Nd5 Nf3 322.Ne3 Rf4 323.Qh3+ Nh4 324.Qe6 Kg5 325.Qd5+ Kg6 326.Qd6 Kg5 327.Qc5+ Kg6 328.Qc7 Kg5 329.Nd5 Rf3 330.Qc1+ Kg4 331.Ne3+ Kg5 332.Nc4+ Rf4 333.Nb6 Kg4 334.Qd1+ Kg3 335.Nd5 Rf3 336.Qd2 Kg4 337.Ne3+ Kh5 338.Nc4 Bg5 339.Qd1 Bf4 340.Nb6 Bg3 341.Nd7 Kg5 342.Qd5+ Rf5 343.Qe4 Rf4 344.Qe7+ Kg4 345.Qe6+ Kf3 346.Nf6 Kg2 347.Qd5+ Kh2 348.Ne4 Nf5 349.Ng5 Nd6+ 350.Kb6 Bf2+ 351.Kc7 Bg3 352.Kd7 Nf5 353.Qd2+ Rf2 354.Qd1 Rf4 355.Qe2+ Rf2 356.Qh5+ Kg2 357.Kc6 Rc2+ 358.Kd5 Rd2+ 359.Kc4 Rf2 360.Qh3+ Kg1 361.Kb4 Rf1 362.Ka5 Rf4 363.Ka6 Ra4+ 364.Kb5 Rf4 365.Ka5 Rf2 366.Qh8 Kg2 367.Qc3 Rf4 368.Qd2+ Kf1 369.Qd5 Nd4 370.Kb6 Bf2 371.Kc7 Rh4 372.Qe5 Kg2 373.Ne4 Kf3 374.Nd2+ Kg2 375.Qd5+ Kh2 376.Kb7 Rh7+ 377.Ka6 Rh6+ 378.Ka5 Rh4 379.Qd6+ Kh3 380.Qd7+ Kg2 381.Qb7+ Kg3 382.Qg7+ Rg4 383.Nf1+ Kh3 384.Qd7 Kh4 385.Qh7+ Kg5 386.Qg7+ Kf4 387.Qc7+ Kg5 388.Nd2 Rf4 389.Qg7+ Kf5 390.Nc4 Nf3 391.Nd6+ Ke6 392.Ne8 Kf5 393.Ka6 Bd4 394.Nd6+ Ke6 395.Qg8+ Kf6 396.Qh7 Ke6 397.Ne4 Kd5 398.Qb7+ Ke6 399.Ng3 Be5 400.Qb3+ Kd6 401.Qb6+ Ke7 402.Ne4 Kf7 403.Qh6 Kg8 404.Qe6+ Kh8 405.Qe7 Rf5 406.Kb6 Bg7 407.Ng3 Rf6+ 408.Kb5 Nd4+ 409.Kc4 Rc6+ 410.Kd3 Rc3+ 411.Ke4 Rc6 412.Qe8+ Kh7 413.Kd3 Rd6 414.Qh5+ Kg8 415.Ne4 Rd8 416.Ke3 Bh6+ 417.Kf2 Rf8+ 418.Kg2 Kh7 419.Ng3 Ne6 420.Qh4 Ng7 421.Qe4+ Kg8 422.Qd5+ Kh7 423.Qd6 Rf7 424.Qd3+ Kg8 425.Qd5 Bc1 426.Kh3 Ba3 427.Kg4 Be7 428.Qc4 Kf8 429.Qc8+ Ne8 430.Nf5 Rf6 431.Qd7 Rf7 432.Qd3 Bf6 433.Qe3 Be7 434.Qh6+ Kg8 435.Qh1 Rh7 436.Qd5+ Kf8 437.Kf3 Nf6 438.Qe5 Ne8 439.Ke2 Bf6 440.Qd5 Rf7 441.Kd2 Bg5+ 442.Kc2 Rc7+ 443.Kb2 Bf6+ 444.Kb1 Rh7 445.Qf3 Ra7 446.Qb3 Rc7 447.Qb4+ Kf7 448.Qb6 Rd7 449.Qb3+ Kf8 450.Nh6 Rg7 451.Qa3+ Be7 452.Qf3+ Bf6 453.Ng4 Ke7 454.Kc2 Rg5 455.Qe3+ Kf7 456.Qb3+ Kf8 457.Qe6 Bg7 458.Ne3 Re5 459.Qb6 Bf6 460.Ng4 Rf5 461.Qe6 Rf4 462.Qc8 Bd4 463.Qd7 Bg7 464.Ne3 Rf2+ 465.Kb1 Rf7 466.Qc8 Rc7 467.Qa6 Rd7 468.Qa3+ Kf7 469.Qb3+ Kf8 470.Qb4+ Nd6 471.Qf4+ Kg8 472.Nd5 Nf7 473.Qc4 Ra7 474.Nf4 Rb7+ 475.Kc2 Rb2+ 476.Kd1 Rb6 477.Qc8+ Kh7 478.Qc7 Rd6+ 479.Ke2 Kg8 480.Qe7 Bf8 481.Qe8 Ng5 482.Qc8 Rf6 483.Qg4 Bh6 484.Nh5 Re6+ 485.Kf1 Re5 486.Qc8+ Bf8 487.Qc2 Re6 488.Qa2 Kh7 489.Qg2 Kh6 490.Qh1 Rb6 491.Nf4+ Kg7 492.Qh5 Nh7 493.Qg4+ Kf7 494.Qd7+ Be7 495.Qd5+ Kf8 496.Ne6+ Ke8 497.Qh5+ Kd7 498.Ng7 Nf6 499.Qf5+ Kc7 500.Qe5+ Kd7 501.Qd4+ Kc7 502.Qe3 Nd5 503.Qe5+ Kc6 504.Nf5 Rb7 505.Qe4 Kc5 506.Qc2+ Kb6 507.Qb3+ Kc6 508.Nd4+ Kc5 509.Qxb7 Kxd4 510.Kf2 Ke4 511.Qb1+ Kd4 512.Qg6 Bf6 513.Kf3 Be7 514.Qg1+ Kc4 515.Qg4+ Kc5 516.Ke2 Nf6 517.Qf5+ Kd4 518.Qf4+ Kd5 519.Kf3 Ke6 520.Qc4+ Kf5 521.Qa6 Nd7 522.Qd3+ Ke6 523.Qe3+ Kd6 524.Kf4 Nc5 525.Kf5 Bf8 526.Qf3 Nd7 527.Qc3 Ke7 528.Qd4 Ke8 529.Ke6 Nc5+ 530.Kd5 Nd7 531.Kc6 Nb8+ 532.Kb6 Nd7+ 533.Kc7 Nc5 534.Qc4 Be7 535.Qg8+ Bf8 536.Kc6 Na6 537.Qe6+ Be7 538.Qc8+ Kf7 539.Qxa6 Ke6 540.Qd3 Bg5 541.Qe4+ Kf6 542.Kd6 Bd2 543.Qe5+ Kg6 544.Ke6 Bg5 545.Qf5+ Kh5 546.Qf3+ Kh6 547.Qf7 Bh4 548.Kf5 Bg5 549.Qg6#

```
> 4 votes

---
Tags: engines, records, tablebases
---


# Question
Title: What are some checkmates with very few moves from the starting position?
I would like to learn about a few checkmates using very few moves. I know one where you develop the knight and march it directly towards the King. Does anyone know the name of this mate and suggest others?

# Answer
> 47 votes
There are probably as many quick mates as there have been first time players (since we all get caught in these at the start!) but here are a few common ones:

## Fool's Mate

This is the shortest possible checkmate in a mere two moves:

1.f4 e5 2. g4 Qh4#

```
[FEN ""]

1. f4 e5 2. g4 Qh4# 0-1

```

White can also play f3 instead of f4 or move the g pawn before the f pawn.

## Scholar's Mate

This mating pattern is also sometimes referred to as "Fool's Mate" and there are two main patterns:

1.e4 e5 2. Bc4 (2. Qh5 Nc6 3. Bc4 Nf6 4. Qxf7#) Nc6 3. Qf3 Bc5 4. Qxf7#

```
[FEN ""]

1. e4 e5 2. Bc4 (2. Qh5 Nc6 3. Bc4 Nf6 4. Qxf7#) Nc6 3. Qf3 Bc5 4. Qxf7# 1-0

```

The key is that f7 is insufficiently defended and mate is delivered there.

## Légal's Mate

Légal's Mate (also spelled as Légall's Mate) is probably the mate referenced in the question:

1.e4 e5 2.Nf3 Nc6 3.Bc4 d6 4.Nc3 Bg4 5.h3 Bh5? 6.Nxe5! Bxd1?? 7.Bxf7+ Ke7 8.Nd5#

```
[FEN ""]

1.e4 e5 2.Nf3 Nc6 3.Bc4 d6 4.Nc3 Bg4
5.h3 Bh5? 6.Nxe5! Bxd1?? 7.Bxf7+ Ke7 8.Nd5# 1-0

```

# Answer
> 33 votes
For a short mating possibility in a very standard mainline opening, one can look to the Smyslov-Karpov variation in the Caro-Kann Defense:

```
[FEN ""]
[Result "1-0"]
1.e4 c6 2.d4 d5 3.Nc3 dxe4 4.Nxe4 Nd7 5.Qe2 Ngf6?? 6.Nd6#

```

The most popular continuations are `5. Nf3`, `5. Bc4` and `5. Ng5` (an aggressive try which Kasparov assayed a number of times against Karpov). The sneaky try `5. Qe2` just sets up a pin against Black's e-pawn, making the intended followup `5... Ngf6??` unplayable.

There are a mere 271 games in my database (out of several million) in which this 5. Qe2 appears, but one finds a few GMs giving it a go: Ivan Radulov, Oleg Nikolenko, Joe Gallagher (against as strong an opponent as IM Tibor Karolyi), even some guy named Alekhine (though, admittedly, only in a consultation game against a team of four amateurs). A 2300 player also tried it out against Yasser Seirawan on the black side; Seirawan didn't fall into the trap of course, but the 2300 did manage to get a draw out of the game.

If you're still reading, you're probably curious: out of the 271 games I have on record, in only 34 of them did black fall into the trap with `5... Ngf6`. Alekhine's amateur foes were among the victims, and the highest rated victim was in a game Hans Speck (2140) - Nikolaus Mertens (2165) from the 1997 Liechtenstein Open. **Most interestingly**, on two of those 34 occasions, the white player failed to reply with `6. Nd6#`. One was a player rated 1873 who went on to lose to his 2202 opponent; the other was rated 2264(!) and managed to win anyway against a 2113 on the black side.

# Answer
> 15 votes
The Scholar's and Fool's mates that others have cited are the shortest. They rely on two different but highly important principles chess players should remember. Scholar's mate relies on the opponent's insufficiently protected f2 (or ...f7) point, while Fool's mate relies on a weakening of the diagonal from h5 (or ...h4) to the opponent's king.

While you can actively try for Scholar's mate (and many weak amateurs fall for it), Fool's mate pretty much relies on very poor play by the opponent -- advancing the f and g pawns such that the critical diagonal is fatally weakened. A variant of Fool's mate is more likely to occur that involves several more moves and induces the opponent to make the required weakening moves. Consider the following sequence; White's fourth move is a fatal mistake leading to the loss of his queen or getting mated along the ...h4-e1 diagonal.

