# Question
Title: Bughouse sitting/stalling full strategic breakdown
We play with the rule one loses -\> the team loses. My cheesy titled question is serious: let's try to wrap our heads around the Bughouse clock mechanics. When should one consider sitting/stalling? I imagine these ones:

* I sit because the opponent mates me in the next move.
* Because moving would mean giving my opponent a chance to capture a piece of mine, giving his partner a piece he needs and improves his game a lot.
* To wait for a piece my opponent could handle me that could give me huge advantage.

Also, for stalling/sitting we always need more time that the diagonal opponent, if not, he could stall and we lose by time.

Are there other reasons to sit/stall?

# Answer
Well, since the values of pieces in bughouse chess depends severely on the position type (e.g. a queen is often useless) you may want to stall/not play immediately when you're waiting for a specific piece to complete your strategy in general, not necessarily to win you a piece or gain some specific advantage.

E.g. you may have noticed experienced bughouse players starting with 1.Nf3 followed by Ng5 or Ne5 and sacrificing at f7. Now, when the king takes the knight, you might not reach an immediate advantage, but getting a knight could yield you a nice aggressive position. Or another example would be waiting to get a pawn very early to disturb your opponents development as early as 2nd or 3rd move, with the goal of attacking, but also getting more space and a psychological advantage. While we're on that, sometimes if you're playing blitz bughouse casually, chatting etc. you might want to spend some time just to get your opponent off track, since psychology plays a huge role in chess, and therefore in bughouse as well.

However, I would agree with you that on most occasions it is that you see you're getting checkmated in the next move so you let your partner play as long as he can(given that you have more time than your diagonal opponent, of course).

That's pretty much all I can think of, I hope you find this answer useful!
> 2 votes

# Answer
I will give an (impractical but I think interesting) answer to when it **theoretically** makes sense to stall in Bughouse, since on a mathematical level this is a definitive factor in the game.

In particular, let a position on one of the boards be 'winning' when, *assuming no further pieces are incoming from the other board*, the position is theoretically won with optimal play on that board (given the board-state + pieces in hand for both players). Then there is the following lemma:

Consider players A1 vs B1 on board 1 and A2 vs B2 on board 2. If the position becomes winning for A1 on board 1 (and A2 expects A1 to successfully obtain the win), then A2 can assure the win with no further cost in game-complexity simply by stalling **if** the clock time remaining for A2 is greater than the clock time available for B1 *plus* the time A1 will need to force the win against B1.

Why? Because if A2 stalls while having less time than B1, for example, B1 always has the option of themselves stalling, and A2 needs to outlast B1 or else his flag will fall before *either* B1's flag falls or B1 is mated by A1.

If you (any human pair) were to play theoretically-optimal opponents, expect the game to last only briefly across both boards. Then one board falls silent with stalling; that's when you know that on the other board they've spotted a forced win.
> 2 votes

---
Tags: chess-variants, bughouse
---


# Question
Title: What is the meaning of 'fighting draw' vs 'draw by theory' in re Chess960?
I remember reading in some YouTube comment that Chess960 will lead to less draws or something. There was a comment response saying that it seems about the same. Then the original commenter replied in a correction that it may actually about the same but in Chess960 the draws will be 'fighting draws' and that compared to standard chess there will be less 'draws by theory'.

**Question**: What are the meanings of 'fighting draw' and 'draw by theory' ?

**Guess**: Draw by theory means 'quick draw' ?

After watching and reading more about David Howell re Hikaru Nakamura, I kinda suspect 'draw by theory' means exactly 'quick draw'. And then 'fighting draw' just means any draw that isn't 'draw by theory'. Then again, I'm assuming 'theory' here refers to opening theory (instead of, say...endgame theory?)

However, I have read about situations where openings are analysed all the way to endgames, so I don't think draw by theory refers to just quick draw. Maybe draw by theory is a superset of quick draw.

# Answer
> 3 votes
You are right in the fact that the "draw by theory" refers to (mostly) the opening theory. One of the big criticisms of classical chess is that the starting position has been analyzed very extensively and a player has, if they so want, choices of opening theory that lead almost guaranteed to a draw (thus "draw by theory"). These lines often revolve around avoiding any chance of initiative and active play for the opposing side while sacrificing any chance on a win on your own side until a balanced endgame situation is reached. One could make the example that the French exchange variation (https://en.wikipedia.org/wiki/French\_Defence#Exchange\_Variation:\_3.exd5\_exd5) falls into this category.

On the other hand, chess960 offers too many starting positions to reliably memorize at least one such line for every starting positions. When presented with an unknown starting position, both players have to rely on their skill and understanding of the game (as opposed to memorization techniques) to get the most out of the game. While this might not result in a different draw rate at higher levels, it will result in what many people would describe as a more interesting game ("fighting draw").

# Answer
> 2 votes
This is more like an extended comment than an answer...

Actually, "draw by theory" can have two meanings.

First, it's what QueensKnight already described - the theory is very deep, all deviations have been handled and are no good for the deviator, and the end position is not much to play on, since there are no "imbalances". (For example, a position can be technically = if White is materially, but Black positionally better. Or think of the Berlin Wall, which is rock solid drawish, but surprising ideas like b5!! kept popping up, since we have the imbalance pawn structure vs. bishop pair.)

On the other hand, "draw by theory" can also mean well known variants which end up in a forced repetition of moves (e.g. remember the famous game Hamppe-Meitner? *That* one is busted by computers BTW...). If you are accused of that, effectively you are accused of cheating! (Fun fact: I was kiebitzing in a youth tournament. Two delinquents just ended their game which *was* Hamppe-Meitner. Me: *nudge nudge wink wink mode* "Oooh, Hamppe-Meitner!" They: *I didn't do anything mode* "Who???" They were sooo lucky I wasn't the arbiter...)

A very interesting post on draws, be them theoretic, cheated or fighted out.

---
Tags: chess-variants, terminology, chess960
---


title: What is the most complex chess problem?

text:
# Question
Title: What is the most complex chess problem?
There are many chess problems and studies that are very nuanced and can take ages to properly figure out.

What is the chess puzzle/problem with the longest (proven) solution?

# Answer
If you're looking for the puzzle with the longest forced sequence, it would be this position ,which contains a win for white in 549 moves.

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

```

It was found by computers from the generation of 7-man endgame tablebases, and there are several similar positions with the same distance to mate.

If that seems a little extreme, then the longest mate puzzle made by a human was Otto Blathy's 'monster', which is a mate in 292 moves but contains an illegal starting position (i.e. it could never occur in a real game).

If you won't accept that, then here are the current record-holders for the longest puzzles created by a person from legal positions - A mate in 271 with 'obtrusive units' (legal, but must have come about through piece promotion, such as having two dark-squared bishops) and a mate in 267 without those. And, surprisingly, both of those were created by the *same* person.

As for the "most variations that don't work" as you stated, it's probably also the mate in 549 listed above, with the number of moves that would let the other player slip out or otherwise prolong the sequence even more.
> 16 votes

# Answer
Most complex problem I know of:

```
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

```

White to move.
> 11 votes

# Answer
The above problem is computer generated. The most complex man made chess puzzle is by David Zimbeck at www.zimbeckchess.com the main lines are always at least 30 or so moves with endings that take another 50 or so(so about 80-100 moves in total). Its starts with almost a full set of pieces and finishes with 3 knights and a pawn vs a queen and reduces to 3 knights vs a king.

I should add the link with the "longest" man made puzzles are not necessarily the most complex. The 271 length record by Petrovic is not actually complex because the moves repeat. Similar puzzles of length can be found in "Jeremy Morse Tasks and Records". The Zimbeck study has its complexity because there is many complicated sidelines.

If it doesnt have to be purely man made then yes, as the op said the 549 move tablebase currently is obviously the most complex.

http://www.zimbeckchess.com/1.htm
> 6 votes

# Answer
For the purpose of this answer, I'll guess that JMcPherson is asking for that chess problem that stipulates "White to play and mate in *n*" for the greatest possible *n*. Direct-mate in *n*, in other words.

There are chess problems with stipulations other than "White to play and mate in *n*", but let's stick to direct-mates for this answer.

For the problem to be sound, there must be a unique key (first move for White), and, after that, Black must be able to play in such a way that White is forced to go the whole *n* moves and never has a choice of move at any turn. Such a choice for White is known as a dual. We thus need the problem to be dual-free.

The tablebase mate in 549 cited by DTR is not a sound #549 problem because White can play in such a way that, on *some* occasions in the long solution line, every Black response which is strong enough to force White to go the full 549. moves gives White a choice (either on White's very next move or later). The same goes for the mates in 271 and 267 DTR mentioned.

One problem which has been cited as the longest dual-free direct-mate is the following.

```
[Title "Walther Jørgensen, Thema Danicum 26, Apr 1982, no.1921"]
[fen "1N2Q3/p6n/p5n1/p1p2rpb/p4k1r/K1P4p/2PP4/6B1 w - - 0 1"]