```
[FEN ""]
1. d4 Nf6 2. Nd2 e5 3. dxe5 Ng4 4. h3?? Ne3 5. fxe3 Qh4+ 6. g3 Qxg3#

```

An excellent old book that should probably be a new player's second or third book is "The Art of Checkmate", despite being so old it still uses descriptive notation:

http://www.amazon.com/The-Art-Checkmate-Dover-Chess/dp/0486201066

# Answer
> 14 votes
A mate in 2½ move, derived from Wayward Queen Attack, occurs if black moves Ke7 as a panic attempt to "protect" the e5 pawn with the king, which may occur if young players move too quickly:

```
[FEN ""]

1. e4 e5
2. Qh5 Ke7
3. Qe5#

```

# Answer
> 12 votes
```
[FEN "nbqnbrkr/pppppppp/8/8/8/8/PPPPPPPP/NBQNBRKR w KQkq - 0 1"]
[StartPly "3"]

1. d3 {Pyt Honisten eröffnet mit seinem Lieblingsbauern} g5 {Retho Riker antwortet mit seiner Standard-Antwort} 2. Qxg5# {Pyt Honisten ging zum nächsten Brett, während sich Retho Riker tränenreich vom Schach verabschiedete.}

```

With Chess960, also known as Fisher Random Chess, you can achieve it, too.

# Answer
> 12 votes
The Blackburne-Shilling Gambit could result in a quick loss for White if he plays some fairly plausible moves:

1.e4 e5 2.Nf3 Nc6 3.Bc4 {Italian opening} Nd4 4.Nxe5 {Free pawn!} Qg5 5.Nxf7 {Forking the queen and rook.} Qxg2 6.Rf1 {Preventing Qxh1} Qxe4+ 7.Be2 {Qe2 Nxe2 drops the queen} Nf3#

```
[FEN ""]
1.e4 e5 2.Nf3 Nc6 3.Bc4 {Italian opening} Nd4 4.Nxe5 {Free pawn!} Qg5 5.Nxf7 {Forking the queen and rook.} Qxg2 6.Rf1 {Preventing Qxh1} Qxe4+ 7.Be2 {Qe2 Nxe2 drops the queen} Nf3#  0-1

```

# Answer
> 8 votes
There's a 2-move checkmate, termed fool's mate:

> 1. f3 e5 2. g4 Qh4#

Fool's mate on Wikipedia

# Answer
> 7 votes
```
[FEN ""]

1. d4 Nf6 2. c4 c5 3. d5 b5 4. cxb5 a6 5. Nc3 axb5 6. e4 b4 7. Nb5 Nxe4 8. Qe2 Nf6 9. Nd6#

```

# Answer
> 7 votes
To add to the Fool's Mate idea, this game left enough of an impression on me to remember it.

```
[FEN ""]
1. d4 f5 2. Bg5 {An enterprising line, threatening to weaken Black's pawn structure after the natural Nf6.} h6 3. Bh4 g5!? {This seems to trap the bishop, but the holes around the Black king are very dangerous. It is objectively OK, but only if Black does not play to win material.} 4. Bg3 f4? {This move is a definite mistake.} 5. e3! {Now fxg3 leads to Qh5#, and White threatens to rescue his bishop with exf4} h5 {Renewing the threat, now 6. exf4 h4 and the bishop is still trapped} 6. Bd3 {Objectively this move isn't the best, but it threatens Bg6#} Rh6?? 7. Qxh5+! Rxh5 8. Bg6#

```

# Answer
> 4 votes
The Kieninger Trap in the Budapest gambit has trapped numerous amateurs but even some masters over the years. It involves a similar mating pattern to those found in some of the other answers. There are only so many ways to blunder a king early in the game.

1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nbd2 Qe7 7.a3 Ngxe5 8.axb4 Nd3#

```
[FEN ""]
1.d4 Nf6
2.c4 e5
3.dxe5 Ng4
4.Bf4 Nc6
5.Nf3 Bb4+
6.Nbd2 Qe7
7.a3 Ngxe5
8.axb4 Nd3#

```

# Answer
> 3 votes
Here’s a simple example which I always like.

```
[FEN ""]
1. d4 e5 2. Bg5 Qxg5 3. Qc1 Qxc1#

```

# Answer
> 3 votes
Against the Bird Opening (1.f4), black can play the From Gambit which threatens a kind of fool's mate:

```
[FEN ""]

1.f4 e5 2.fxe5 d6 3.exd6 Bxd6 4.Nc3? Qh4+ 5.g3 Qxg3+ 6.hxg3 Bxg3#

```

Instead of 4.Nc3, which is just an example move, 4.d4 and 4.g3 are common.

# Answer
> 3 votes
Légal's mate, which Andrew mentioned, can also occur in the Italian Opening, with a move order which is perhaps more credible:

1.e4 e5 2. Nf3 Nc6 3. Bc4 d6 4. Nc3 Bg4? 5. h3 Bh5? 6. Nxe5! Bxd1? 7. Bxf7+! Ke7 8. Nd5#.

Black has a similar trap in the Petrov:

1.e4 e5 2. Nf3 Nf6 3. Nxe5 Nc6? 4. Nxc6 dxc6 5. d3 Bc5 6. Bg5? Nxe4! 7. Bxd8? Bxf2+ 8. Ke2 Bg4#.

John Coleman mentioned the Kieninger Trap, a Black trap in in the Budapest gambit. White has two traps in the Caro-Kann that are similar to this:

1.e4 c6 2. d4 d5 3. Nc3 dxe4 4. Nxe4 Nd7 {Nf6 is better} 5. Qe2?! Ngf6? 5. Nd6#

This also works after 2. Nc3 d5 3. Nf3.

---
Tags: checkmate, patterns
---


# Question
Title: An Interesting Idea: Pinned Pieces Stalemate
I had an idea for a type of stalemate: One side is stalemated with 8 pins in a legal position with as many pieces as possible, with all of the stalemating side’s units being “necessary.”

”Necessary” is defined as either pinning a piece, blocking a piece, or covering a king’s flight square. The king must be involved of course.

As a bonus optional question, what is the maximum number of units in a legal position with 4 “natural” pins, which means no promoted pinning pieces?

# Answer
> 3 votes
```
 [FEN "b3r3/1R1p1p1q/1p1P1P1b/1Pk1BR2/1rN1K1Nq/p7/P1P1B1P1/1qn1q1nq w - - 0 1"]

```

Here is an (ugly) suggestion wth **29 units**.

White is stalemated with 8 pins; removing any Black unit would break the stalemate. Black has promoted all of their four missing pawns (all into queens).

The three captures (white queen and 2 white pawns) ensure that this position is reachable. The three missing White pieces ensure that the position is legal and that Black could have promoted all four of their missing pawns.

The Black g-pawn captured the White h-pawn to produce doubled pawns that both promoted. The Black c-pawn captured the White queen to bypass the White pawn structure and promote. Finally, the White e-pawn was captured and then the Black e-pawn marched down and promoted.

This is optimal because 4 pawns must be promoted to create 8 pins, with requires a minimum of 3 units, thus leaving 29 left for the final position.

# Answer
> 6 votes
**Bonus question** : 4 pins stalemate without promoted piece.

Here is a maximal solution with all **32 units** :

White's Rc2, Bd5, Nf2 and Ng6 are pinned. The king has no move and all the other white pieces are stuck.

Removing any black piece, or moving the black King away, would break the stalemate.

Removing the bPg4 would be particularly unfortunate because White, in spite of having almost all their army stuck, would deliver mate with their only legal move, g3-g4#.

# Answer
> 2 votes
Regarding the bonus question, for 4 “natural” pins, here is a position with **30 units.**

```
[Title "me, chess.stackexchange.com 8/9/2019"]
[FEN "4r3/1b1pB3/1nRP1pkb/pPp4p/PrB1K1pP/1P2PpP1/2R2P2/Nqn4N w - - 0 1"]

```

---
Tags: problems, stalemate, pins
---


# Question
Title: Evaluation function in a bitboard based chess engine
How do you go about writing an evaluation function for a bitboard bases chess engine? I want to start of simple and only evaluate based on piece value, and where the pieces stand. For example a knight on c3 should give more points than a knight on a3.

I can start with making an array of size 64 for each piece with weights. For example I can store the value 0.1 in the square c3 and -0.1 in the square a3 for the knights. Then I could loop over the 64 squares and check if any of the 12 piece types are in this square and add (or subtract) it from the total evaluation. However it seems like this is very slow.

If I were only counting the piece values then I could use a pop count on each bitboard to get the value, but I don't see how I can implement the square weights this way.

Is there a smarter way to think about this?

# Answer
Given there is a maximum of 16 pieces on the chessboard you could loop on the pieces instead of the 64 squares. In this way, the less pieces on the board the faster. Each piece contains the index of the square, you then only have to pick the value of the corresponding weight to have your score. As each piece could have their own array of weight you can even pre compute the values on the weight adding the piece value and the position. If the performances really matter, use a profiler to know where is the bottleneck. You might end up using integers instead of floats, pointers instead of indexes, masks for operations and other smart operators to run operations in the same time.
> 1 votes

---
Tags: engines, programming, bitboard
---


# Question
Title: Why was move-sealing introduced in adjournment?
As some background, in the pre-engine era time-controls were often slower and chess players could adjourn their games, taking a break till the next day and resuming from the same position.

In all turn-based boardgames where this is or was an option, as far as I can see (chess, Go, Shogi, ...), adjournment was accompanied by 'move-sealing': one player writes down the move they will make, the other player does not see it, and the next day play begins with this move.

This was obviously a measure to avoid the inequity of discontinuing the game in a position where one player knows the exact gamestate while preparing their move. (For example, if I play my move openly rather than sealing it, and the game then adjourns, my opponent has an advantage because they can prepare a response to that exact move.) However, it is not obvious to me that this fully avoids inequity: there is a clear advantage for the sealing player, as they will know the starting gamestate the next day and the opponent will not.

What is the justification for this second advantage being less than the first?

# Answer
> However, it is not obvious to me that this avoids inequity: there is a clear advantage for the sealing player, as they will know the starting gamestate the next day and the opponent will not.

But the opponent has the move!

So the sealing player knows their own move, but doesn't know what the opponent will reply to it. And the opponent knows the position *before* the sealed move, but doesn't know what move was sealed.

It's probably not *completely* equal, but I don't see a way to get closer than this.
> 35 votes

# Answer
Sealing can provide an advantage to the sealing player - but it's not *that* clear. The point is that after you seal a move, it is opponent's turn, so neither player knows with certainty what the position will be when it's their turn to move. If both players have many many possible, reasonable moves then both players have to prepare for all of them. However, if the sealed move forces a specific response then the sealing player has the advantage.

You can see some discussion on this from the two videos by Nakamura and Carlsen on a game from the *Queen's Gambit*. At 1:30 in Carlsen's video, he specifically says Borgov makes a mistake by adjourning the game when he only has one decent move, which obviously makes it easy for Harmon to prepare. Nakamura analyzes the position as well around 3:30 in his video. To quote, "Borgov should have played 36...Qg6, and then after 37. Ne6 he should adjourn." So because Borgov chose to adjourn at a bad time, his opponent gains the advantage.

There's one more point: as you can see from the Wikipedia article on adjournment, both players can choose to adjourn the game at any moment after the allotted time has passed. However, choosing to adjourn comes with the drawback of forfeiting all your remaining time. Your opponent keeps their time, which can be an advantage if complications arise after resumption.
> 14 votes

# Answer
I'm not sure about the exact quote or source, but it's something like

> Chess is won by the player who makes the second-to-last mistake.

The sealed move, the last one of the day, perhaps made a few minutes after an intense time-trouble battle, may be the last mistake. The opponent has a lot of time to 'guess' the sealed move, and could concentrate their analysis not only on the best move in the position, but also on potential mistakes which could quickly be refuted.

This is likely not enough of an advantage to compensate for knowing the starting position next day, but at least it's better than the alternative (with both players knowing it).
> 8 votes

# Answer
> However, it is not obvious to me that this avoids inequity: there is a clear advantage for the sealing player, as they will know the starting gamestate the next day and the opponent will not.

Not necessarily. For quite a few board states, there's only one non-blunder move, and sometimes only one legal move. And there's pretty much never more than a dozen feasible moves (and I could probably go a lot smaller than "dozen" and still have that statement be correct, I'm just being cautious).

Suppose the players' time averages to 10 min per move, and the board state at adjournment is such that there are 10 moves that aren't obviously stupid (for both of these numbers, I picked numbers that I think are on the upper end). If the non-adjourning player spends 20 min on each of those moves, that's 200 min total. And then, no matter what the sealed move ends up being, the non-adjourning player has spent double the normal time on analysis, with no time being charged to their clock. And in the days of adjournment, players were often allowed to have a second, or even a team, that they could consult with. So if there's two plausible moves, the player can assume that one of them will be made, and spend all night deciding on a response, and the second could assume that the other would be moved, and spend all night deciding on a response to that.

Now, of course, the adjourning player can do something similar: they can take all the possible responses, and do an analysis for each of them. So it comes down to which player's move is less predictable; if a player has more viable moves, then the other player's analysis has to be split between more moves, and so the amount of time per move is smaller. On average, each player is equally likely to be advantaged by the adjournment. Adjourning at the right time can be a large advantage, but the advantage comes from picking a point where the complexity tree is most in your favor, not in knowing what the next half-move is. Basically, you want to stop at a point where you're the next player to add uncertainty to the game.

> What is the justification for this second advantage being less than the first?

In any board state, there's a finite number of legal moves. There no rule saying that the non-sealing player can't write down every legal move, and their response to it, before leaving the playing area. Now *they* know exactly what the board state will be in the morning! Committing to a move is a steep price to pay for knowing what the board state is.

With sealed moves, one player has the advantage of knowing the board state, and the other has the advantage of their next move being free. Without sealed moves, one player would have both advantages. It's not a case, as you put it, of choosing between giving one sort of advantage, or giving another sort of advantage. It's a case of choosing between giving *two* advantages, or giving only one.

Suppose you're White, it's Black's turn, and you have a choice between:

(A) Black makes their move secretly, it's sealed, and then there is an adjournment.

(B) Black makes their move publicly, you make a move publicly, and then there is an adjournment.

Which would you prefer? In both cases, Black knows the board state, but Black's advantage in (A) is nowhere near Black's advantage in (B). I, and I expect the vast majority of chess players, would much prefer (A).
> 5 votes

# Answer
It could occasionally be advantageous, and even strongly so, either way. I can recall being in a pawn-up Rook endgame well ahead on time, but unsure of the correct plan. I waited without moving until I could seal a noncommittal move. Alternatively a situation could have arise where I might have been obliged to seal a committal move. I do not think there was much of a systematic advantage either way

Incidentally, the sealed move itself was almost always the first move after the time control, and so was never made in time pressure unless for some exceptional reason. Arbiters accepted to remain in the playing hall as long as they needed to while the player made a decision
> 4 votes

# Answer
It's not the idea of advantage to the sealing player 'cause he knows the move that will resume play. That's not an advantage to him anyway, and there's a far, far more important issue that arises if he doesn't seal a move.

If he does not seal a move, and it is, oh, 17 hours until play resumes, he gains 17 hours... 1020 minutes of time to consider his next move and be ready to play it. So, if each player ended up using two hours of on the board time, the sealing player had 19 hours to consider his moves while the other player had 2 hours to consider his moves.

To kill off the niggling quibble here and to point out why it was never much of a "knowing the next move advantage" consider the ways you can look at it. I am referring only to time used to consider real, my move is next, what shall I play, oh, and I know everything there is to know about the opponent's moves since they've all been made, kinds of moves. Yeah, sure, I can think "on my opponent's time" but he could play lots of moves and if he's thinking about things while I think too, then clearly at least two of them intrigue him. What are those two? Maybe that's easy to predict, maybe it's not. I have quandaries and some amount, maybe a lot of it, of the time I think "on my opponent's time" is pointless as the opponent makes some other move altogether, or since he can only make one move, the time I spent considering his other options was rendered "wasted."

If I seal a move, then BOTH of us analyze from that point with one opponent's move "in between" the position now and our next move. In his case, my unknown sealed move is in between now and his next move. He must waste some time pondering paths forward that won't happen due to my sealing a move that makes other paths happen. But... I may know the next move that will happen, but the move he must make, the one I just mentioned, is in between the move I sealed and whatever next move he makes. Both of us have plenty of time to think about everything but both of us have one opponent's move in between now and our next move and that opponent's move could be many things.

Sealing is and was simply a method to maintain that fact and apply fairness to all.

Remember, if I don't seal a move, there is no opponent's move in between now and my next move. EVERYTHING I spend time on is then worthwhile, nothing wasted, for me. A huge advantage over my opponent.

I'd also point out that after whatever time control after which adjournment was allowed, EITHER player could choose to seal his move. Not just, say, White. That had a minimum of two important effects.

First, why would either player seal a move in a situation in which his next move was dead obvious (due, for example, to hanging a queen if he doesn't seal a particular move... might as well be clear about how advantage could be had there)? Do so, and you might are adjourning the game in a situation in which the opponent is essentially thinking "OK, if he doesn't make "the move" I take the queen and win. That was four seconds. So, let's spend the other 16:59:56 doing real analysis assuming he makes "the move." Yay, this is soooo sweet!" So almost by definition, a sealed move will be one in which the position has some amount of complexity.

Second, a player could actually choose to aim for "very complicated" so as to minimize his opponent's benefit from the extra thinking time. The opponent would have to consider all the reasonable moves while he knows the move chosen and might enter his analysis looking at a much simpler future, thereby gaining an advantage. I'd say two mitigating things though about that advantage. One is that most complex situations seem to arise over a few moves, not instantly after a single move, and as a practical issue, why would you want to give him the, say, 17 hours, to think about the "sitch" instead of making him burn clock time? So moderately complex situations, not clock burners per se, but not 2) ... Kc6 either, would seem the target and most folks playing at a level in which sealing occurs ought to be able to handle things without the opponent gaining large advantage. The other is that either player can adjourn, so your opponent sees you're aiming at something and adjourns a move before you intended to. Now YOU have any disadvantage that arises.

So basically, it is/was just meant to make adjournment not the source of possibly incredible advantage to one player. Everything else is details and small plus/minus effects. EACH player is in the position of analyzing all he cares to, but always while not knowing his opponent's next move. Not just the non-sealer. Just keeping the playing field as level as the situation can permit.
> 1 votes

---
Tags: tournament
---


title: Multiple day online swiss tournament

text:
# Question
Title: Multiple day online swiss tournament
I want to organize a 6 round swiss tournament for 100+ players with 3 rounds/day.
I know there are websites which allow us to organize swiss tournaments
ex :- chess.com,lichess.org.
I want to know if there are websites which allow the swiss tournament to go on for many days.

# Answer
> 3 votes
Yes, Lichess Swiss tournaments allow a tournament to last several days. But to achieve your goal of three rounds per day you will need to set the value of *Interval between rounds* to "Manually schedule each round". In that case, rounds will not start automatically like when you set the interval to "1 day(s)", for example.

Please notice that Lichess Swiss tournaments can only be created by team leaders, and can only be played by team members. The reason they give is that this type of tournament demand punctuality, dedication and patience from players, and these conditions are more likely to be met within a team than in global tournaments.

Also note that an odd number of rounds allows optimal color balance.

---
Tags: tournament, online-chess, lichess, websites, chess.com
---


# Question
Title: Why is 3...g6 the main line of the Pirc Defense?
I admit that I've only started taking chess seriously in the past few months, but I'm having some trouble wrapping my head around this bit of theory. To be crystal clear, when I refer to the Pirc Defense, I'm referring to the following (or some transposition thereof):

```
[FEN ""]
1.e4 d6 2.d4 Nf6 3.Nc3 g6

```

I know I understand Black playing Nf6, and I can understand the logic *somewhat* of d6 since it opens up Black's queenside bishop while preventing e5 from White, but I can't understand the benefit of g6. I know that the idea is that it allows Black to fianchetto kingside at some point, but I can't comprehend why that would be desirable here. White's d pawn blocks access to the knight on c3, meaning it's not pinned, and black's only developed knight blocks the move anyway. Is the appeal just that it threatens Bb4+ at some point in time, or is there something more elegant that I'm missing?

# Answer
> 5 votes
It seems to me that it's the best way to quickly develop the bishop and castle. The pawn on d6 prevents the bishop from developing immediately to (say) b4. Developing to g7 puts the bishop on a long diagonal, which is a great place for a bishop to be. Even if it doesn't make immediate threats, it will likely have a lot of mobility as soon as the knight moves, and may end up threatening a1 or b2 later on. Moreover, since white has a large pawn center in this opening, castling early should be a priority, and the fastest way to do that is to develop the kingside bishop.

---
Tags: theory, fianchetto, pirc-defense
---


title: Woodpecker method on chess sites

text:
# Question
Title: Woodpecker method on chess sites
Is there any chess site that allows you to train tactics by repeating some number of problems over and over again?

# Answer
I think Chessable is pretty close to what you want. There are courses made usually by masters, some are free, some with a price. But you can create your own course and study it too. After you study something, you need to repeat the same problem after some time.

The repetition type has 3 choices:

* **Chessable Spaced Repetition:** It is a special repetition type where the time between repeats are getting longer and longer (like 1 day - 3 days - 1 week ...).
* **Cyclical:** Repeat times are constant (like 1 day - 1 day - 1 day ...).
* **Custom:** This needs Pro Chessable account, you can set the times whichever you like.

For cyclical, there is a note like this from Chessable:

> If you are following the Woodpecker cycle, after you complete the first cycle and the exercises start popping up for review, you can now go and set a shorter cycle, which you can do, by changing the cycle end date again, to say, two weeks from the date at the end of your first cycle.
> 3 votes

---
Tags: tactics
---


# Question
Title: What checkmating move takes the most moves to set up?
An extension of this question.

What checkmating move requires the greatest number of moves to be played in a game?

A move is distinguished by:

* what colour is moving \[unlike the previous question\]
* what type of piece is being moved
* from where
* to where
* whether it is a capture
* what piece it is being promoted to, if any

(And notably, not which piece \[if there is one\] is being captured, nor if it's en passant.)

(In the case of a castling move, "the piece" is the king.)

For instance, "White Qd1h5#" takes a minimum 5 half-moves (can be played on White's 3rd move). "Black Qf6xf2#" takes a minimum 8 half-moves (can be played on Black's 4th move).

# Answer
> 5 votes
Nice question!

Can anyone reach ...Ka2xb3# sooner than Black's 15th (30 plies)?

1.b4 a5 2. bxa5 Rxa5 3. d3 Rxa2 4. Kd2 Rxa1 5. Ke3 e6 6. Nd2 Ke7 7. Bb2 Kd6 8. Bf6 Kc5 9. Ndf3 Kb4 10. Kd4 Ka3 11. Kc4 Ka2 12. Kb5 d6 13. Ka5 Qe7 14. c3 Bd7 15. Qb3+ Kxb3#