1. Bh2+! Kf3 2. Qe3+ Kg2 3. Qg1+ Kf3 4. Qf1+ Kg4 5. Qe2+ Rf3 6. Qe6+ Rf5 7. Nd7 Kf3 8. Qe3+ Kg2 9. Qg1+ Kf3 10. Qf1+ Kg4 11. Qe2+ Rf3 12. Qe6+ Rf5 13. Kb2! Kf3 14. Qe3+ Kg2 15. Qg1+ Kf3 16. Qf1+ Kg4 17. Qe2+ Rf3 18. Qe6+ Rf5 19. Kc1! Kf3 20. Qe3+ Kg2 21. Qg1+ Kf3 22. Qf1+ Kg4 23. Qe2+ Rf3 24. Qe6+ Rf5 25. Kd1! a3! 26. Kc1 Kf3 27. Qe3+ Kg2 28. Qg1+ Kf3 29. Qf1+ Kg4 30. Qe2+ Rf3 31. Qe6+ Rf5 32. Kb1 Kf3 33. Qe3+ Kg2 34. Qg1+ Kf3 35. Qf1+ Kg4 36. Qe2+ Rf3 37. Qe6+ Rf5 38. Ka2 Kf3 39. Qe3+ Kg2 40. Qg1+ Kf3 41. Qf1+ Kg4 42. Qe2+ Rf3 43. Qe6+ Rf5 44. Kxa3 Kf3 45. Qe3+ Kg2 46. Qg1+ Kf3 47. Qf1+ Kg4 48. Qe2+ Rf3 49. Qe6+ Rf5 50. Kb2 Kf3 51. Qe3+ Kg2 52. Qg1+ Kf3 53. Qf1+ Kg4 54. Qe2+ Rf3 55. Qe6+ Rf5 56. Kc1 Kf3 57. Qe3+ Kg2 58. Qg1+ Kf3 59. Qf1+ Kg4 60. Qe2+ Rf3 61. Qe6+ Rf5 62. Kd1 a4! 63. Kc1 Kf3 64. Qe3+ Kg2 65. Qg1+ Kf3 66. Qf1+ Kg4 67. Qe2+ Rf3 68. Qe6+ Rf5 69. Kd1 a5! 70. Kc1 Kf3 71. Qe3+ Kg2 72. Qg1+ Kf3 73. Qf1+ Kg4 74. Qe2+ Rf3 75. Qe6+ Rf5 76. Kd1 a6! 77. Kc1 Kf3 78. Qe3+ Kg2 79. Qg1+ Kf3 80. Qf1+ Kg4 81. Qe2+ Rf3 82. Qe6+ Rf5 83. Kd1 a3 84. Kc1 Kf3 85. Qe3+ Kg2 86. Qg1+ Kf3 87. Qf1+ Kg4 88. Qe2+ Rf3 89. Qe6+ Rf5 90. Kb1 Kf3 91. Qe3+ Kg2 92. Qg1+ Kf3 93. Qf1+ Kg4 94. Qe2+ Rf3 95. Qe6+ Rf5 96. Ka2 Kf3 97. Qe3+ Kg2 98. Qg1+ Kf3 99. Qf1+ Kg4 100. Qe2+ Rf3 101. Qe6+ Rf5 102. Kxa3 Kf3 103. Qe3+ Kg2 104. Qg1+ Kf3 105. Qf1+ Kg4 106. Qe2+ Rf3 107. Qe6+ Rf5 108. Kb2 Kf3 109. Qe3+ Kg2 110. Qg1+ Kf3 111. Qf1+ Kg4 112. Qe2+ Rf3 113. Qe6+ Rf5 114. Kc1 Kf3 115. Qe3+ Kg2 116. Qg1+ Kf3 117. Qf1+ Kg4 118. Qe2+ Rf3 119. Qe6+ Rf5 120. Kd1 a4! 121. Kc1 Kf3 122. Qe3+ Kg2 123. Qg1+ Kf3 124. Qf1+ Kg4 125. Qe2+ Rf3 126. Qe6+ Rf5 127. Kd1 a5! 128. Kc1 Kf3 129. Qe3+ Kg2 130. Qg1+ Kf3 131. Qf1+ Kg4 132. Qe2+ Rf3 133. Qe6+ Rf5 134. Kd1 a3 135. Kc1 Kf3 136. Qe3+ Kg2 137. Qg1+ Kf3 138. Qf1+ Kg4 139. Qe2+ Rf3 140. Qe6+ Rf5 141. Kb1 Kf3 142. Qe3+ Kg2 143. Qg1+ Kf3 144. Qf1+ Kg4 145. Qe2+ Rf3 146. Qe6+ Rf5 147. Ka2 Kf3 148. Qe3+ Kg2 149. Qg1+ Kf3 150. Qf1+ Kg4 151. Qe2+ Rf3 152. Qe6+ Rf5 153. Kxa3 Kf3 154. Qe3+ Kg2 155. Qg1+ Kf3 156. Qf1+ Kg4 157. Qe2+ Rf3 158. Qe6+ Rf5 159. Kb2 Kf3 160. Qe3+ Kg2 161. Qg1+ Kf3 162. Qf1+ Kg4 163. Qe2+ Rf3 164. Qe6+ Rf5 165. Kc1 Kf3 166. Qe3+ Kg2 167. Qg1+ Kf3 168. Qf1+ Kg4 169. Qe2+ Rf3 170. Qe6+ Rf5 171. Kd1 a4 172. Kc1 Kf3 173. Qe3+ Kg2 174. Qg1+ Kf3 175. Qf1+ Kg4 176. Qe2+ Rf3 177. Qe6+ Rf5 178. Kd1 c4! 179. Kc1 Kf3 180. Qe3+ Kg2 181. Qg1+ Kf3 182. Qf1+ Ke4! 183. Qxc4+ Kf3 184. Qf1+ Kg4 185. Qe2+ Rf3 186. Qe6+ Rf5 187. Kd1 a3 188. Kc1 Kf3 189. Qe3+ Kg2 190. Qg1+ Kf3 191. Qf1+ Kg4 192. Qe2+ Rf3 193. Qe6+ Rf5 194. Kb1 Kf3 195. Qe3+ Kg2 196. Qg1+ Kf3 197. Qf1+ Kg4 198. Qe2+ Rf3 199. Qe6+ Rf5 200. Ka2 Kf3 201. Qe3+ Kg2 202. Qg1+ Kf3 203. Qf1+ Kg4 204. Qe2+ Rf3 205. Qe6+ Rf5 206. Kxa3 Kf3 207. Qe3+ Kg2 208. Qg1+ Kf3 209. Qf1+ Kg4 210. Qe2+ Rf3 211. Qe6+ Rf5 212. Kb2 Kf3 213. Qe3+ Kg2 214. Qg1+ Kf3 215. Qf1+ Kg4 216. Qe2+ Rf3 217. Qe6+ Rf5 218. Kc1 Kf3 219. Qe3+ Kg2 220. Qg1+ Kf3 221. Qf1+ Kg4 222. Qe2+ Rf3 223. Qe6+ Rf5 224. Kd1 Nf8,Nf6 225. Nf6+ Kf3 226. Qe2#

```

This problem is at PDB, from where I copied the moves. Morse lists it as the longest dual-free direct-mate; it is no. 741 in \[1\] and no. 865 in \[2\].

This problem is a 26-move extension of an earlier #200 by Jørgensen: Special Prize, *Die Schwalbe*, 1976. That problem is also at PDB, and is no. 740 in \[1\].

*Is* the #226 the record-holder? This web page at chessbase.com claims that the record-holder is a #203, which is Jørgensen's earlier #200 with a more modest 3-move extension by André Chéron. Now that chessbase.com web page is dated 2015. Has it cited information which is out-of-date? Or has the #226 been cooked? I don't know.

DTR cited a #292 by Otto Bláthy and correctly stated that its starting position is illegal. So to assess the above #226's acceptability, it is worth looking at its diagram to see if it is legal. It is, just. Four black pawns have made 8 captures b7xa6, c7xb6xa5, d7xc6xb5xa4, e7xd6xc5. White has 7 units, so those captures were of all but 1 of White's 9 missing units.

All those 8 captures were on the queenside, but White is missing all 4 kingside pawns. Black has 13 units, so White has made 3 captures. One was b2xc3, leaving 2. White could have also captured exd, but no more than 1 of White's kingside pawns can have made it to the queenside to be captured by a black pawn; no more than 1 was captured by a piece, so at least 2 had to promote.

It is just possible that only 2 White pawns promoted: the fP and gP. A piece captured White's hP. White's eP captured a piece on the d-file, then was captured by Black's eP on d7. White's gP captured Black's fP on the f-file, and White's fP and gP promoted on f8.

However, even if a problem's diagram cannot be reached without pawns promoting earlier in the game, that fact is not generally held against the problem, so long as it can be reached. What are regarded as blemishes are obtrusive pieces. Jørgensen's #226's diagram does not contain any obtrusive piece.

\[1\] Morse, Sir Jeremy. Chess Problems: Tasks & Records. 1st ed. Pub Faber & Faber, 1995. ISBN 0-571-15363-1

\[2\] Morse, Sir Jeremy. Chess Problems: Tasks & Records. 3rd ed. Pub Faber & Faber, 2016. ISBN 9781785891434
> 4 votes

# Answer
I know of a *very* complex selfmate with just 8 pieces on the board! I wouldn’t blame you if you couldn’t solve it yourself!

```
[Title "William Shinkman, 1907, Selfmate In 259 Moves"]
[FEN "8/8/8/8/QK6/1n6/B6R/r3k3 w - - 0 1"]

```

This position was originally published as a 423-mover initially, but then it was quickly changed to a 418-mover. It was then republished later on as a 298-mover after it was cooked by Joesph Babson and F.H. Curtiss. Nearly 80 years later, a further cook was found by Yaakov Mintz, and the 259 move solution was published in The Problemist 05/1985, on page 36.

Here is that solution.

```
[Title "Yaakov Mintz. After William Shinkman, 1985, Selfmate In 259 Moves"]
[FEN "8/8/8/8/QK6/1n6/B6R/r3k3 w - - 0 1"]