```
[FEN ""]
1.b4 a5 2. bxa5 Rxa5 3. d3 Rxa2 4. Kd2 Rxa1 5. Ke3 e6 6. Nd2 Ke7 7. Bb2 Kd6 8. Bf6  Kc5 9. Ndf3 Kb4 10. Kd4 Ka3 11. Kc4 Ka2 12. Kb5 d6 13. Ka5 Qe7 14. c3 Bd7 15. Qb3+ Kxb3#

```

\[ My first thought was

...a6-a5#

This can't be a discovered check, and must therefore be direct, entailing wKb4. This in turn entails 3 wK moves and one wP move to let wK out. Then 8 squares in wK's field (which are currently all empty and none guarded by Black) must each be either occupied by White or guarded by Black. This can be achieved on the 12th ply e.g.

1.d3 d6 2.Kd2 Be6 3 Kc3 a6 4.Kb4 Qd6 5.a3 b6 6.c3 a5#

```
[FEN ""]
1.d3 d6 2.Kd2 Be6 3 Kc3 a6 4.Kb4 Qd6 5.a3 b6 6.c3 a5#

```

\]

# Answer
> 3 votes
Some tentative thoughts:

## Preliminaries

A checkmating move is either a discovered check, or a direct check. (Possibly both, but likely not relevant). Any proposed checkmate move must consider each possible form.

* B,N,R,P: can direct check or discovered check (unless starting in a corner, or moving along an edge in the case of R).
* K: can discovered check
* Q: can direct check

AFAIK, any possible move is a candidate for a checkmate except:

* a K move along the side of the board
* a B move from one corner to the other

There aren't many moves that really force the opposing king to be in a particular spot. Pawn moves that finish on the edge of the board (eg, a3-a4# or b3xa4#) are the only exceptions (in this case, the king must be at b5). Many moves (say Bb2c3#) are more easily reached with a discovered check (say, a rook along the b file or 2nd rank).

Assuming for the moment that White is mating, the number of half moves required can be described as:

* White: (moving mating piece into position) + (getting other pieces out of the way of mating piece) + (capturing pieces to help king) + (moving pieces into position to attack king's escape squares) + 1 (mating move)
* Black: (getting king into position) + (moves capturing pieces to help mating piece) + (moving pieces into king's escape squares)

## Possible goals

It's not immediately obvious which of these mutually incompatible goals is most important:

* forcing the king to move to an inconvenient square far away
* forcing the mating piece to do the same
* choosing a mating location that requires a lot of pieces to enclose (such as the centre of the board, rather than on an edge, or next to where other pieces start)

A good way of forcing the black king to move a long way is for the mating move to be a king move from rank 1 to 2 or similar - so the discovered attack is along a rank.

## Unpromising avenues of exploration

* Pawn promotions: it only takes 5 moves, and the goal is close to where the mated king starts, where it is already fairly trapped by the edge of the board and its own pieces.
* Queen moves: hard to see how this would ever take longer than a rook or bishop.

## Some possible candidate moves (with White mating)

### Kb2xb1

I now realise that Black's king could be mated by a bishop on a1, like this:

> 1. e4 Nf6 2. Qf3 g6 3. Na3 Bh6 4. b3 Kf8 5. Rb1 Nxe4 6. c4 Nxd2 7. Kd1 Nxb1 8. Kc2 f5 9. Bb2 e5 10. Ba1 e4 11. Kb2 Kg7 12. Qxf5 Qg8 13. Kxb1#

```
[FEN ""]
1. e4 Nf6 2. Qf3 g6 3. Na3 Bh6 4. b3 Kf8 5. Rb1 Nxe4 6. c4 Nxd2 7. Kd1 Nxb1 8. Kc2 f5 9. Bb2 e5 10. Ba1 e4 11. Kb2 Kg7 12. Qxf5 Qg8 13. Kxb1#

```

That's 13 moves, and definitely not optimal.

### Kb1xb2

By having the king start on the first rank, we ensure the only discovered check is a rook along the same rank, so black's king must cover the whole board.

Along these lines:

```
rnbq2nr/pppppp1p/8/8/2P1P3/3P4/PbQ3PP/RK2kBNR w KQ - 0 1

```

This can be achieved in 13 moves (25 half-moves), and likely fewer:

```
[FEN ""]
1. d3 g6 2. c4 Bh6 3. f4 f6 (3... f5 4. Kd2 Bxf4+ 5. Kc2 Kf7 6. Na3 Kf6 7. Kb1 Kg5 8. Qc2 Bxc1 9. c5 Kf4 10. c6 Ke3 11. cxb7 Kf2 12. e4+ Ke1 13. h4 Bxb2 14. Kxb2#) 4. f5 Kf7 5. fxg6+ Kxg6 6. Na3 Bxc1 7. Qb3 (7. Qc2 Bxb2) 7... Bxb2 8. Kd2 Kg5 9. Kc2 Kf4 10. Kb1 Ke3 11. Qc2 Kf2 12. e4+ Ke1 13. Kxb2#

```

---
Tags: problems, puzzles
---


# Question
Title: What is the longest tablebase win that includes draw rules?
It has been asked the longest mate that includes draw rules is, and it is known what the longest tablebase mate is. However, what is the longest tablebase mate, i.e. 7 pieces or less, that accounts for the 50-move rule?

# Answer
> 5 votes
Unfortunately looking for the longest mates on Kyrill Kryukov and checking with Syzygy won't give you the answer. The mate lengths ignoring the 50 move rule don't correspond with the mate lengths when the rule is in force. For example this position with a ply count of 0 under the 50 move rule is mate in 112, but ignoring the 50 move rule it's mate in 91.

```
[Title "White to move, ply count 0"]
[FEN "6k1/p7/8/8/7N/7K/2N5/8 w - - 0 1"]

```

Indeed the longest mate in this endgame with the 50 move rule in effect is 128 moves from the following position, which is mate in only 85 if the rule is ignored. But that is with a ply count of 4 or 5. (The longest mate in this endgame without the "draw" rules is only 115).

```
[Title "Black to move, ply count 4 or 5 "]
[FEN "8/8/5N2/p7/8/k1K5/8/1N6 b - - 0 1"]
[startflipped ""]

```

In fact none of the currently available tablebases will give you an answer. What you need are DTM50 tablebases which I believe are currently in progress.

See here for a full explanation: http://galen.metapath.org/egtb50/

In general if the ply count exceeds 3 the mates could get even longer owing to the necessity of avoiding triple repetitions (though that wouldn't apply in the above case). So you may not have an answer even with the DTM50 tablebases because the DTM50 tablebases wouldn't take this into account. (They would play perfectly accurately from ply count 0 positions, i.e. if used by an engine from the time the endgame appeared.)

---
Tags: endgame, checkmate, tablebases, records, 50-move-rule
---


# Question
Title: What is the shortest sequence of moves to move all of White's pieces up to at least the third rank?
What is the shortest sequence of moves to move all of White's pieces to the third rank or beyond? Assume in this situation that Black is cooperating in trying to achieve this goal, and as such is simply shuffling their knight back and forth to not impede White's progress. The shortest I've found is the following:

```
[FEN ""]
1.e4 Nf6 2. d4 Ng8 3. Ba6 Nf6 4. Bh6 Ng8 5. Qh5 Nf6 6. Nf3 Ng8 7. Nc3 Nf6 8. Rd1 Ng8 9. Rd3 Nf6 10. Kd2 Ng8 11. Re1 Nf6 12. Ree3

```

Is there a quicker way to do this? For a more challenging variant of the problem - what's the shortest series of moves to get all of White's pieces *and* pawns to the third rank or beyond?

# Answer
> 6 votes
(As @JamesMartin suggested) 11 moves is the quickest possible way. There are 7 pieces to move, 2 of them are bishops which you need to open the way, 2 of them are rooks which you also need to open the way. 7 + 2 + 2 = 11.

```
[FEN "rnbqkbnr/pppppppp/8/8/P1BPPBQP/R1N2N1R/1PP2PP1/4K3 b kq - 14 11"]
1. a4 Nf6 2. d4 Ng8 3. e4 Nf6 4. h4 Ng8 5. Rh3 Nf6 6. Raa3 Ng8 7. Bc4 Nf6 8. Bf4 Ng8 9. Qg4 Nf6 10. Nf3 Ng8 11. Nc3

```

**Bonus:** The quickest way for all pieces to move to third rank or beyond. 8 pawns, 8 pieces, king needs to move 1 more to third rank, 8 + 8 + 1 = 17. (15 without king)

```
[FEN "rnbqkbnr/pppppppp/8/8/PPPPPPPP/RQNBBNKR/8/8 b kq - 18 17"]
1. a4 Nf6 2. b4 Ng8 3. c4 Nf6 4. d4 Ng8 5. e4 Nf6 6. f4 Ng8 7. g4 Nf6 8. h4 Ng8 9. Rh3 Nf6 10. Nf3 Ng8 11. Bd3 Nf6 12. Ra3 Ng8 13. Be3 Nf6 14. Nc3 Ng8 15. Qb3 Nf6 16. Kf2 Ng8 17. Kg3

```

---
Tags: problems
---


# Question
Title: In this game, should white sacrifice their bishop to expose black's king?
I (black) reached this position in a game and realised that black's king would be totally exposed if white's bishop decided to take the pawn (1. Bxh6 gxh6).

Is the smart move here for white to sacrifice their bishop and to expose the opponent's king? Or since you can't see that far into the future, maybe it's just worth keeping your piece. What do you think?

```
[FEN "r2q1rk1/pp2b1p1/3p1nbp/1Np1p1B1/1nP1P3/6PN/PP2QPBP/R4RK1 w Qq - 0 1"]

1.Bxh6 gxh6

```

# Answer
The sacrifice makes very little sense here. A weakness is only a weakness if it can be exploited, and in this case white won't really have anything substantial to go on after giving up the bishop. But why can I be so certain that white won't have any good follow-ups, even if I don't consider all possibilities? What aspects of the position make it clear to me that white will not be able to exploit black's "vulnerable" king?

If we look a bit more concretely at the position after Bxh6, gxh6, what do we find? We find an entire army of black pieces, all of them ready to leap into the defense of their king! In particular, the knight on f6 and the bishop on g6 are at least as good as a pair of pawns when it comes to shielding black's king from direct attacks, so it doesn't really matter that black's pawn cover isn't that great. Also worth noting is the rook on f8, which can be placed on f7, providing even more defense for black's king.

While it's good that you're aware of the fact that one always has to be careful with allowing this kind of sacrifice around one's own king, this needs to be tempered somewhat. Ask yourself questions like "how will my opponent follow up their sacrifice?", "can the opponent easily open up lines of attack against my king?", "do I have enough defenders around my king?" etc. and you will find it a lot easier to correctly judge whether a piece sacrifice with the goal of initiating a king assault is likely to succeed.
> 17 votes

# Answer
This won't work. When you make aggressive piece sacrifices like this to expose the enemy king, you need to be able to follow up. In this case the obvious follow-up moves are Ng5 and Qh5, but both g5 and h5 are protected by Black's pieces. You could try f4, but it's slow - Black is not obliged to capture and after \[pass\] 2. f5 Bf7 you are once again out of attacking ideas.

For such an attack to work you need more firepower. For example, if you had the queen on d2 such that you can meet 1...gxh6 with 2. Qxh6, the sacrifice might work. Or maybe if somehow managed to trade light-squared bishops (trading one of your inactive pieces for an important defender of the opponent), and had the king on h1 with rooks on f1 and g1. As it is, Black's king simply has too many loyal bodyguards for your few attackers to break through.
> 5 votes

# Answer
> black's king would be totally exposed if white's bishop decided to take the pawn

Having little pawn cover and being "exposed" are completely different things. Black has five pieces available for the defense of their king, while White has only four pieces available to attack. One of those pieces is the bishop whose sacrifice you're evaluating, one of them is the fianchettoed bishop that, thanks to White's e pawn, has been deprived of the long diagonal and will take awhile to get into the action, one is a knight that has no available moves, and one is a queen, and while queens are more powerful than the other pieces, they're also much less disposable. With White's dark-squared bishop gone, taking out the h-pawn is going to be far from trivial.

While the sacrifice will result in two half-open files next to Black's kings, they're half-open on Black's side. That is, at least in the short run, removing the g pawn simply clears the file for Black's rooks! There's no way White's getting their rooks in a position to take advantage of the files (especially the g file) without a huge amount of work, and the h and e pawns are going to be major impediments to any pawn storm. If White can trade their bishop for the g *and* h pawns and have their g and h pawns be passed, that would be much more of concern.
> 4 votes

# Answer
If I am white, the sac I am looking at is f4 !? Idea of possibly a recapture on g5 with the knight, threatening the fork and eyeing h7. Also f5 may be interesting, but it is hard for black to really do much about the f4 break so it is probably best to just retreat the bishop with f4 coming. Another good rule of thumb is to not make a speculative sacrifice when a simpler strategy will suffice. I could be wrong, but I think white is in good shape here, and my suggestion is mainly not worth it because the f4 break delayed is almost as strong so might as well have a bishop for the attack.
> 0 votes

---
Tags: positional-play, sacrifice
---


title: Video of Anand vs Kasparov from 1996

text:
# Question
Title: Video of Anand vs Kasparov from 1996
Where can I find a video of Anand vs Kasparov played at 1996 Las Palmas. There is a mention of it in this ChessBase article:

> At this point Kasparov went into a deep think. Jan Timman started to speculate whether White couldn’t play the very forceful 20.g4. Kasparov’s second Yury Dokhoian immediately confirmed: “That’s what he’s looking at!” Yury understands Kasparov’s thinking better than anyone else in the world.
>
> Meanwhile White had played 20.Bd5. The game lasted six hours, Anand defended very tenaciously and at around 10 p.m., much to the disappointment of Kasparov, a draw was agreed.
>
> When he left the stage Garry came into the press room, spotted me and walked straight over. “I couldn't win it, could I, Fred?” he asked, with a troubled look on his face. It was a bit shocking: the world champion and best player of all times consulting a chess amateur, asking for an evaluation of the game he has just spent six hours on!
>
> Naturally Garry wasn't asking me, he was asking Fritz. He knew I would have been following the game with the computer. “Yes, you had a win, Garry. With 20.g4!” My answer vexed him deeply. “But I saw that! It didn't work. How does it work? Show me.” I could not dictate all the lines, but then Yury walked over. Garry and Anand listened in horror while he gave them all the critical lines. All of this was captured on video and published in ChessBase Magazine 56

Also, from the same article:

> Yury Dokhoian checking the 20.g4 line with Fritz in real time during the game, Kasparov and Anand analyse after six hours of play \[video grabs from the CBM 56 multimedia report\].

This implies that there is definitely a video of this somewhere, but I was unable to find it.

# Answer
> 3 votes
This video was recorded by Chessbase and released with their Magazine 56 (stated here https://en.chessbase.com/post/remembering-yury).

So I guess you have to get your hands on this magazine for the video. You can try to contact Chessbase, maybe they will give you a link to the video, as it is quite old now.

---
Tags: kasparov, anand, chess-videos
---


# Question
Title: How feasible is 7.Qa4+ in this Ponziani sideline?
Recently I played a game with a fairly standard Ponziani opening when something slightly interesting occurred. The game started as thus:

```
[FEN ""]
1.e4 e5 2.Nf3 Nc6 3.c3 Nf6 4.d4 Nxe4 5.d5 Ne7 6.Nxe5 d6

```

6...d6 here is, of course, not the main line; 6...Ng6 is a stronger move for Black, still threatening a capture on e5 in a way that develops the knight while also keeping the king relatively safe. In the single game I found in this position, White (Daniel Klocker, 8/30/2008) proceeded to play 7.Bb5+, which Stockfish seems to think is the best move possible. It gives this move roughly a six point advantage for White. Meanwhile, in the game I played, I instead played Qa4+. Chess.com classifies this move as a "mistake", and while it still calculates the position as being advantageous for White, the advantage decreases to a measly +2.4.

Why is this a poor move, though? When I was playing, my logic was this: if they play b5, then I play Qxb5+. If they play anything else, then I play Qxe4. In hindsight, perhaps it would be better to play Qxe4 in any case, or to maybe offer a queen trade if Qd7, but it seemed sound at the time. What is the downside of this move that I'm not seeing? White's queen isn't under attack here, and frankly, I'm not sure why Bb5+ is better since it's easily blocked by c6, forcing White to retreat instead of developing further.

# Answer
6...d6?? is an horrible move.

White is totally winning because of the weakening of the a4-e8 diagonal. Choosing between several winning lines isn't always obvious, and the computer may call a winning move a blunder just because another possibility is even more crushing.

After 7.Bb5! Black can safely resign, since after 7...c6 8.dxc6 bxc6 (otherwise the discovery check wins a queen) 9.Nxc6 Qb6 (or 9...Nxc6 10.Bxc6 Bd7 11.Bxe4 win an extra piece) 10.Nd4 (10.Nxa7 or 10.Qa4 or 10.Qe2 are good too) Bd7 (10...Kd8 11.Qf3) 11.Bxd7 Kxd7 12.Qf3 White has a huge attack and a couple of extra pawns.

7.Qa4?! also wins, but after e.g. 7...c6 8.dxc6 bxc6 9.Nxc6 (or 9.Qxe4 dxe5 10.Qxe5 with "only" a safe extra pawn) Nc5 10.Nxd8 (or 10.Qb5 Qd7) Nxa4 11.Bb5 Kxd8 12.Bxa4 this is "only" an extra pawn and Black may play on in the cheerless endgame.
> 5 votes

---
Tags: opening, theory
---


# Question
Title: What is the longest possible forced checkmate sequence?
As title says. My question is about legal positions (positions which could be reached in actual games), but if there is a known solution with an illegal position to start the sequence, I'd be interested in knowing that too. Just to be clear, I'm not interested in the longest forced checkmate *in actual games*, but the longest *possible*. I do not necessarily mean "doubly forced", and I'm not interested in tournament rules like 50 move and other similar.

# Answer
> 2 votes
The answer is "yet unknown, but we have a known current record holder".

There are two main sources for records.

* Chess problems. The longest "mate in n" which is also testedly correct (in the pre-computer age there were even longer attempts) is around 300 moves. This is also probably the maximum - there are only so many Black pawn tempo moves and long zugzwang triangulations to give the move to Black, so you won't get much more than 300 moves that way (this even holds with positions which are illegal due to impossible chains of pawn captures). See also here on CSE.
* Table bases. By listing all mate positions, then working backwards (finding all mate in 1, then mate in 2 etc.), a computer can in principle know the value of any position without a doubt. For example KQ/K is at most #10 for any position. For time and space reasons, though, the table bases are currently known only for 7 pieces at most. This means:
* The current record holder for the longest mate *with ignoring the 50 move rule* was implicitely given by Allure in his link: 549 moves. I give another with some additional info: see here. EDIT: Newsflash! Make that 584 (contains a promoted B).
* Snag 1: If we now play by the 50 move rule, that game would have been drawn long ago. To my best knowledge, the record holder for this variant is unknown, and it would be quite a feature to repeat all the calculations. This would be best asked in a chess programmers community. We have a contender, though: see here on CSE, found accidentally.
* Snag 2: The 8-piece table base are fervently in the works, don't hold your breath. If you now expect any additional piece will break the record exponentially: Nope. An email with preliminary results by Marc Bourzutschky argues possible exchanges lower the record lengths, and for this reason the author expected we already are close to the natural maximum.

# Answer
> 2 votes
OP asks for the longest win under basic rules, so Snag 1 in @HaukeReddmann's answer wouldn't apply.

Records in chess problems have already been far exceeded in tablebases so far generated, so I think these can be discounted as a pointer to the answer.

The most convincing pointer I have come across so far is "Haworth's Law". (Guy Haworth sadly died very recently.) This is available via the following link: http://centaur.reading.ac.uk/36276/3/HaworthLaw.pdf

I reproduce it here.

I should note that the points shown on the graph for 3 to 7 men (8 to 10 are only predictions) form a better straight line than I ever managed in my physics pracs at school. Also the conjecture has so far proved itself as a predictive method. I believe it was first proposed on the the basis of the 3-4-5 man Nalimov tables and the values for 6 and 7 man tables have morphed from predictions into verified measurements.

The author wisely doesn't predict more than a few increments ahead, but I would say that the best *guess* for the longest mate with 32 men would be arrived at by extending the straight line already accurately measured by the EGTBs (as you would in verifying Boyle's law or whatever).

Because the y axis is a logarithmic scale this would give a longest forced mate with 32 men on the board of around 1.2 x 10¹¹ moves. (Not a footnote; twelve hundred trillion moves in American trillions.)

One possible snag here is that the EGTBs don't exclude all illegal positions and I imagine OP is looking for the longest forced mate from a legal position.

For the EGTBs produced so far this is not a problem because the maximal mates are all from legal positions. However starting from the 12 man EGTBs some of the endgame *classifications* become illegal (e.g. KQQQQQQQQQQK). This effect progresses as the number of men increases until by 32 men, although the number of classifications is enormous, the only one that contains any legal positions is KQRRBBNNPPPPPPPPKQRRBBNNPPPPPPPP.

It's not clear if that would affect the rate of increase. The straight line graph for legal positions could conceivably flatten beyond 12 men (though there's no reason I can think of to suggest it would). At any rate it's hard to imagine that the author's first conjecture could fail, so on the basis of tablebase results to date, it would be reasonable to assume the answer would at least exceed the intersection of Haworth's line with the 12 man ordinate, viz. about 25,000 moves.

A second possible snag may be "Snag 2" mentioned in @HaukeReddmann's answer.

I haven't seen the paper he refers to. I would be very grateful if he could actually dig it out.

Without further details this snag is less than convincing for two reasons.

The first is that the possibility of exchanges is already built into the tablebase results from the off. Obviously there are more exchanges possible in all 4 man endgames than there are in any three man endgames. Any trend apparent from the tablebase results should already take the possibility of exchanges into account.

The second is that in practice it becomes apparent that one of the major factors adding to the length of a mate is actually the necessity of *avoiding* exchanges. Anyone who has practiced queen v rook endings will probably have come to the conclusion that he could do the things faster if he didn't have to worry about the possibility of a queen for rook exchange.

OK, in that case he's swapping down. Here is another example where a maximal length mate in bishop & knight v knight is played by Nalimov. You will notice he has any number of opportunites to make an *equal* swap while Black's knight is on the board, but all such swaps would immediately draw.