1. Qe8+ Kf1 2. Rh1+ Kf2 3. Qf7+ Kg2 4. Qd5+ Kg3 5. Qg5+ Kf3 6. Rh3+ Ke2 7. Qg4+ Kd2 8. Rh2+ Kc1 9. Qc4+ Kd1 10. Qc2+ Ke1 11. Qe4+ Kf1 12. Qf3+ Kg1 13. Qg3+ Kf1 14. Rh1+ Ke2 15. Qg2+ Ke3 16. Rh3+ Kf4 17. Rf3+ Ke5 18. Qg5+ Ke4 19. Qf4+ Kd5 20. Rd3+ Ke6 21. Rd6+ Ke7 22. Qf6+ Ke8 23. Re6+ Kd7 24. Qe7+ Kc8 25. Qe8+ Kc7 26. Rc6+ Kb7 27. Qd7+ Ka8 28. Ra6+ Kb8 29. Rb6+ Ka8 30. Qa4+ Na5 31. Ra6+ Kb8 32. Qe8+ Kb7 33. Qb5+ Kc8 34. Ra8+ Kc7 35. Qb8+ Kd7 36. Qd8+ Kc6 37. Ra6+ Kb7 38. Qb6+ Kc8 39. Ra8+ Kd7 40. Rd8+ Ke7 41. Qc7+ Kf6 42. Rf8+ Kg6 43. Qf7+ Kg5 44. Qf4+ Kg6 45. Rg8+ Kh5 46. Rh8+ Kg6 47. Qf7+ Kg5 48. Rh5+ Kg4 49. Qf5+ Kg3 50. Rh3+ Kg2 51. Bd5+ Kg1 52. Rg3+ Kh2 53. Rg2+ Kh1 54. Rg4+ Kh2 55. Qf4+ Kh3 56. Rg3+ Kh2 57. Re3+ Kg1 58. Qg3+ Kf1 59. Bg2+ Kg1 60. Bc6+ Kf1 61. Rf3+ Ke2 62. Qg2+ Ke1 63. Qg1+ Ke2 64. Rf2+ Ke3 65. Qg3+ Kd4 66. Qf4+ Kd3 67. Bb5+ Nc4 68. Qd2+ Ke4 69. Bc6+ Ke5 70. Qf4+ Ke6 71. Qf7+ Kd6 72. Qd7+ Ke5 73. Qg7+ Ke6 74. Rf6+ Ke5 75. Rf3+ Ke6 76. Qd7+ Ke5 77. Qe7+ Kd4 78. Qf6+ Ne5 79. Qh4+ Ng4 80. Qd8+ Ke5 81. Qg5+ Kd4 82. Qd2+ Ke5 83. Qf4+ Ke6 84. Qf5+ Kd6 85. Qc5+ Ke6 86. Bd5+ Ke5 87. Ba8+ Ke6 88. Qd5+ Ke7 89. Rf7+ Ke8 90. Qe6+ Kd8 91. Rd7+ Kc8 92. Bb7+ Kb8 93. Qe8+ Ka7 94. Be4+ Kb6 95. Rd6+ Kc7 96. Qc6+ Kb8 97. Qb6+ Kc8 98. Rc6+ Kd7 99. Bf5+ Ke8 100. Re6+ Kd7 101. Rf6+ Ke8 102. Qc6+ Ke7 103. Qd6+ Ke8 104. Re6+ Kf7 105. Qe7+ Kg8 106. Rg6+ Kh8 107. Qh4+ Nh6 108. Qd4+ Kh7 109. Rg7+ Kh8 110. Rb7+ Kg8 111. Bh7+ Kf8 112. Qh8+ Ng8 113. Qg7+ Ke8 114. Qg6+ Kd8 115. Qd6+ Kc8 116. Qc6+ Kd8 117. Rb8+ Ke7 118. Qc7+ Kf6 119. Rb6+ Kg5 120. Qg3+ Kh5 121. Qh3+ Kg5 122. Rg6+ Kf4 123. Qg3+ Kf5 124. Qg5+ Ke4 125. Rf6+ Kd4 126. Rf4+ Ke3 127. Qg3+ Kd2 128. Qc3+ Kd1 129. Qc2+ Ke1 130. Qf2+ Kd1 131. Qf1+ Kd2 132. Rf2+ Ke3 133. Re2+ Kd4 134. Re4+ Kd5 135. Qf7+ Kd6 136. Re6+ Kd5 137. Rb6+ Ke5 138. Qf5+ Kd4 139. Qf4+ Kd5 140. Be4+ Kd4 141. Bf3+ Kd3 142. Qe4+ Kd2 143. Qe2+ Kc1 144. Qe1+ Kb2 145. Qc3+ Ka2 146. Qa3+ Kb1 147. Kc5+ Kc2 148. Qb2+ Kd3 149. Qd4+ Kc2 150. Be4+ Kc1 151. Qg1+ Kd2 152. Rb2+ Kc3 153. Rc2+ Kb3 154. Qg3+ Ka4 155. Bc6+ Ka5 156. Qc7+ Ka6 157. Bb7+ Ka7 158. Qb6+ Kb8 159. Be4+ Kc8 160. Kd5+ Kd7 161. Qd6+ Ke8 162. Rc8+ Kf7 163. Qg6+ Ke7 164. Re8+ Kd7 165. Qe6+ Kc7 166. Qd6+ Kb7 167. Ke6+ Ka7 168. Qc5+ Ka6 169. Qc4+ Ka5 170. Ra8+ Kb6 171. Rb8+ Ka5 172. Rb5+ Ka6 173. Qc6+ Ka7 174. Rb7+ Ka8 175. Rh7+ Kb8 176. Qb6+ Kc8 177. Qb7+ Kd8 178. Qc7+ Ke8 179. Bc6+ Kf8 180. Qd6+ Ne7 181. Qb8+ Nc8 182. Rh8+ Kg7 183. Qb2+ Kg6 184. Be4+ Kg5 185. Qf6+ Kg4 186. Qf3+ Kg5 187. Qe3+ Kg4 188. Bf3+ Kg3 189. Bd5+ Kg4 190. Qf3+ Kg5 191. Rh5+ Kg6 192. Qf5+ Kg7 193. Qf6+ Kg8 194. Rg5+ Kh7 195. Rg7+ Kh8 196. Re7+ Kg8 197. Qf7+ Kh8 198. Qh5+ Kg8 199. Kd7+ Kf8 200. Rf7+ Kg8 201. Qg5+ Kh8 202. Rf8+ Kh7 203. Bg8+ Kh8 204. Bf7+ Kh7 205. Bg6+ Kg7 206. Qf6+ Kh6 207. Be8+ Kh7 208. Rf7+ Kg8 209. Qg5+ Kh8 210. Rf8+ Kh7 211. Qg8+ Kh6 212. Qh8+ Kg5 213. Qf6+ Kg4 214. Qf3+ Kh4 215. Qf2+ Kg5 216. Qe3+ Kh4 217. Rf4+ Kg5 218. Rc4+ Kf6 219. Qf3+ Ke5 220. Qe4+ Kf6 221. Qg6+ Ke5 222. Re4+ Kd5 223. Qe6+ Kc5 224. Rc4+ Kb5 225. Kd8+ Ka5 226. Rc5+ Kb4 227. Qc4+ Ka3 228. Ra5+ Kb2 229. Qb4+ Kc2 230. Rc5+ Kd3 231. Bb5+ Ke3232. Rc3+ Kd2 233. Qd4+ Ke1 234. Re3+ Kf2 235. Qd2+ Kg1 236. Rg3+ Kh1 237. Rh3+ Kg1 238. Qe3+ Kg2 239. Bc6+ Kf1 240. Rf3+ Kg2 241. Qd2+ Kh1 242. Rh3+ Kg1 243. Rg3+ Kf1 244. Bg2+ Kg1 245. Ba8+ Kf1 246. Rf3+ Kg1 247. Qf2+ Kh1 248. Rg3+ Rxa8 249. Qf1+ Kh2 250. Rg2+ Kh3 251. Qf3+ Kh4 252. Rh2+ Kg5 253. Rh5+ Kg6 254. Qg4+ Kf7 255. Rf5+ Ke6 256. Qe4+ Kd6 257. Qe5+ Kc6 258. Qb5+ Kd6 259. Qb6+ Nxb6#

```

Here is a Google Books link to my chosen source of an original publication (although it was also sent elsewhere by Shinkman), The British Chess Magazine Volume 27, See page 92, along with a Chess Problem Databse link.

In the 28th Volume, the 298-move cook was published on page 281.

The mentioned later republication of the problem but with the 298-move stipulation can be seen here, also on the Chess Problem Database. This is also where the 259-move solution, but with some changes in moves 5 to 10, in accordance to a comment left by Olaf Jenkner there.

Shinkman published a small bookelt in 1907 that explains the logic behind his selfmate, a PDF of which can be found here.

What a long problem for a position with just 8 pieces on the board!

Elsehwere
> 3 votes

# Answer
A certain similarity to @DTR's answer above which is mate in 1097 ply. This is mate in 1098 ply.

```
[Event "Black to play, mate in 1098 ply"]
[Site "?"]
[Date "2021.11.04"]
[Round "?"]
[White "martin"]
[Black "martin"]
[Result "*"]
[ECO "A00"]
[FEN "1n1k4/6Q1/5KP1/8/7Q/1r4b1/8/8 b - - 0 1"]
[startflipped ""]

1... Bxh4+{and_White_mates_in_549} (1... Rb6+ 2. Kf7+ Bxh4 (2...Kc8{c7} 3. Qxg3) 3. Qd4+ Kc7 4. g7 )
(1... Rf3+ 2. Ke6+ Bxh4 3. Qd4+ Ke8 4. g7 Rg3 (4... Rf6+ 5. Qxf6 Bxf6
6. g8=Q#)  (4... Nc6 5. Qd7#) 5. Qxh4 Rxg7 6. Qh8+ )  (1... Nd7+ 2.
Ke6+ Kc7 3. Qc4+ )

```

(In view of the threat 2.Qhh8# only the moves shown need be considered.)
> 1 votes

---
Tags: problems
---


title: Chess Annotation Software

text:
# Question
Title: Chess Annotation Software
I frequently use chess.com to self-analyze and annotate my games. Although it has a useful feature to save my annotated game as a url (which I then save as a bookmark), I'd rather switch to local software so that I may organize and backup my collection.

I have tried a couple of engine-oriented programs like Shredder and Stockfish for mac, but they don't really fit my needs.

I generally just need software where I can import a pgn (or setup a position), make moves on both sides of the board, add annotations, and add move variations. And that's pretty much it. It would also be nice to be able to categorize my games for easier access.

I don't need a chess engine or any computer-assisted analysis, although I understand that those would probably be bundled with most chess software.

Can anyone provide any suggestions that might fit all or some of this criteria? Any help would be appreciated!

# Answer
> 5 votes
Chessbase meets all your criteria and more. For example, it also allows you to look up any position in a reference database, see the main moves other people have analyzed, etc. The downside is the price, so if want a cheaper option you could look into Fritz - it should also meet your criteria, although the price is still relatively high.

Even if you don't want all these features now, they could be useful down the road. Almost all serious players use Chessbase because of its wide range of useful functions.

# Answer
> 4 votes
I agree with @InertialIgnorance Chessbase is very useful and good. I have also used chess database software which have the advantage of being free:

* Scid ("Shane's Chess Information Database") is a free and open source UNIX, Windows, Linux, and Mac application for viewing and maintaining huge databases of chess games
* Scidb, is a free chess database application for Linux/Unix and Windows. Scidb is inspired by Scid but it is a completely new development.

# Answer
> 1 votes
nocheto.sallyx.org is probably the best for what you are looking for, but it works only under Linux. And its not free (although cheap for what it does).

---
Tags: software, annotation
---


# Question
Title: Are all female grandmasters alive (as of the date of this post, 2021Sep01)?
Really female GMs and not WGMs. I notice here there's a 'deceased' list for female IMs but none for female GMs.

Is it really the case that there are only 38 females awarded GM title in history and they're all alive today?

For both the list and even the list on FIDE, what I'm not quite seeing is a death date column with N/A for living players, so either they are lists for living female GMs or yes to what I asked.

# Answer
> 2 votes
Yes.

> With Lei securing her victory on Saturday, the biggest story of the day was Paehtz reaching her third GM norm. She had earlier norms from 2011 and 2016, which still need to be checked before it's certain that she will meet the requirements for the GM title. Chess.com has learned that there might be an issue with one of the norms, so perhaps the cheering for Paehtz was premature, but let's hope not.
>
> **If she does get the title, Paehtz will be only the 40th female player in history to achieve this (and all happen to be still alive)**. She had missed her chances for a norm in rounds nine and 10, but on Sunday she pulled it off with a win against IM Bibisara Assaubayeva.

# Answer
> 3 votes
**Update**: Ah, see the list of all grandmasters. This has a death date column. Click on sex to get all the F's together and then see they're alive.

---

Wait wiki page for Zhansaya Abdumalik, the most recent female grandmaster and the most recent grandmaster, says (but it's unsourced)

> She is the first Kazkakhstani woman, and the 38th woman overall, to earn the GM title.

So I guess they're all still alive since there are 38 female grandmasters in this list (i.e. this list is all female grandmasters and not just all living female grandmasters and thus all female grandmasters = all living female grandmasters). Then again the quote is unsourced.

---
Tags: history, statistics, grandmaster, women
---


# Question
Title: Daily game -- Is my opponent playing honestly?
At chess.com, my daily rating is 1500+ (my puzzle rating: 2400+; my blitz rating: 1600+ and my rapid rating: 1700+) and I played two games with the same opponent whose daily rating is much lower than mine (his daily rating: 1200+; his puzzle rating: 2000+; blitz rating: 1300+; rapid rating: 1500+). I was not only defeated in both games, but I also did not even have any chance of winning or even drawing. Of course, the accuracy of all his moves is not 100%, but I can hardly imagine me standing no chance playing against a player whose rating is a few hundreds below me. I suspect he made some moves by himself, but also received help, either from a much stronger player, or from some engine at least several times during each game. However, I have no black-and-white evidence supporting my suspicion.

Here is the first game (I play black):