```
[Event "?"]
[Site "?"]
[Date "2021.3.11"]
[Round "?"]
[White "Nalimov"]
[Black "Nalimov"]
[Result "?"]
[SetUp "1"]
[FEN "8/8/8/8/8/8/1n5B/2K1N2k w - - 0 1"]

1.Bh2-g3  Nb2-c4  2.Kc1-d1  Nc4-e3+  3.Kd1-e2  Ne3-f5  4.Bg3-f2  Nf5-e7  5.Ke2-f3
Ne7-c6  6.Kf3-g3  Nc6-d4  7.Kg3-g4  Nd4-b3  8.Kg4-h3  Nb3-c1  9.Ne1-c2  Nc1-d3  10.Bf2-b6
Nd3-f2+  11.Kh3-g3  Nf2-e4+  12.Kg3-f4  Ne4-d2  13.Nc2-e3  Kh1-h2  14.Kf4-g4  Nd2-b3  15.Bb6-a7
Nb3-c1  16.Ba7-d4  Nc1-d3  17.Kg4-h4  Nd3-f2  18.Bd4-e5+  Kh2-g1  19.Be5-c3  Nf2-e4  20.Bc3-e1
Ne4-f2  21.Kh4-g3  Nf2-e4+  22.Kg3-f4  Ne4-c5  23.Kf4-f3  Nc5-e6  24.Be1-c3  Kg1-h2  25.Kf3-g4
Ne6-c5  26.Bc3-e5+  Kh2-g1  27.Kg4-f3  Nc5-e6  28.Kf3-g3  Ne6-c5  29.Be5-d4  Nc5-b3  30.Bd4-a7
Nb3-d2  31.Ne3-c4+  Kg1-h1  32.Nc4-e5  Nd2-c4  33.Ne5-d3  Nc4-d2  34.Kg3-h3  Nd2-f3  35.Ba7-e3
Nf3-e5  36.Nd3-f4  Ne5-c4  37.Be3-d4  Nc4-d2  38.Nf4-h5  Nd2-e4  39.Bd4-e3  Ne4-f2+  40.Kh3-g3
Nf2-d3  41.Nh5-g7  Nd3-e5  42.Ng7-e6  Ne5-d3  43.Ne6-g5  Nd3-e5  44.Ng5-h3  Ne5-c4  45.Be3-f4
Nc4-b2  46.Bf4-d6  Nb2-d3  47.Bd6-e7  Nd3-e1  48.Be7-c5  Ne1-d3  49.Bc5-d4  Nd3-c1 50.Kg3-f3
Nc1-d3  51.Nh3-g5  Kh1-h2  52.Bd4-c3  Nd3-c5  53.Bc3-e5+  Kh2-h1  54.Be5-d4  Nc5-a6  55.Ng5-e4
Na6-c7  56.Ne4-f2+  Kh1-g1  57.Nf2-d3+  Kg1-f1  58.Nd3-f4  Kf1-e1  59.Kf3-e3  Nc7-a6  60.Bd4-c3+
Ke1-d1  61.Ke3-d4  Kd1-c2  62.Nf4-d5  Na6-b8  63.Kd4-c4  Nb8-c6  64.Nd5-e3+  Kc2-c1  65.Kc4-d5
Nc6-b8  66.Kd5-d6  Nb8-a6  67.Kd6-c6  Na6-b8+  68.Kc6-c7  Nb8-a6+  69.Kc7-b6  Na6-b8  70.Bc3-g7
Nb8-d7+  71.Kb6-c6  Nd7-b8+  72.Kc6-b5  Nb8-d7  73.Ne3-d5  Kc1-d1  74.Nd5-b4  Nd7-b8  75.Kb5-b6
Nb8-d7+  76.Kb6-c6  Nd7-b8+  77.Kc6-c7  Kd1-e2  78.Kc7xb8  Ke2-e1  79.Kb8-c7  Ke1-f2  80.Kc7-d6
Kf2-f3  81.Kd6-e5  Kf3-e3  82.Nb4-d5+  Ke3-f3  83.Nd5-f4  Kf3-e3  84.Ke5-f5  Ke3-f2  85.Kf5-e4
Kf2-g1  86.Ke4-f3  Kg1-h1  87.Nf4-h3  Kh1-h2 88.Nh3-f2  Kh2-g1 89.Bg7-e5  Kg1-f1 90.Be5-h2
Kf1-e1 91.Nf2-e4  Ke1-d1  92.Bh2-e5  Kd1-e1  93.Be5-d4  Ke1-f1  94.Ne4-d2+  Kf1-e1 95.Kf3-e3
Ke1-d1 96.Ke3-d3  Kd1-e1  97.Bd4-c5  Ke1-d1 98.Bc5-f2  Kd1-c1 99.Nd2-c4  Kc1-d1  100.Nc4-e3+
Kd1-c1 101.Kd3-c3  Kc1-b1 102.Kc3-b3  Kb1-c1  103.Bf2-e1  Kc1-b1 104.Be1-d2  Kb1-a1 105.Ne3-c4
Ka1-b1 106.Nc4-a3+  Kb1-a1 107.Bd2-c3#

```

It may be that more cogent reason's are given in the actual paper. There is obviously a discrepancy between the paper @HaukeReddmann mentions and the predictions given in Haworth's paper but at least we don't have to wait for the end of the universe for a resolution. Haworth predicts that the 8 man tablebases should throw up a mate that needs at least 1200 moves, so the resolution should arrive with the completion of those tablebases (assuming they're DTM tablebases).

---
Tags: theory, problems, checkmate, forced-move
---


title: Search function for chess engines

text:
# Question
Title: Search function for chess engines
I'm creating a bitboard based chess engine in c++ and I'm trying to write the search function. It currently looks something like this

```
double search(Position& pos, int depth, double alpha, double beta) {
    Move_list move_list = Move_list(pos);
    double evaluation;

    if (move_list.size() == 0) {
        if (check(pos)) {
            return -1024;
        }
        return 0;
    }
    if (depth == 0) {
        return eval(pos, true);
    }
    for (auto& m : move_list) {
        do_move(pos, m);
        evaluation = -search(pos, depth - 1, -beta, -alpha);
        undo_move(pos, m);
        if (evaluation >= beta) {
            return beta;
        }
        if (evaluation > alpha) {
            alpha = evaluation;
        }
    }
    return alpha;
}

```

Now I have a couple of problems. Say I do a search on the position "k7/8/8/8/8/8/7R/1R5K - w -". We obviously have a mate in one with h2a2. The search function however "sees" that there is no way for the black king to escape, so it just shuffles pieces around because it knows it can deliver mate whenever it wants to. One solution to this problem would be to prioritize checks if two moves have the same evaluation, but it is kind of an ugly solution and I'm sure there are other positions where the same problem occurs but the first move is not a check (say a mate in 2 of some sort).

Another solution would be to first do a search of depth 1. Order the moves so that the highest evaluated move comes first and then do a search of whichever depth we want. This would mean it always makes the move with the best evaluation, but if there are 2 moves with the same evaluation it prioritizes the move which gives the best evaluation on the next move.

Maybe this would be even more effective with alpha beta pruning if I do a search of depth 1, then 2 all the way up to the depth we want. This seems counterintuitive, but would it be faster because of the reordering of the moves at each depth?

If this is the way to do it, how would I even go about writing such a search function. Would it then also take as an argument a reference Move\_list to reorder it? If any of you have code of your own to solve this problem I would love to see it!

# Answer
> 2 votes
One possible approach is to decrement the evaluation for a mate score. For instance:

```
evaluation = -search(pos, depth - 1, -beta, -alpha);
if (evaluation > 900) {
    evaluation--;
} else if (evaluation < -900) { // you could also drop this case
    evaluation++;
} [...]

```

This way your program can tell apart a mate in 1 from a mate in 3. It will choose the fastest mate and you can even calculate the distance to mate from the evaluation given.

Worth noting eventually you might still want to reorder the to be searched moves in the original position since alpha-beta search becomes more effective if you search the best move first. One option might indeed be to pass those so called root moves as a parameter though there are other solutions of course. (usually you would have a different function for that too, so for instance *root\_search* which then calls the normal *search*) However, that is a problem for another day.

---
Tags: engines, programming, bitboard
---


# Question
Title: Why do pro chess players look up (look at the ceiling) when waiting for their move?
When players like Magnus Carlsen and Viswanathan Anand finish their move, they sometimes look up while they wait. Shouldn't they be looking at the board to see their next move?

# Answer
> 43 votes
When you're that good at the game, you do not need to look at the board to have a complete understanding of the position. Especially just after your move is when you're more likely to be visualizing positional considerations and not directly calculating variations. So your thoughts are more general and do not depend on the specifics of the current position.

Moreover, looking at the pieces on the current board can be a distraction from the lines you are visualizing in your head. If a bishop is on d3 on the board in front of you, but you are calculating what happens when you play Bxh7+, you can sometimes get confused and falsely visualize having another bishop on d3 if you directly look at the board while calculating.

# Answer
> 6 votes
Many many people will look off into the distance or up in the sky when they are trying to recall something or to visualize something. At least at the start of a chess game, strong players are often trying to visualize and recall the exact move order of one or more "opening lines" that is favorable to their color. These are a very precise series of moves that must be executed in the exact order to assure arriving at a position where they will have an edge or where they have decided to introduce a novel move. So there is a lot of mental "making sure".

Also, there are usually monitors showing the position as a 2D diagram over each pair of players on the stage, and some players actually prefer that view to a 3D view.

---
Tags: carlsen
---


# Question
Title: On an 8-by-∞ board, who wins between an infinite number of pawns and a rook?
I've had this puzzle rattling around in my brain for the past few days and I want to know what you all make of it.

Imagine chess played on a board with eight ranks and an infinite number of files. Black has a single rook on a1. White has an infinite number of pawns, one on every square in the first rank besides a1.

The rules here are slightly different from normal chess.

> 1. White's goal is to capture the rook. Black's goal is to never get captured.
> 2. White's pawns can only move one space forward and never have the option to move forward two spaces. They still capture diagonally.
> 3. White may move one pawn off of the first rank, and any number of pawns already off the first rank simultaneously (notated with an ampersand).

Is White guaranteed to capture Black's rook at some point in time, or does Black have a strategy to survive? I *think* White has a guaranteed victory, but I can't say for sure. Consider the following string of moves.

```
1.b2 Rxc1
2.b3&d2 Rxe1
3.b4&d3&f2 Rxg1
4.b5&d4&f3&h2 Rxi1
5.b6&d5&f4&h3&j2 Rb1
6.b7&d6&f5&h4&j3&k2 Rxb7
7.d7&f6&h5&j4&k3&l2 Rxd7
8.f7&h6&j5&k4&l3&m2 Rxf7
9.h7&j6&k5&l4&m3&n2 Rxh7
10.j7&k6&l5&m4&n3&o2

```

Now Black is stuck. If they play 10... Rxj7, then White follows with 11. kxj7 and wins. If they do anything else, then 11. j8=Q is sure to follow, which spells out doom for Black. Does Black have a more optimal strategy that leads to their survival, or is this it?

# Answer
> 2 votes
It is trivially a win for white even on an 8x8 board

```
[fen "8/8/8/8/8/8/8/rPPPPPPP w - - 0 1"]