```
    8/4k1p1/4p2p/1pp1B3/2p5/P1P5/5P1P/6K1 b - - 2 30
   1. d4 d5 2. c4 c6 3. Nc3 Nf6 4. Bg5 dxc4 5. Nf3 b5 6. a3 Bb7 7. e4 Nbd7 8. Be2
h6 9. Be3 e6 10. Ne5 Bd6 11. Nxf7  Kxf7 12. e5 Nxe5 13. dxe5 Bxe5
14. Qc2 Bxc3+ 15. bxc3 Qd5 16. O-O Rad8 17. Rad1 Qe4 18. Qb2 Rd7 19. Bf3 Qf5 20. Bxa7 Rhd8 21. Rxd7+  Rxd7 22. Bb8 Ne4  23. Re1 Rd2 24. Qc1 c5 25. Rxe4 Bxe4 26. Qxd2 Bxf3 27. gxf3 Qxf3 28. Qf4+ Qxf4 29. Bxf4 Ke7 30. Be5 1-0

```

I was really impressed by his key move 24. Qc1. It was hard for me to imagine a 1200+ player can find such a surprisingly good move. I have a coach who is rated 2200+ and he did not see this move when he was analysing this position.

Here is the second game (I play white):

```
5rk1/7p/1pRp2p1/p2Pb3/3pP2q/P2Q2PP/1P4BK/8 b - - 3 25
1. e4 c5 2. c4 Nc6 3. Nc3 g6 4. g3 Bg7 5. Nge2 Nf6 6. Bg2 e5 7. O-O O-O 8. d3 d6
9. Rb1 a5 10. a3 Be6 11. h3 Qd7 12. Kh2 Nh5 13. f4 f5 14. Be3 Nd4 15. Bxd4 cxd4
16. Nd5 fxe4 17. dxe4 Bxd5 18. cxd5 exf4 19. Nxf4 Nxf4 20. Rxf4 Qe7 21. Qd2 b6
22. Rc1 Be5 23. Rxf8+ Rxf8 24. Rc6 Qh4

```

Here black has a clearly winning position. I feel completely overwhelmed in this entire game. Again, I do not understand why a 1200+ player can play so well.

So my question is, did my 1200+ rated opponent play honestly in these two games, or is it likely he cheated by receiving external help?

# Answer
> 4 votes
I have no way of knowing for sure whether your opponent cheated - however, I suspect he did not.

In the first game, Qc1 could easily have been luck. Keep in mind that your opponent isn't choosing from dozens of possible moves here. The queen is threatened and it only has a few reasonable squares to move to; I could see him choosing that square for his queen even if he didn't see the follow-up at that time (and I don't think it's totally unreasonable, especially in a correspondence game where you can legally take notes and play out the position on another board, that he *could* see the follow-up.)

As for the second game... Well. Out of 24 moves, the chess.com analysis says Black made 2 blunders, 3 mistakes, and 2 inaccuracies. That's pretty much a third of the moves after the book moves. In contrast, he only played a "excellent" or better 8 times. That really doesn't look like cheating to me. (Not that you can't cleverly play "blunders" when you're winning that leave the game solidly in your hands - but he didn't even do that; the first blunder, according to the analysis, took the evaluation from -1.56 to +0.61, which seems like an odd thing to allow if you're cheating.)

---
Tags: online-chess, correspondence-chess, cheating
---


# Question
Title: Is it possible for White to win in this rook and knight endgame?
In a game I recently played, I was playing White and I blundered quite a bit to reach this position.

```
[FEN "8/R1N4p/2k5/1pn1K3/8/3r4/P4r2/8 w - - 0 1"]

```

Is it possible for White to win at all? I had four minutes at hand, and I sat down thinking about all the possible moves I could make by giving the Black king constant checks to win. However, I could not think of anything here.

# Answer
No matter what, White is doomed. Black has much more material and there is no immediate threat to the Black king that White can cook up. The only checks available are futile ones. Additionally, the White king is in the hole, deep into a mating net and constricted by two Black rooks. Checkmate is inevitable in this position.

In fact, according to Stockfish analysis, Black has a mate in 7 here with White's best play.

```
[FEN "8/R1N4p/2k5/1pn1K3/8/3r4/P4r2/8 w - - 0 1"]

1. Ra3 Rxa3 2. Nd5 Re2+ 3. Kf6 Re6+ 4. Kf7 Kxd5 5. Kg7 Ra7+ 6. Kf8 Rb6 7. Ke8 Rb8#

```
> 7 votes

# Answer
Pretty hopeless unless your opponent blunders. Your only strategy is to avoid rook trades and use your knight to set up a fork. Unfortunately, you have no immediate move that proceeds with this strategy. If your rook moves, you well lose your knight. Your king has no legal moves. And if you move your night then Rd5 is mate. Your only hope is to play Na6, in the hope that your opponent misses mate in 1!
> 3 votes

# Answer
Black mates in 3 moves. White king is already in check and king has only one legal move that is Ke5 So 1.Ke5 Re3+ again king has only one legal move i.e. Kd4. 2.Kd4 Re4+ again king has only one legal move i.e. Kc3 3.Kc3 b4#.
> 0 votes

---
Tags: endgame, blunder, rook-and-minor-endgame
---


# Question
Title: Move generation for sliding pieces and Hyperbola Quintessence
I'm working on a bitboard-based chess engine at the moment and I have managed to generate pseudo-legal moves for knights, kings and pawns. However, I'm still trying to wrap my head around sliding pieces (bishops, rooks, queens). I have come across this algorithm which approaches the problem, with the "o^(o - 2r) trick", but I found it overall quite confusing. I have tried implementing it for files in the following function but it doesn't seem to work:

```
uint64_t compute_pseudo_file(uint64_t pieceBB[], uint64_t sliderBB, uint64_t own_side) {
  // o^(o - 2r)
  int sq = get_square(sliderBB);

  uint64_t occ = get_all_pieces(pieceBB) & get_file_mask(sq);

  uint64_t normal = occ - 2 * sliderBB;
  uint64_t reverse = _byteswap_uint64(occ) - 2 * _byteswap_uint64(sliderBB);

  return normal ^ reverse;
}

```

In this case, the `sliderBB` is:

```
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0

```

And the `occ` is:

```
0 0 0 1 0 0 0 0
0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 1 0 0 0 0
0 0 0 1 0 0 0 0

```

And the function `compute_pseudo_files()` returns this:

```
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
1 1 1 1 0 0 0 0
0 0 0 0 1 1 1 1
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0

```

When I'm expecting this:

```
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 1 0 0 0 0
0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0

```

I'm just getting into bitboards and bitwise manipulation now, so I'm clearly unfamiliar with a lot of stuff. I would appreciate any advice from anyone who has experience with these implementations and specifically on how to implement this algorithm for generating pseudo-legal moves for sliding pieces. I also think that this post would be helpful for others who are getting into chess engines and bitboards.

# Answer
> 2 votes
Your implementation looks incorrect to me. Here's the correct hyperbola quintessence implementation:

```
Bitboard hyp_quint(Square square, Bitboard occ, Bitboard mask) {
    return (((mask & occ) - SQUARE_BB[square] * 2) ^
        reverse(reverse(mask & occ) - reverse(SQUARE_BB[square]) * 2)) & mask;
}

```
* `mask` is the file/rank/NW-SE diagonal/NE-SW diagonal mask, depending on the sliding piece
* `occ` is the *unmasked* occupied bitboard, equivalent to `get_all_pieces(pieceBB)` in the OP
* `SQUARE_BB[square]` is a bitboard with a single set bit at the position of the sliding piece, equivalent to `sliderBB` in the OP
* The `reverse` function can be implemented as follows:

```
Bitboard reverse(Bitboard b) {
    b = (b & 0x5555555555555555) << 1 | ((b >> 1) & 0x5555555555555555);
    b = (b & 0x3333333333333333) << 2 | ((b >> 2) & 0x3333333333333333);
    b = (b & 0x0f0f0f0f0f0f0f0f) << 4 | ((b >> 4) & 0x0f0f0f0f0f0f0f0f);
    b = (b & 0x00ff00ff00ff00ff) << 8 | ((b >> 8) & 0x00ff00ff00ff00ff);

    return (b << 48) | ((b & 0xffff0000) << 16) | ((b >> 16) & 0xffff0000) | (b >> 48);
}

```

So now if you want to generate sliding moves for a rook, you must call

```
Bitboard get_rook_attacks(Square square, Bitboard occ) {
    return hyp_quint(square, occ, MASK_FILE[file_of(square)]) |
           hyp_quint(square, occ, MASK_RANK[rank_of(square)]);
}

```

---
Tags: engines, computer-chess, bitboard
---


# Question
Title: Knights necessary to mate king on large finite board
How many knights would be necessary to mate opponent's king on large finite boards, like a **billion times a billion squares**?

Are they fast enough to surround the opponent's king in a **constant** number of times for various finite board sizes, or would you need some **f(board size)** of them, let's say millions for our board? Would there be a difference if attacking side could use it's king too?

It's not clear how geometry works here, but it looks like when the king starts running, it's pretty fast and only two knights are fast enough to follow it. On the other hand, knights can build setups giving additional time for some distant colleague to join slowly. We start with king in the center and knights in one corner and 50 moves rule doesn't apply...

# Answer
Not rigerous, however:

1. In lateral movement two knights move as fast as one king.
2. We know from end-game theory that two knights are not able to force the king into positions.

.. thus I'd say it's very unlikely that unlimited knights+king would be able to mate a king that has a free direction to run in (unlimited board). If it's possible to corner it however (limited board and unlimited moves), unlimited knights are certainly enough, as they could simply divide up the board and slowly decrease the available space.
> 4 votes

# Answer
I think we can at least set a maximum for the number of knights needed.

First off, the special cases. Checkmate is impossible on a 3x3 (or smaller) board. The knights cannot control the middle square and can thus never give checkmate. On a 4x4 board, the board is so small that if there are 4 knights and the king starts in the middle, the king is next to one of the knights and may be able to take it immediately and fork the remaining 3 for an easy draw, or if you move the king to the corner so it doesn't start in check, it starts the game immediately stalemated.

In the following diagram, the black pawns represent squares that the king cannot cross:

```
[FEN "3k4/8/8/ppp2ppp/2pppp2/NN4NN/8/8 w - - 0 1"]

```

If you imagine that pattern continuing, each pair of knights is controlling 6 files. So, to make a wall covering the entire board, you would need 2 knights for every 6 files. An additional 2 knights could ensure that the wall can slowly advance with no gaps. The wall can continue to advance until the opposing king is pinned to the back rank, and after that checkmate should be easy. So, on an NxN board of size at least 5, a maximum of `ceiling(N/6) * 2 + 2` knights should be enough to checkmate. On a 300x300 board, which contains 90,000 squares, 102 knights would therefore be sufficient. (This implies a maximum of 6 knights needed on a regulation 8x8 board, which I'm pretty sure is more than what is actually needed - 4 seems like it would be enough.)

There are probably better methods which could reduce this number, but I give it as a starting point.

> Are they fast enough to surround opponent's king in very limited **constant** count for various finite board sizes

It could never be constant (and that part won't change even if the side with the knights also has a king.) After all, only 2 knights (or a king) can chase the king, and 2 knights (or a king... or even 2 knights *and* a king) cannot force checkmate, so at the very least the opposing king could run until it hit the edge of the board, and the amount of moves that takes is a function of the board size. Therefore, no checkmating method could be faster than O(N). The method I give of advancing a wall seems to be O(N^2) since the wall has further to go and takes longer to advance the bigger the board is.
> 4 votes

# Answer
\[Not exactly an answer, but just to address the related question of an infinite board that was brought up by some answers and comments.\]

Here is a proper proof that it is impossible on an infinite board, even if only the right side of the board is infinite. Assign each piece a distance that is simply the column number. Let the (opponent) king start with distance k at least 3 more than the distance of any knight. We maintain the invariant that (k−1)·2 \> m+n where m,n are the two greatest distances of the knights (with m = n if there are two knights at the greatest distance). Observe that each knight move adds at most 2 to m+n. Also, if the invariant holds then there cannot be two knights that can attack the column just on the right of the king, so the king can clearly move to an unattacked square while moving rightward, preserving the invariant. Since the king can continue indefinitely, it is impossible to checkmate the king.
> 1 votes

---
Tags: checkmate, puzzles, knights, mathematics
---


title: Is this selfmate solvable or fixable?

text:
# Question
Title: Is this selfmate solvable or fixable?
This is a kind of a repost of a fascinating chess problem that appeared yesterday. The original poster got shy or something, and bafflingly deleted his own post, which was beginning to attract some good reputation and interest.

In the mean time, I have found some information which I want to share. So I will pose the question and then give one answer. Feel free to improve!

So: background. It seems that someone showed the original poster a problem a year ago, but the poster couldn't solve it, and wasn't quite sure if there was a solution at all. The problem is a selfmate: White to move has to coerce an unwilling Black into checkmating him. The poster didn't know how many moves it would take. Normally selfmates do have a specific move limit: they aren't like studies.

```
[Title "White to move and selfmate"]
[fen "kbQ5/pb6/P7/3B4/8/7p/7p/7K w - - 0 0"]

```

Is there a solution? If there is, what is it? And if there isn't, is the problem fixable?

# Answer
> 10 votes
First the verdict on the posted problem. It has certainly no solution in up to 12 moves (checked by Popeye v4.79). And the author of the Gustav software which specializes in selfmates says that there is probably no regular solution to this problem.

Another expert thinks that if White simply captures everything which moves, he can then push bK over to g3 and force Black to win by h3xg2#. That's like taking a long chess problem and solving it like an regular chess game with no limit to the number of moves. Yes it will work to win but it's not really in the spirit of things. That's not to diminish his ingenious approach, but it's just not what we would consider a solution.

The good news is that this problem turns out to be a recognizable example of the Broecker schema, invented in 1891 by Gustav Von Broecker. The German PDB database contains 36(!) other problems which are all based on the same diagonal opposition of bishops. One early very clear example is the following:

```

    [Title "Broecker - London Chess Fortnightly 1892 - s#9"]
    [fen "kb4R1/1b6/P7/8/8/7p/6BP/6BK w - - 0 0"]

    1. Rf8 Bc6 2. Re8 Bd5 3. Rd8 Be4 4. Rc8 Bf3 5. Rh8 Be4 6. Bf3 Bd5 7. Be4 Bc6 8. Bd5 Bb7 9. Bc6 Bxc6#

```

"s#9" is shorthand for "selfmate in 9" - i.e. White moves first and forces an uncooperative Black to checkmate White by Black's 9th move at the latest.

As the original poster had deduced, there is a key relationship between the square of the queen (or rook) on the 8th rank, with the number of squares separating the bishops. Either player must always make them match if they can, and if he fails to, the other player gets a chance to make them match instead.

White wins because he is able to match by moving 1. Tf8 only. Black has many possible lines of play, but the longest he can hold out is 9 moves. One example solution is shown here.

In the original problem, the position is already a "match" with White to play. He is forced to break the match, and Black can always recreate it, so need never lose. It doesn't seem there is any way for White to use the additional power of the queen to change the parity.

However the matrix has proved very rich over the years, as you can see from the database, and I am sure there's more that can still be mined. The longest problem known to be sound is the following:

```

    [Title "Rotenburg & Trillon - Die Schwalbe 1980 - s#14"]
    [fen "k7/1b4R1/N7/7p/8/7p/6BP/6BK w - - 0 0"]

    1. Rf7! Bc6 2. Re7 Bd5 3. Rd7 Be4 4. Rc7 Bf3 5. Rh7 Be4 6. Bf3 Bd5 7. Be4 Bc6 8. Bd5 Bb7 9. Bc6 h4! 10. Bd5 Bc6 11. Rc7 Bb7 12. Rc1 Bc6 13. Rb1 Bb7 14. Bc6 Bxc6#

```

Again, here is a sample solution as Black has multiple choices, although White's move is unique at every point.

What's interesting about this one is that Black has a waiting move. This flips the parity, and so normally Black would be able to continue making matches, while White is breaking matches. However, White can flip the parity, by moving to the other side of the main diagonal. This can only be done while ensuring that b7 is never free for bK to enter. Either it must be occupied by bB, or attacked by wR.

# Answer
> 5 votes
> Is there a solution?

I don't think so. If the White queen goes to a square where it can interpose, then Black can just play BxB.

If, for example, White tries Qe8-d7 or Qe8-e6, hoping Black will move his b8 bishop and allow Qc8+, Black can simply *not* move the b8 bishop. He could instead just move his light-squared bishop next to White's (White's queen cannot go from d7 or e6 to h8 to take advantage.)

```
[FEN "kbQ5/pb6/P7/3B4/8/7p/7p/7K w - - 0 1"]

1. Bf3 Bd5 2. Qe8 Bb7 3. Qd7 Be4 (3... Bf4? 4. Qc8+! Bb8 5. Bd5 Bc6 6. Qh8 Bb7 7. Bc6 Bxc6#) 4. Qc8 Bd5

```

If White does not do that, then I think Black can just use the following plan:

If Qg8, then Black moves bishops 0 apart (that is, BxB.).
If Qh8, then Black moves bishops 1 apart.
If Qc8, then Black moves bishops 2 apart.
If Qd8, then Black moves bishops 3 apart.
If Qe8, then Black moves bishops 4 apart.
If Qf8, then Black moves bishops 5 apart.
If at any time it is not possible to move the bishops like that, then BxB at that moment should force the queen to interpose.

> And if there isn't, is the problem fixable?

The problem has a solution if White's queen or bishop start on another square. For example, starting the queen on d7 or g8 would provide lots of places for the queen to go, but only one is correct.

Another possibility is to add a white pawn on a4; moving the pawn loses a tempo and allows White to win. (Although that's not a satisfying way to construct the problem, since it has more than one solution; White could play either a4 or Qh8 as the first move.)

# Answer
> 3 votes
\[Edit: *D M* found an error in my solution. The key reductions are correct but I missed a branch for Black (`9. .. Be4`) that evades all of those reductions.\]

I think I found the solution (16 moves on each side):

```
[Title "White Self-mate"]
[FEN "kbQ5/pb6/P7/3B4/8/7p/7p/7K w - - 0 1"]