1. h2 Rxb1 2. g2 null 3. h3 Rxc1 4. f2 null 5. g3 null 6. h4 Rxd1 7. e2 null 8. f3 null 9. g4 null 10. h5 Re1 11. e3 null 12. f4 null 13. g5 null 14. h6 Rxe3 15. f5 null 16. g6 null 17. h7 Rf3 18. f6 null 19. g7 null 20. h8=Q Rxf6

```

# Answer
> 0 votes
The "trivial" white wins solution has been refuted by the fact that the "win" is actually a loss. You can't construct a mate even without figuring out a forcing sequence of moves. The infinte board is another story. Black will need to figure out a different way to stop white when she has to go through an infinte number of pawns. I am not 100% convinced that there isnt some way to stop white with the rook other than brute force pawn gobble, and on an infinte board that ain't gonna work. It feels like white should win on an infinte board - but before coming to this conclusion, there are possibly other options which dont begin with ...Rxb1. I couldn't find any way to stop the pawns without going for the "let him only get 2 queens " strategy, but I certainly didn't exhaust all the possibilities.

---
Tags: chess-variants, puzzles
---


# Question
Title: What prevents chess engines from being undetectable?
I see accounts of people getting banned from sites like chess.com for using engines like Stockfish and Komodo (I admit I have used these engines before, but never in an actual match). Now, I believe there are certain characteristics of these engines that make them easy to detect. One I heard is the way you move the King, as well as every move being the best move possible (This one could be wrong). But I was thinking... couldn't chess engines not do the things that make them detectable, like play Kings less randomly, play sub-optimal moves in between optimal ones, etc, and become basically, as far as I can notice, undetectable? Is there anything about the way they are programmed that make this impossible or is this because of legality and morality?

# Answer
> 31 votes
1. Engines have no concept of natural moves and they have no fear. An engine will play for the most advantage, not for the most manageable advantage, even if it allows a fierce attack, because it sees that the attack does not work, while a human would probably prevent an attack and settle with a smaller, but practical advantage.
2. "Randomly" picking good moves is not easy. The second best move may only be second best if you see a very hard ONLY MOVE which comes 15 moves after. And sometimes, the best move is very obvious, and playing the second best move would be very suspicious.
3. It is not very known how engine detections on chess websites work, but I have read that they also account for playstyle inconsistency (ultra-aggressive to defensive, even though an aggressive move is available and not much worse), mouse movement, time management.

# Answer
> 16 votes
One very obvious indication for people using engines is, that they need roughly the same time for every move (usually about 5s in blitz games), even for the most obvious ones, which could be premoved. They also have much worse ratings in faster time controls (bullet). One example: https://youtu.be/rlxHusHfpck

# Answer
> 12 votes
Some of those things are possible in theory. Especially if you have a good idea what an engine-detector is looking for, you could maybe do some machine-learning training of algorithm against algorithm until you had one that could make good moves that didn't get detected as different from a given player's normal play.

**But that would require someone to be interested in spending a *bunch* of effort to make software whose main use-cases included letting people cheat undetectably**. Most people actively don't want that and would avoid doing so, even though there might be other uses (like for training, to play against a human-like opponent, if it's good enough to *really* play human-like, not just sneak under the anti-cheat radar).

So I think a significant part of what prevents that from happening is the ethics / moral code of many software developers. Or that **for most people it's a somewhat less interesting goal** than making a strong chess engine by any means possible. Not purely technical challenges *if* someone set that as a goal.

OTOH I could imagine some people might be curious to see if they could teach an engine to play more like a human, or play more like a *particular* human. And/or as @Akavall mentions, as a training opponent. That could make for some interesting research, although the danger of cheaters weaponizing the results would hopefully deter many researchers from pursuing it.

# Answer
> 5 votes
That's a bit like asking a congregation of people "is everyone here?" and expecting an accurate answer.

There may very well be chess engines that are optimized to fly under the radar of the cheat detection algorithms used at the major sites. But those are not the ones that get exposed and therefore they are not well known.

# Answer
> 4 votes
With the proliferation of machine learning systems and excess processing power, once you have enough play data, you can use readily accessible machine learning algorithms to determine a player's playstyle, and compare their moves against chess engine playstyles.

The exact mechanism and detail are university-level courses, so that isn't something I can explain in detail at the moment, but having access to a large amount of chess play data would make such analysis easily doable for someone in 2nd or 3rd year in computer science or data analytics. Machine learning is accessible enough that I think even a high schooler with particular interest would be able to do the analysis.

# Answer
> 0 votes
in esports (other esports? lol) like csgo, there are hundreds of sites dedicated to cheating. i have a feeling there may be a few such sites similar dedicated to chess cheating but ultimately i think it would end up the same as csgo: for every cheat, the csgo peeps will eventually improve their systems to counter the cheat. i have a feeling the case is similar to chess except i think it's much less difficult to counter cheats in chess as compared to games like csgo.

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Tags: engines, online-chess, programming
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# Question
Title: Why do women have a lower Elo requirement to obtaining (women) FIDE titles?
As well as FIDE norms, you need a certain Elo to obtain a certain title. Women need around 200 points lower Elo to obtain the analogous women's only title:

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* Grandmaster (GM) 2500+
* International master (IM) 2400+
* FIDE master (FM) 2300+
* Candidate master (CM) 2200+

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* Woman grandmaster (WGM) 2300+
* Woman international master (WIM) 2200+
* Woman FIDE master (WFM) 2100+
* Woman candidate master (WCM) 2000+

---

I have read many times the reason why women don't reach the super GM level is social and not cognitive. For example in this interview to WFM Rodrigo she is asked:

> XL. Why are there still no women in the elite?
>
> M.R. For various reasons, but basically for two. For a statistical question (we are less players) and for a cultural factor. Evolutionarily, women are more used to collaborating and men to compete. It is an imprint that comes to us from the hunter-gatherer tribes. In addition, the male brain processes visual information faster, which favors the recognition of patterns on the board, while women have more developed memory. But in ten years we will see girls fighting for the world title.

So why is FIDE giving titles to women with less chess knowledge than players who have the equivalent open title? I know there are fewer women players than men, but women can play in men's tournaments.

# Answer
> 8 votes
I think WFM Rodrigo is correct when she says that the reasons are statistical and that having fewer female players means having far fewer players at the top.

If you assume that males and females have the same mean and standard deviation (we shall see soon that this assumption is false) and you draw the two normal curves you see that the curve with fewer members (females make up only 15% of FIDE registered players) tails off to zero long before the one with more members.

However WFM Rodrigo also mentions "cultural" reasons. Translated into mathematical terms I think she is suggesting that females have a lower mean (average) FIDE rating than males. This we can check by loading the latest FIDE rating data into a database and doing some SQL queries.

Doing that gives us:

**Female**
Mean = 1505, standard deviation = 339

**Male**
Mean = 1675, standard deviation = 346

We see that there is little difference between male and female standard deviation but the mean female ELO is 170 points lower than the mean male ELO. This is half a standard deviation which is a lot. It looks to me that WFM Rodrigo is right about this too.

Comparing these figures with the rating differences between the open (there are no male only titles) titles and the female only titles it looks like FIDE are being generous to the females by a margin of 30 points. Perhaps they rounded the difference up to the nearest hundred?

# Answer
> 7 votes
**Note**: This addresses the previous revision of the question w/c said 'Women need less ELO to obtain the same title than men.'

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It's not the same title. Women Grandmaster (WGM) for example is clearly less prestigious than GM because the requirements are lower. FIDE isn't giving out the same title to women who have less knowledge than men, they are giving out exclusive titles for women. In the same way there are female players who have achieved the actual GM title (e.g. Hou Yifan is a WGM *and* a GM).

As for why they would do that - why not? Chess is heavily male dominated, and a WGM title makes the game more inclusive. Can you think of a good reason not to have the titles?

# Answer
> 2 votes
I suspect it's related to why women can compete in **women's chess championships without being a GM**.

* Eg 1 the US women's chess championship or the british/UK women's chess championship have been recently won by non-GMs: Nazí Paikidze, Jennifer Yu, Sabina-Francesca Foisor, Jovanka Houska (current), Akshaya Kalaiyalahan.
* 1.1. The current US women's champion is GM Irina Krush, who has last been champion for 2012-5. However for 2016-9, Krush participated in all, but besides that e didn't win, actually none of the winners were GMs! See for yourself: 2016, , ,
* Eg 2 Wait actually I just looked up to be sure and apparently WGM is even good enough to compete in the *world's* women chess championship:

You can see this as like 'semi-begging' the question in the sense of converting to another question on women's chess championships, but as for this current question...

**Conclusion**:

I think these recent results show (well at least for the UK and the UK/Great Britain) that **'WGM' as in '2300+'** (and norms or whatever else is required) **is good enough to compete in** (at least local/national if not international) **women's chess championships**.

So, if we suppose on the contrary that we didn't/don't have women's titles, then **we'd be describing winners/runner-ups of women's chess championships as just FMs**. I believe the **WGM title would be more descriptive** for these winners/runner-ups.

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**Bonus**:

1. Of course, you can argue, since/if/if it would be that many WGMs now/later on as compared to before are also IM, that we might increase WGM to 2400+ from 2300+ so as to distinguish a WGM like Nemo Zhou \[see here\] from a WGM like IM Jovanka Houska (current British women's champion), but that's another story.
2. If in the future winners/runner-ups of women's chess championships and even most participants are GMs, then who knows maybe requirements for women's titles will increase, maybe even to the point that they will be the same as the open titles (and thus there would not need to be women's titles).

# Answer
> 0 votes
I think they can have the same requirements if there were more women exclusive tournaments. In this way it's less difficult to obtain say 2500+ for WGM if women play only other women as compared to getting 2500+ if women are up against both men and women.

Plainly, there are not so many of these tournaments, so the next best thing is to just do make the requirement lower.

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Tags: fide, psychology, elo, titles, women
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title: Is castling good in Chess960?

text:
# Question
Title: Is castling good in Chess960?
The overall arrangement of the pieces in Chess960 seems so weird that I have a question about it: should there be castling at all?

# Answer
> 4 votes
Yes, castling is good, especially when you are about to be attacked by say, a knight and queen, a king castling to the other side is very good.

# Answer
> 3 votes
Another reason why castling is good in 960 chess (and classical chess) is that it **connects the rooks**.

In the following example, Black quickly castled and connected his rooks, while White did not. This is not the only reason for White's defeats, but it is part of it.

```
[fen "nqbbrkrn/pppppppp/8/8/8/8/PPPPPPPP/NQBBRKRN w - - 0 1"]
[title "Shankland - Vachier-Lagrave, Champions Showdown, Chess 960 2018"]

1. d4 d5 2. c3 Ng6 3. Bc2 c6 4. Ng3 O-O 5. h4 f5 6. h5 f4 7. Nf5 e6 8. Nxg7 Kxg7 9. hxg6 e5 10. dxe5 h6 11. Nb3 Qxe5 12. Bd2 Nb6 13. Qd1 Nc4 14. Nd4 Ne3+! 15. Bxe3 fxe3 16. Nf3 exf2!! {Brillant sac of the Queen} 17. Nxe5 Bh4! {and mat follow soon} 18. g3 Bh3+ 19. Rg2 Bxg3! 0-1

```

# Answer
> 1 votes
In chess870, the answer is that the principles of castling in regular chess still apply. This is similar to asking if you should still control the centre, develop knights before bishops, etc.

What I haven't found to be discussed online (or even in Wesley So's chessable course) however is for the 90 positions of chess960 where castling on one side requires moving (or removing by a capture) a rook on the other side.

Sure the principles still apply, but I haven't yet found some article or video that gives some examples explaining whether or not you should give up castling rights on 1 side by moving that side's rook in order to castle on the other side.

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Tags: chess-variants, castling, chess960
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# Question
Title: Why is it illegal to castle with both hands?
I was watching the match between Ian Nepomniachtchi vs Hikaru Nakamura and Nakamura used both hands to castle.

Why is it illegal to castle using both hands? What's wrong with that?

# Answer
> 77 votes
The official procedure to castle is (Schiller 2003:19–20 from Wikipedia):

> first move the king with one hand and then move the rook with the same hand.

By using both hands the player can save time, as would by as using different hands for moving (like promoting a pawn to queen) or moving with a hand and hitting the clock with the other.

# Answer
> 65 votes
Disclaimer: this is probably not the answer, but it makes for interesting thinking.

This reminds me of a string bet in poker. String bets are illegal, because they can be used to gain information – “I’ll see your $5”… \< watches opponent’s face\> "… and raise you $20”.

By moving the king first, you are making what would otherwise be an illegal move (moving the king by more than one square) and cannot “string bet”.

If you were to move the rook first, you might observe your opponent’s face, then quickly choose to move the king, claiming that you had intended to castle all along.

# Answer
> 34 votes
I know in general the rules say the hand you move your piece with has to be the one that hits the clock. If you castled with two hands which one would you use to hit the clock? This might be part of the reason for the rule saying you can only castle with 1 hand.

# Answer
> 32 votes
Chess rules are all about sequence. If you use two hands, you don't know which happened first. So you always use one hand. First, you make your move, then you hit the clock.

As others have pointed out, the rook move alone could be one or two moves. Maybe, you were just moving your rook, maybe you were castling. The King move, however, does determine the one and only move. There is no other King move that allows the King to move two squares. By moving the King first, then moving the rook, there are no questions as to the real move. The Rook, while being part of the move, is forced. Because this is a sequence, you have to use one hand to play it.

As a side note, if you could use both hands, and you were playing with a clock, you could move the rook and hit the clock with one hand, and move the king with the other hand, and then there would be a sequence argument whether the king had moved before or after the clock hit, and thus whether it was a rook move or a castle. By requiring one hand to do all three (king, then rook, then clock), there is no question as to what went on. The king moved two squares first. That defined the move. Then the rook moved (with the same hand), then the clock was hit after the board was in a valid situation. No arguments.

# Answer
> 15 votes
> why is it illegal to castle with both hands?

Because the rules say so.
From the FIDE Laws of Chess -

> 7.5.4 If a player uses two hands to make a single move (for example in case of castling, capturing or promotion) and pressed the clock, it shall be considered and penalized as if an illegal move.

# Answer
> 11 votes
There is a very important rule for castling with one hand. In the Fide Handbook it is rule 4.1.

> 4.1 Each move must be made with one hand only.

The rule applies for all parts of the move, including capturing, castling and promoting.

Now for the reasoning, of why a move needs to be executed with exactly one hand: In case that you are making an invalid move there are specific rules on how to proceed after taking back the invalid move. As a general rule you have to move the first piece that you touched (rule 4.3.a). In case that you use both of your hands for castling, it would be pure luck to say that you need to do another king or rook move. Instead the order is clear. You first touch the king (and move it two squares). Then you touch the rook and move it to the other side of the king.

And why do you have to move the king first? Again it is to reduce any ambiguity. If you'd move the rook next to the king (without touching the king) you already completed a legal move. Castling now would be very weird as for the only time in chess a completed move could still be extended. Your opponent therefore could already make his move and you could still go: "I'm not finished yet, please take back your move". (In an extreme case you could wait for all the time on your clock before announcing that you are castling).

For these reasons it is important that you execute the castling in two steps (first king, then rook). The additional rule that you can only use one hand is not of practical importance as long as both parts of the move are clearly distinguishable.

# Answer
> 6 votes
It would permit a rather interesting ambiguity on the board.

Many have mentioned that the king has to move 2 spaces first, so that there's only one possible valid thing to do. So let's assume we do this.

With one hand, move the king two spaces. Once the king is in place (proving you intend to castle), the other hand grabs the rook and moves it. Meanwhile, the first hand goes to hit the clock.

It is possible that the first hand hits the clock before the rook is moved. Now you have a really funny situation where your hands are still moving pieces *while it is the opponent's turn*! Needless to say, this could be a big deal, especially if the winning move is to take that rook.

To avoid this case, one needs rules which ensure that all pieces are in their final position before the clock is pressed. Whatever rule FIDE chose, this is the key requirement placed on that rule. Hands off the board when it's not your turn!

If we use pi caluclus we can define a process where the clock press must occur after both moves are complete, regardless of which hand does what. So in theory, one might define a different rule which permits two-handed operation. However, in real life practical situations, such definitions are unreasonable. They work great with transistors and wires, and less well with human hands. Instead, we simplify the process by not allowing things to happen in parallel.

# Answer
> 3 votes
In chess, whenever you touch a piece, you MUST move that piece. If you were to begin castling using two hands, and then removed your hands, it would be unclear which piece you would be required to move. This is why it must be done with one hand.

# Answer
> 2 votes
It's because you can't save yourself time by moving with more than one hand like that. Imagine one minutes where people did that. Castle would be over powered for time management reasons. Therefore, you castle with one hand, and the problem is avoided.

# Answer
> 2 votes
This is speculation, but I think it's because FIDE wants to reduce the difficulty of knowing whether the rules are followed. One must use the same hand to move the piece and hit the clock because FIDE wants people to not hit the clock before they finish their move, and if different hands were used for the two actions, it could be unclear which happened first. And if someone uses both of their hands for a move, then clearly at least one of the hands used in the move will be different from the one used to hit the clock, making it difficult to see whether the other hand completed its portion of the move before the clock was hit. And it's not just what is easy to see, but what is clearly distinct. If we're trying to decide which hand completed its motion first, that is a matter of perception. But if we're trying to decide whether two hands were used, that's a clear binary. It's easy for two players to have differing opinions as to which hand completed its motion first, but whether two hands were used is an objective fact, and if the players disagree, that strongly suggests that at least one of them is just straight up lying.

# Answer
> 0 votes
I think the reason is a side effect of only being allowed to use one hand to make moves and to hit the clock. Otherwise in mutual time pressure it would be easy to end up making multiple moves when one is only allowed to play one before the opponent gets a go. Multiple hands could more easily support intentional cheating or create situations that an arbiter would find difficult to unwind if summoned

# Answer
> 0 votes
Legal is relative. It's illegal in FIDE rules as you can see with other answers.

But actually it's legal in American rules, at least in USCF rules in 2015. See what Hikaru Nakamura said in 2015.

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Tags: rules, castling, illegal-move
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# Question
Title: Why is 'Elo' sometimes capitalised to 'ELO'?
Why is 'Elo' as in Elo rating system sometimes capitalised to 'ELO' when it's a last name and not an acronym? I notice people don't say GLICKO, for example.

Some (heavily downvoted) reddit posts:

1. Stop capitalizing Elo
2. PSA: "Elo" is named after the mathematician Arpad Elo, it is not an acronym and should not be capitalized, e. g. "ELO"

Other uses of ELO

1. Chessboxing database: Eg David 'Northern Powerhouse' Jarmany
2. Gotham chess (levy rozman) says here

'You'll benefit from the course if your ELO rating is at least 900' and 'This course is designed for players who know the fundamentals of chess. They have an ELO rating somewhere in range of 800-1500.'

**Edit**: I am asking why people do things in a certain way. why opinion based? sounds pretty factual to me: I'm not asking what *should* be the case. I'm asking why certain things are the way they are.

# Answer
People simply don't recognize Elo as being a last name; it's Hungarian, which is completely unrelated to English. People do recognize ELO as a rock band so it's not strange to think of it as an abbreviation, especially since some kind of chess ratings (FIDE rating, USCF rating) *are* capitalized. I guess this happens with many three and four letter words, so that explains why you never see GLICKO. That is just more recognizable as a proper name.
> 8 votes

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Tags: rating, elo, terminology, glicko
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# Question
Title: Starting into chess in a foreign country
I am chess enthusiast living in foreign country, ie. I hold a citizenship from another country (let's say A) different from my residence (call it B). I would like to start into chess tournaments in the country where I live (ie. country B).

Can my citizenship/nationality be an obstacle?

I am asking because I contacted the organizers of a local chess tournaments, and they are asking me two requisites:

1. get a federation card for the hosting country (that is B),
2. but also, being a foreigner, to provide a FIN (I guess that means FIDE ID Number) from my home country (A).

To me the second request doesn't make any sense. I have never played in chess tournaments in my home country, I am not registered in their chess federation and I even don't live there since more than 6 years.

# Answer
> 6 votes
As someone who has also been in your position I can tell you that if you play in an official (nationally) rated competition in country B then you need to join their chess federation and pay the appropriate level of membership. This helps pay for running chess in that country. Sometimes the charge is disguised by you paying a higher entry fee for the tournament than somebody who is a member.

If you play in a FIDE rated tournament then you have to be a FIDE registered player with a FIN. The federation is responsible for making sure that unregistered players do not play and the federation is fined by FIDE if they break this rule. Like the national chess federation, FIDE costs money to run.

However the national federation is also responsible for registering players in that country. This can be done after the tournament is played as long as it is done before the tournament results are submitted to FIDE and most federations will do this provided they have your details, full name and date of birth.

For nationals of that country this is normally an automatic process. However if you are a national of another country you may prefer not to have FIDE registration with a different country and your permission is usually required by the federation before they "adopt" you.

Note also that while some countries are a bit backward regarding FIDE rating - most of their competitions are nationally rated only - in some countries all adult and most junior tournaments beyond weak players are also FIDE rated. In these "full FIDE" countries the only reason that tournaments for weak juniors are not FIDE rated is because they want to relax rules around number of illegal moves and use of clocks.

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Tags: fide
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# Question
Title: Is the average online account underrated in chess960?
I'm going to use lichess as an example, but I believe this applies to chessdotcom too. (I think it's better to use lichess as an example anyway because lichess and statistics for Chess960.)

It looks like the average Chess960 player (with non-provisional rating) is (significantly) **underrated**. Or even that the average player is underrated in Chess960. For a specific definition of underrated, let's try **at least 100 points**. See for yourself in

1. **seeking for a casual/rated Chess960 game**. I bet the 1st person who matches with you and who is non-provisional is going to be underrated (relative to the time control. For example if you do blitz challenge, then I think their standard blitz rating is going to be higher than their Chess960 rating).
2. **these lichess groups**: Fischer Random Chess Center and Chess960. I bet a random sample will show you that among the people with non-provisional Chess960 ratings, you can see that their standard ratings, whichever are also non-provisional, are going to be higher than their Chess960 ratings.

**I think this is problematic** because regular Chess960 players who are, say, 1500-1699 will may have to face people who are like 1200-1699 but their corresponding standard ratings are like 1600-2099. It would be like playing against sandbaggers.

* **An example** of what may happen is that the regular Chess960 players get in a position where they have to play for a win when they could otherwise force some repetition or perpetual. The position doesn't even have to be drawish. It could be winning for the regular player, but they have to think a lot to make the winning moves and risk making losing moves, when they could instead think less to make drawish moves.

**As to how this might arise**: If I am 1530 in blitz standard but 1220 in rapid standard, then let's say I play some Chess960 rapid and get to 1200-1249. Then I decide to play blitz Chess960. I am likely to beat a 1450 in Chess960 in a Chess960 blitz game. In this way, I am underrated because my Chess960 rating represents my rapid strength yet I am playing a blitz game.

**Question**: Assuming the above statistics are correct, is the average online player (say in lichess or whatever) indeed (significantly) underrated in Chess960? Or...

* ...or are they actually not considered underrated because in the 1st place lower rated players are unlikely to play Chess960? (Imagine superGMs create new accounts in lichess specifically to play against only other superGMs. Maybe no one would really reach 2500 assuming they all played seriously.)

Related:

1. Relation between ratings for Chess960 and standard chess
2. Farmbitrage: Fixed starting rating for chess960 causes loophole to easily get 2000 rating?

# Answer
> Is the average online account underrated in chess960?

No.

You appear to not understand the basic principle of chess ratings. They are not absolute measures of playing ability. They are relative. If player A is rated 2000 and player B is rated 1000 on the same platform, format and time control, then it should be safe to say that player A is a better player than player B at that format and time control. It tells you nothing about their absolute abilities.

The only way in which ratings on different platforms are in any way comparable is that if on platform X player A is higher rated than player B at a given time control and format then you would expect the same to be true on platform Y at the same time control and format.
> 4 votes

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Tags: rating, chess-variants, chess960
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