1. Be4 Bc6 ( 1... Bd5? 2. Qh8 Bc6 3. Bd5 Bb7 4. Bc6 Bxc6#) 2. Bf3 Bd5 3. Bg2 Be4 4. Qd8 Bd5 (4... Bc6? 5. Bf3 Bb7 (5... Bd5 6. Qc8 Bc6 7. Be4 Bb7 8. Bd5) 6. Be4 Bc6 7. Qc8 Bb7 8. Bd5 Bc6 9. Qh8 Bb7 10. Bc6 Bxc6#) 5. Be4 Bb7 (5... Bc6 6. Qc8) 6. Bf3 Bc6 7. Bg2 Bd5 8. Qe8 Bc6 (8... Bb7 9. Bf3 Bc6 10. Qd8) 9. Qc8 Bd5 10. Qd8 Bc6 11. Bf3 Bb7 12. Be4 Bc6 13. Qc8 Bb7 14. Bd5 Bc6 15. Qh8 Bb7 16. Bc6 Bxc6#

```

We look at the pair (q,b) where q is the position of the queen in the 6 possible squares at the top row (1 to 6) and d is the distance between the bishops (1 to 5), after White's turn. The key reductions are:

1. If (q,b) = (6,1) then done.
2. If (q,b) = (1,2) then done.
3. If (q,b) = (2,3) then done.

These are (partially) shown in the first few two branches off the main line. Each reduction in the list can be proven based on the correctness of the preceding reductions. Based on these reductions, we can derive the entire solution. (From move 6 onwards I omit branches admitting a 1-move response that falls under these reductions.)

# Answer
> 2 votes
I may be missing something, but it seems that white needs their bishop to be on c6 and their queen to be on h8. If one of these is accomplished by changing the setup of the problem, then the other can be accomplished through white's move.

# Answer
> 1 votes
As for fixable ... that rather depends on what the presumed composer wanted to do. Or what history this particular problem had and what possible mistranscriptions it may have passed through during transmission. In extreme cases, it might be a 'place a white piece on the board to make this a self-mate in 5' type of problem that isn't correctly remembered. Or perhaps even a problem solving contest problem that is deliberately incorrect, but with many tries (i.e. moves that would be solutions if it wasn't for just one single move by black that upsets white's idea) that may fool competing solvers.

There are several tries (in 3, 4 or 5 moves) that involve the Bishop on d5. Moving it to e4 makes it a self-mate in 3, at least as far as having a solution is concerned. But it looks as that makes the pawn on h3 without a job, so it is probably necessary to figure out why the composer wanted to have that.

But, as D M already has indicated, replacing the white Queen also does the job, although I would consider it more likely that the position of the Queen is correctly remembered (assuming a mistranscription) -- but that pawn on h3 still seems bothersome ... ?

---
Tags: problems, zugzwang, selfmate, opposition
---


# Question
Title: Making my own chess engine for a college project
I'm starting my college project to build my own chess engine. The problem is that I have no clue where to start or what to read. I found videos on YouTube but I don't want to be a copycat. I want to build it on my own. What should I read and how can I build it? Is there any chance that I can make it with my own ideas?

# Answer
If your main goal is the engine, you can get the basic functionality following this kind of guide (i.e. https://andreasstckl.medium.com/writing-a-chess-program-in-one-day-30daff4610ec). With this, you can develop the basics (that guide is in python, but you can follow along with other languages): board painting, piece managing... (things that may be out of scope for your interests: the engine).

For creating a basic engine, you could start with this site: https://www.chessprogramming.org/Main\_Page, in which you will have content to create your engine (you'll get the concepts, not the code itself), like the simplified evaluation: https://www.chessprogramming.org/Simplified\_Evaluation\_Function

With those concepts, you can enrich your engine as you go by.

Hope this helps!
> 17 votes

# Answer
The number 1 goal is to make an engine that makes a *legal* move. The immediate next goal is to make an engine that calculates all legal moves - you can choose one at random.

Next up is an evaluator - how good is a position? Again, we can start with a low goal - just consider checkmate to be the ultimate score, and count the pieces if the position is not checkmate. We can always improve the evaluation function, but you need one to get started.
> 30 votes

# Answer
I think it has to be stated: you should start low.

First of all, as we are interested in a chess *engine* you should not spend effort creating a user interface (not even a crude one). You sbould make your engine speak either Chess Engine Communication Protocol or UCI. This way a number of existing graphical boards can be used with your engine, and lets you focus on the actual engine. This is exactly what is done by other engines such as Stockfish. And speaking the standard language for chess engines allows you run your program tests with other existing engines, to match against other programs, etc.

Second, your program will have to use some kind of internal representation of the game state. This will be basically the state of the board *plus some additional flags* (is castling allowed? An *en-passant* is possible?) Forsyth-Edwards Notation shows what you have to take into account. You could operate directly on FEN strings, but internally you may use any representation you want. You will need to translate between FEN and your internal structures.

Third, you will need to determine the moves you have available, as noted by MSalters. Initially make it pick a move at random.

At this point, *you have a Minimum viable product*. You have made your own chess engine. It plays quite badly, but you made an engine. From this point on, you could run out of time with your college project and still provide a working project.

Then the actual task is "just" making your engine *play well*, which is where things become really complex. You can build on existing algorithms, implement your own ideas and heuristics, etc.
> 6 votes

# Answer
Others have mentioned www.chessprogramming.org, but it does not seem to give a good explanation of negamax with alpha-beta pruning. You really need to understand this, as it is the key ingredient in getting an efficient chess engine. The static evaluation function is still important but much less than alpha-beta pruning and move-ordering heuristics and other pruning heuristics, as briefly mentioned in this related post. That is, if you replace the static evaluation function just by a checkmate checker plus a material balance evaluator, you would lose only a few moves of effective depth (i.e. you would need to search a few moves deeper to do as well as a better evaluation function that takes a small constant times as long to run). But if you remove alpha-beta pruning, your effective depth would be reduced by a significant fraction (possibly up to half)! And the move-ordering heuristics used with alpha-beta pruning as well as other pruning techniques would in general multiply the effective depth, hence improving them is very important!
> 4 votes

# Answer
I would recommend this video by Sebastian Lague. It will not give you all the answers, probably, but it summarizes a process of how he himself tried making an engine from scratch and what he learned along the way.
> 3 votes

---
Tags: engines, learning
---


# Question
Title: Is endangering the king a good strategy in some positions?
According to Wikipedia, "any chess piece except the king may be sacrificed". However, I am wondering,if in some rare situations, whether endangering the king can also be a good strategy. Here is what I mean.

In a position, I make a move after which my opponent has a checkmate in one. But this checkmate is very counterintuitive and is difficult to find, especially if my opponent is not so strong and/or they are in time trouble. If they miss this checkmate, my position is actually better.

Are there any examples of the above-mentioned scenario? Can endangering the king be a good idea occasionally, or should it always be avoided?

# Answer
> 26 votes
Whereas "sacrifice" is a bad word, as already was pointed out ("endangering" maybe), from the standpoint of game theory this strategy may be completely rational...if the players are fallible.

I abstract your example a bit. Assume the position is already at a -3 value with objective play value, i.e. it is lost. You have moves A and B. All opponent moves on A give a -3 position. On B the opponent can mate immediately (-infinity) or blunder away (0). The minimax value thus is -3, and a computer plays A since -infinity\<-3. With "hope chess" you play B - you don't have to lose anything since you will "normally" lose anyway. But since you wanted a position:

```
[FEN "2k5/2b5/N1KPN3/8/7B/8/8/8 b - - 0 1"]
[startflipped ""]

```

Black to move. "Best" is 1...Bxd6, and White only has to mate with BNN, not that hard. But why not shorten the torture by 1...Bd8? Maybe White is a patzer and triumphantly captures the B...stalemate.

# Answer
> 9 votes
What checkmate in 1 might be tricky to spot? One possibility: promoting a pawn to a knight. This might work better online than over the board: the software your opponent uses might make it easier to promote to queen than to another piece, and indeed some players have "auto-queen" turned on.

# Answer
> 4 votes
A maxim in chess is not to play a move while thinking "I hope he doesn't see it". This doesn't mean that your opponent will always spot the threat - and if they don't then congratulations on the easy win - but the point is that if opponent spots the threat, your move should still improve your position in some way.

Example:

```
[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nd4? 4. Nxe5?? Qg5 {Black wins material thanks to the dual threats of 5...Qxe5 and 5...Qxg2 6. Rf1 Qxe4+ 7. Be2 Nf3# if White rescues the knight with 5. Nxf7.}

```

So 3...Nd4 wins material if opponent doesn't see the threat. It's still not a good move however, because if it's parried (4. Nxd4 or 4. O-O) White gets a strong advantage.

You are describing something even worse than a simple bad move, since the consequence of opponent seeing it is you lose the game. Now if you are going to lose the game anyway, then it's a reasonable gambit to try, but in all other situations you should never intentionally make a move that can lose your the game if your opponent spots the refutation.

# Answer
> 4 votes
## Yes!

It is absolutely a valid strategy in online play with fast time controls. Here (youtube link) is an example in online play between two international masters:

```
[FEN "K/8/1R/8/8/5k/8/4qqqq w - - 0 1"]

1. Ka7 Qxb6 2. Ka8 Qef2?

```

After Qxb6, White has two moves, to take the queen which is mate in 3, or move to the corner which is mate in one. In the game, White played into the corner, which black did not expect, leading black to blunder stalemate before realizing what had happened.

# Answer
> 1 votes
Further to existing answers, another sort of checkmate in 1 that might be tricky to spot is checkmate by discovered check.

---
Tags: strategy, kings, king-safety
---


# Question
Title: Why is Magnus Carlsen's Elo rating not higher, given that his win rate is so high?
Magnus Carlsen's Elo rating is about 2870, and according to this quora answer, he hasn't lost a game in 100 games at the time of writing. Assuming that his win rate hasn't changed since then, and assuming this implies conservatively a win rate of 99%, then based on this table, which says that a 99% win rate against a single other player corresponds to about 670 ELO surplus, this seems to suggest that Magnus Carlsen plays players who have on average an Elo rating of 2200. Is this correct? it seems like it is way too low, given that my understanding is that the super grandmasters mostly play each other and other high-scoring grandmasters, at least in long games.

# Answer
> 24 votes
A 99% win rate is winning 99% of games played. Carlsen does not win nearly that many games, since at top level most games are drawn.

Carlsen's overall record in life is +1262 =1289 -454, which means 1262 wins, 1289 draws, 454 losses. He has won 42.00% of all the games he's been recorded to have played, and has an all-time average score of 63.44% (wins are 1 point, draws are 0.5 points, losses are 0 points).

Another thing is the amount of rating gained or lost depends on how strong your opponent is. If Carlsen were to play a beginner a hundred times, he'd win effortlessly for a 100% win rate - but he'd also gain almost no rating.

# Answer
> 16 votes
> assuming this implies conservatively a win rate of 99%

There are a number of wrong assumptions in your question. First, at elite levels where players don't often lose it is draw rates that are high. Second, according to the FIDE rating rules if the rating difference were 670 it would be adjusted down to 400:

> 8.54
>
> A difference in rating of more than 400 points shall be counted for rating purposes as though it were a difference of 400 points.

In fact over the last two years according to the data on FIDE's rating website for Carlsen he has won 40.7%, drawn 54.3% and lost 5% of his games.

Here are his results from November 2019 to date.

A "\*" next to the average rating shows that some or all of his opponents were rated more than 400 points lower than him and their ratings were adjusted up to give him more rating points.

| Date | Results | Rating Change | Avg. opponents' ratings | Event |
| --- | --- | --- | --- | --- |
| October 2021 | +4=5-1 | -0.2 | 2741 | Norway Chess 2021 |
| October 2021 | +2=1-0 | +0.3 | 2557\* | 36th European Chess Club Cup 2021 |
| September 2021 | +8=6-0 | +8.4 | 2672 | World Cup 2021 |
| March 2021 | +3=9-1 | -15.3 | 2714 | Tata Steel Masters 2021 |
| November 2020 | +5=3-2 | -0.8 | 2743 | Altibox Norway Chess 2020 |
| April 2020 | +1=0-0 | +0.8 | 2462\* | Ostlandsserien 2. div A 2019-2020 R 9-11 |
| February 2020 | +3=10-0 | -9.6 | 2731 | Tata Steel Masters 2020 |
| January 2020 | +1=3-0 | -0.2 | 2778 | London Chess Classic Grand Chess Tour Finals 2019 Standard Games |
| December 2019 | +2=0-0 | +1.6 | 2470\* | Ostlandsserien 2. div A 2019-2020 Round 1-2 |
| November 2019 | +4=7-0 | -6.0 | 2692 | 2019 FIDE Chess.com Grand Swiss |

Totals
+33=44-4

Percentages
+40.7=54.3-5

---
Tags: rating, elo
---


# Question
Title: Where can I find a list of commonwealth women's chess champions?
Note: Since I'm asking for improvement and downvotes in meta usually answer a yes/no question with 'no', I guess there's no room for improvement. Interesting...

---

I don't see a women's list here: Commonwealth Chess Championship.

In particular, I don't see any mention of who's the **current women's champion. Is it Tania Sachdev?** All I know is that Tania Sachdev won in 2019, and I wasn't able to find any references for any commonwealth chess or women's champions for 2020 or 2021.

(I guess none because of corona similar to British chess and women's chess, but US chess and women's chess still had theirs.)

# Answer
> 3 votes
From what I've been able to find I don't think you are going to find anything like a list of all Commonwealth women's chess champions.

First thing to check is what kind of organization is the Commonwealth Chess Association (the organisation which currently runs the championships). Looking in the FIDE Directory shows that has its own entry in the list of FIDE Affiliated Organizations and is based in Delhi with board members from India, Canada, Sri Lanka, Australia, South Africa, Scotland and Mauritius. So it has reasonably comprehensive commonwealth coverage.

It doesn't seem to have its own website but does have its own Facebook page. There the latest entry is from May this year about Covid and the previous one is about the 2019 championships. There is no mention of 2020 or 2021 championships so it is reasonable to assume that there weren't any.

Surprisingly the Commonwealth Chess Association's own Facebook page doesn't list the winners for any categories! It's almost as if it's not a serious chess organization. Digging further comes up with this article - Commonwealth Chess C'ship participants scammed by organizers.

This throws some doubt on just how serious (or otherwise) a championship chess tournament this is:

> According to the regulations, there is only one official entry per country in each category, but in this case, 700 participants across 16 categories enrolled in the event and interestingly, 644 players were from India.
>
> The open section for commonwealth saw 165 players, out of which only 31 were foreign participants from 7 countries and 134 from India. The top 24 seeds were from India. And there was not a single Grandmaster from any other country.
>
> **None of the hoards of players who were attracted to this event could achieve the International Master or Grandmaster Norm since the championship did not meet the criteria of having required number of Foreign titled players**.
>
> All those who participated from India received certification that they have represented India in the Commonwealth championship along with an official India T-shirt. Apart from paying a huge entry fee, these participants were forced to buy the India T-shirts from the organisers.
>
> The Junior Categories such as Under-10 Boys and Girls, Under-16 and Under-12 Girls saw only 2 foreign participants out of possible 53 countries which form the Commonwealth association.

I'm not quite sure what point the article is trying to make with "*only one official entry per country in each category*". According to the official FIDE prospectus for the 2018 event:

> **Entries**: Each Commonwealth country is eligible to field one man, one woman, One Senior (Above-60), one Junior Girl (Under-20), one Junior Open (Under-20) player and one open and girl entries each in under-8, 10, 12, 14, 16 and 18 as official entrants. Their boarding and lodging will be provided free in star hotel on triple sharing basis.
>
> Other entrants will have to pay for the boarding and lodging at $120 (Single) and $ 70 (Double sharing) per day.
>
> Please note that, the entry fee has to be paid by everyone unless qualifying for a free entry under the ‘Entry fee’ section.

So, only one entry per country is entitled to free accommodation, **sharing 3 players to a room**! However as many paid entries as the venue can accommodate are allowed.

However the point that this event didn't qualify as a norm event because not enough foreign titled players entered is pretty damning. In most countries when a norm event is held the required titled players are offered "conditions" which basically means free flights, accommodation (*not* sharing 3 to a room) plus extra money on top.

OK, so putting aside the lack of seriousness of the organizers, how can we find out past winners of the various categories of the Commonwealth Chess Association championships?

One obvious place to go is to check the chess-results website to see if Swiss Manager was used for the pairings and the results uploaded. Doing a tournament search on chess-results (enter "COMMONWEALTH CHESS CHAMPIONSHIP" in the first entry titled "Tournament" and click on "Search") shows that this did indeed happen in 2015 through 2019 and also in 2008 and 2010.

Looking through the 15 different championship categories for 2019 we see that there are separate open and girls events for U8, U10, U12, U14, U16, U18 and U20 and finally an open event. There is no separate event for seniors (O50 or O65) nor for women. Presumably because there were not enough entries in these events and so they all played in the open and the winners of these categories was the highest placed qualifier in the open.

This makes it more difficult to spot who the winners were in these categories given that the organizers didn't publish separate lists.

# Answer
> 0 votes
See wiki - Geography of chess - Supranational level:

Commonwealth Chess Association (CCA) has website: http://www.commonwealthchess.com/

Looks like current women's is Tania Sachdev, but I still don't see a list.

---
Tags: records, women, trivia, commonwealth, british
---


title: Bitboard chess engine design

text:
# Question
Title: Bitboard chess engine design
What are the best approaches to designing a chess engine? What classes/structures should it have? How are they connected to each other? I'm building a chess engine but I often find myself overwhelmed. I've learned from numerous resources (such as chess programming wiki) the algorithms for move generation, and have implemented them myself, but the design and structure of the whole thing is just generally a mess. If you've ever made a chess engine, how did you approach this?

# Answer
> 3 votes
> I'm building a chess engine but I often find myself overwhelmed

I can identify quite a lot with how you're currently feeling. So before I address your questions, I'd like to give some encouragement if I may.

I started working on writing a chess engine back in February of this year, so about 10 months ago. I still have the code from that first attempt I ever made at writing an engine. It was a mess, and I had no clue what I was doing, even though at that point I had been programming for a couple of years.

But one thing I will always give my past self credit for is that I learned a lot from that first attempt, and the second attempt was better...and the third, and the fourth, and the fifth, and so on. If I remember correctly I actually started over about *10 times* before I finally was able to create a solid codebase for the engine that I could start building from.

But every time I started over, my goal got a little closer, and I made sure I learned from my mistakes. So even if you're at the point where your code has just become too buggy or too messy to continue working from, that's alright. Learn from your mistakes this go-round, take some time to lick your wounds, create a new blank slate, and start again. If you keep persevering like this, I believe eventually you'll have something you can be very proud of.

With that out of the way, let me address the questions in your post:

> What are the best approaches to designing a chess engine? What classes/structures should it have? How are they connected to each other?

Here's how to think about things conceptually. A chess engine has three basic parts:

* Move generation: this phase generates all of the moves for a given position
* Search: this phase uses the move generator to generate all of the possible moves for the root position, and for each of those nodes generate all of their moves, and so on recursively until a certain depth is reached, or a checkmate or draw occurs. If the position isn't a checkmate or draw, then the engine needs some way of figuring out if the position it stopped at is good or bad for it, so this is where the evaluation phase comes in.
* Evaluation: This is the phase that looks at a given chess position and tries to assign an integer value for how good the position is for black or white.

Hopefully, you can start to see the connection between these three phases. The search is the heartbeat of any engine, and it makes calls to the move generation phase and the evaluation phase to do its job correctly.

Now, that's the 30,000 ft overview. As you've discovered, however, the implementation specifics are the hard part. Here is how I recommend you start.

* Move generator: You said you've already been working on this so that's good. I would recommend using a mailbox design like here. You'll need some different functions to generate moves for the different pieces as well. If this still seems daunting, there's are a lot of places you can find some pseudo-code. The CPW has some, but also search up "mailbox chess engines github" in google and look through some of the code you find to get some ideas. Once you have legal or pseduo-legal move generator, test it *throughly* using PERFT, on multiple positions. If that last link's format is confusing, read a little about FEN strings too.
* Search: You don't have to start off fancy here. You can just have a single function, copying the code here: https://www.chessprogramming.org/Negamax. Try to read a little to understand it. Then add some code in to clean things up to *your* liking. If you need to see some actually, feel free to look at an earlier version of my engine's search code here.
* Evaluation: again, starting off, simpler is better. Just count material. Let pawns be worth say 100 points, bishops and knights worth 300, rooks worth 500, and queens worth 900. And then count how many of each piece each side has, and multiply that by the value of the piece. As I'm sure you can tell, this is quite crude, as chess is much more than just material. But it's an excellent place to start!

Once you have these three parts written, implement a little bit of the UCI protocol and a time-management scheme so you can use your engine in a nice GUI, like Cute Chess or Arena. Again, if you need to see my code, there are many open-source engines on GitHub and other places. And always feel free to look at any code from my engine as well.

At this point, you should have a working chess engine. Will it beat a grandmaster? Probably not. It probably won't even be beating you very well. But the more important point is that you'll have somewhere you can *build from*.

Once you have the above implemented, start slow, and start reading about some ways to improve things. The next step could be to improve your move ordering and add a quiescence search phase. And after that, you can look into using piece-square tables, to start teaching your engine what squares are good for each piece type. And eventually, you can move on to techniques used in modern beasts like Stockfish or Komodo like pruning, and reductions, and extensions.

But again, *take things **slow***, and start off simple. You can always come back later and improve things. But if you start off trying to do every little thing, you'll likely end up with a very messy and buggy program that will be no fun to continue working on.

Hopefully, this helped to get you started down the right path. If you have any questions, feel free to fire away. I'd love to help out, and will try to answer when I have free time.

P.S: Make an account at talkchess.com. There are many smart people, many much smarter than myself, who can also give wonderful advice about how to begin the rewarding yet sometimes challenging process of writing a novel chess engine. I can't wait to see your engine rated on the CCRL soon! :-)

**Edit:** First, I realize I didn't make it clear, but if you wanted to look through the code, my engines code is posted here: https://github.com/algerbrex/blunder (hopefully this isn't marked as self-promotion.)

Second, I forgot to recommend some YouTube series that I highly recommend you watch if you need more help with a certain part of your engine:

Both creators are great programmers and even better teachers. Hopefully, those help as well!

---
Tags: engines, computer-chess, bitboard, chess-ai
---


# Question
Title: App which transforms chess moves into chess positions
I am interested is there an app which transforms written moves into chesd position? In other words, if I paste written chess game (for example 1. c3 d5 2. d4 Nf6 3. Nf3 Bg4 4. e3 e6 5. Be2 Be7 6. Ne5 Bxe2 7. Qxe2 Nbd7 8. Nxd7 Qxd7 9. Nd2 c5 10. dxc5 Bxc5 11. O-O O-O 12. Kh1 a6 13. e4 dxe4 14. Nxe4 Qe7 15. Bg5 Bb6 16. Qf3 Bd8 17. Rad1 e5 18. Rd3 Qe6 19. Nxf6+ Bxf6 20. Bxf6 Qxf6 21. Qxf6 gxf6 22. Rd7 Rab8 23. Rfd1 Kg7 24. g4 Kg6 25. Kg2 f5 26. R1d6+ f6 27. gxf5+ Kxf5 28. Rxh7 Rg8+ 29. Kf1 Rg4 30. Rf7 Rg6 31. h4 Rh6 32. h5 Rxh5 33. Rfxf6+ Ke4 34. Ke2 b5 35. f3# 1-0) is there an app which will transform this algebraic notation into chess position because I am too lazy to do it with real pieces and board. Thanks!

# Answer
What you're looking for is software/website that allows you to load or import PGN files.

The Lichess Analysis board, for example, supports exactly what you want: https://lichess.org/analysis -- below the board is a text area labelled "PGN", paste your moves in there and hit "Import PGN", and you can then navigate through your game.

All decent chess software can do this: SCID, ChessX, Chess.com, Chessbase. There are also PGN-specialised tools: ChessPad, PGN Edit.
> 17 votes

# Answer
My own website has two pages where you can paste chess notation and view it on an interactive chessboard and then save it as a link to be bookmarked or generate an animated image showing the whole game from start to end:

(1) old: https://www.apronus.com/chess/pgnviewer/

(2) new: https://www.apronus.com/chess/puzzle/editor.php (PGN import tab)
> 3 votes

# Answer
The app Lucas Chess has this functionality. It can import a PGN file (even one containing multiple games, in which case it puts up a spreadsheet-like window from which you can pick a game). But you don't even have to make a PGN file to contain your notation. Just "copy" (Ctrl-C) the text of your moves, and use Lucas Chess's "Paste PGN" feature.
> 2 votes

---
Tags: software, pgn, websites
---


title: Engine's 2nd best move

text:
# Question
Title: Engine's 2nd best move
Especially for checking studies (maybe also for teaching), it would be helpful to have an engine finding the second best move and assess it (or even give refutations of all alternatives). For a tablebase position, this is trivial. Can the Lichess/Stockfish engine do that? If not, do (especially online) alternatives exist?

# Answer
> 9 votes
Yeah engines can do it. Here's how you do it on Lichess:

Then when you run the analysis the engine gives three moves. You can increase the number of lines you want as well, which can be a waste since in this particular position, Black really only has one good move (...g6) so resources spent analyzing the 2nd-best (...Ke7) and 3rd-best (...Qf6) moves are wasted.

# Answer
> 3 votes
I'm not the biggest fan of chess dot com. As a 9LX player I of course prefer lichess but even chess dot com has this.

Just click show lines to get

the following

Go to settings to adjust number of lines:

---

Btw this is how it looks like on lichess:

Just 1 line:

Find multiple lines:

The final product:

---

What surprises me in particular about OP's question is that multiple lines option helps show how sharp/critical a position is. Eg I loaded a puzzle on lichess and here's what I have:

The red circle/oval/ellipse shows the only good move for black (good here means winning, not winning-or-drawish). The orange box shows there are 2 drawish moves. Finally the blue box shows the (least) bad moves (meaning \[the least\] winning for white). This setup of arranging by least to greatest evaluation shows that any other move is bad

---
Tags: engines, analysis
---


# Question
Title: Do main lines score significantly better?
Even at highest levels players make significant, but human, mistakes. On the other hand there exists a great amount of opening theory, with lines studied in depth, especially the mainlines. Isn't the precision of theory evaluation and human imprecision in contradiction? Is it generally difficult to punish small opening sins even at the highest (human) level (Evans-Gambit, Cozio defense, 1. ... a6)? If so, is the fact that most advanced players learn and play some kind of mainlines just some kind of gentlemen's agreement? Or do they score significantly better?

# Answer
The score of openings is more often a combination of the strength of players which play it, the situations in which the openings are played, and of course the objective merit of the opening. Looking at the database you will often see sidelines which have much higher scores than mainlines, often these are trendy lines which are played by players who are up to date on theory and playing for a win against weaker opponents. That doesn't mean these lines are objectively better than main lines, most of the time main lines follow a traditional ~51% type of score, as strong players are often choosing them when playing to be solid.

For a specific example lets consider the Nimzo-Indian: 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4. Here the three most popular moves 4.e3,Qc2,Nf3 all score around 52% (megabase), the sharp and trendy 4.f3 scores 53.5% and the old line 4.a3 scores a miserable 46%. These are all main lines and the only conclusion I would infer from these numbers is that strong players are playing 4.f3 for a win against weaker players. While black players in general find it easiest to win against 4.a3. If I was playing a player rated 400 points below me I would be much more tempted to play 4.f3 as I know the chances of them making a mistake is much higher than me making a mistake. However if I was playing a player 400 points above me, I would rather play a safer move like 4.Qc2, as there even if I make some small mistakes it will be easier to hold a draw.

To refer to the first part of your question, I am certain that all of these 4th moves in the Nimzo-Indian contain long theoretical lines which end in drawish positions. In a practical game between human players however it is more important who has a better understanding of the position, and luring your opponent into a position which you understand better than they do is one of the main goals of the opening. So in the end the score of an opening is largely irrelevant. Main lines are fundamentally sound positions which often afford players to make small mistakes without serious deteriation of the position.
> 3 votes

---
Tags: opening, theory
---


# Question
Title: Where can I watch World Chess Championship 2021?
What are the possible streams that I can watch World Chess Championship 2021 from 24th of November to 16th of December (any online platform and television broadcast)?

If possible, please provide information about who will be the casters and whether the stream will have the live feed of Carlsen and Nepo.

# Answer
> 21 votes
**Chess24 Global** is providing commentary with David Howell, Jovanka Houska and Kaja Snare.

**Chess24 Deep Dive** is providing commentary with Anish Giri and Judit Polgar.

**Chess.com** is providing commentary with Robert Hess, Danny Rensch, Fabiano Caruana and Hou Yifan.

**FIDE** themselves are providing commentary on YouTube by Vishwanathan Anand and Anna Muzychuk.

And a number of other sources are also available for dedicated commentary via streaming (**Hikaru Nakamura**, **Ben Finegold**, **ChessBase India**, ...)

You're spoilt for choice really.

# Answer
> 5 votes
According to this tweet from Chess24.com they will be broadcasting the event:

> We all know @DavidHowellGM from his ace commentary of the Meltwater @ChampChessTour. Now the three-time British champ (and former junior rival of Carlsen and Nepomniachtchi) is back to guide us through the FIDE World Championship on the #c24Global broadcast.

# Answer
> 4 votes
You can watch it on Chess.com. you can follow the live moves with computer analysis, live chat, and video commentary by grandmasters and special guests. I think Viswanathan Anand will be one of the official commentators and Caruana will also be joining in this commentators team.

# Answer
> 4 votes
If we're accepting non-English mentions, the Norwegian Broadcasting Corporation (NRK) will be following the games live, presumably with commentary by IM Torstein Bae with others, in Norwegian. That link currently claims it will be available worldwide (I don't think it was in 2018).

Historically their coverage has been aimed at a more casual audience (I expect them to explain things like en pessant and the restrictions on castling at least once during the games, along with relevant fundamental endgame theory like K vs K+B being a forced draw), and they have a funny fascination with the Stockfish evaluation ("pila", the arrow). But as a somewhat casual player myself, I have found it enjoyable in the past.

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Tags: world-championship
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# Question
Title: King's alternative routes to reach a destination square
What are the alternative routes that king can go to destination square like king can go from one edge to another edge in 7 moves but it has many alternative paths to reach there in 7 moves.

Please provide one or two practical endgame examples in which going through an alternative route makes a difference.

# Answer
Brian's answer is sufficient, but I like to extend it with a few observations that are too long for a comment.

* "edge, 7 moves, alternative path" is a bit unprecise: if the edges are diagonal, of course the shortest path is unique.
* OK, assume start and destination are given. How do you actually compute the number? This can be done with Pascal's triangle technique. Assume you want to go from e3 to e7 to keep it simple. Then d4,e4,f4 get a "1" (only one path that leads there). c5 gets "1" (ditto) but d5 "2" (accessible from d4 *and* e4, so sum) and e5 "3". And so on, e7 gets "19" and that is the total number of shortest paths.
* Brian's example does not tell you "why" of it. There are the following main reasons for picking a certain route of several possible:
* Mutual Zugzwang. This happens even in the simplest KP/K endgames, thus you may choose a path catching the opponent K on the wrong foot.
* Multitasking. For example, the famous Reti KP/KP study. The king marches diagonally since on this path it can fulfil two purposes at the same time, hunting the enemy pawn and supporting its own.
* Shouldering. Arguably a special case of the former. You walk the path that on the same time denies the enemy K some squares. A study with only KP/KP exists for this either.
* Check avoidance. It can happen that squares on your routes are "mined" for some tactical reasons, mostly an enemy check winning a tempo. Well, just march around them.
> 3 votes

# Answer
The main important difference is that the diagonal is the same number of moves as the orthogonal.

> Please provide one or two practical endgame examples in which going through an alternative route makes a difference

```
[fen "K7/6p1/7p/8/8/8/7P/k7 w - - 0 1"]

1. Kb7 (1. Kb8 h5 2. Kc8 h4 3. Kd8 g5 4. Ke8 g4 5. Kf8 g3 6. hxg3 hxg3 7. Kg8 g2 8. Kh8 g1=Q) h5 2. Kc6 h4 3. Kd5 g5 4. Ke4 g4 5. Kf4 g3 6. hxg3 h3 7. Kf3 h2 8. Kg2 h1=Q 9. Kxh1) (6...hxg3 7. Kxg3)

```
> 2 votes

# Answer
The classic example of this is a Richard Reti endgame study from 1921. (https://www.chess.com/forum/view/more-puzzles/the-reti-endgame-study is a link; it's the second study.)

The punch line is the white King *has* to take the diagonal path, essentially getting one square closer to catching the black pawn while at the same time getting one square closer to supporting the white pawn's promotion. The dual threat forces a draw.
> 1 votes

# Answer
I forget the exact details enough to be able to find it easily; but I think one of the Korchnoi - Karpov World Championship matches was lost because Korchnoi forgot something like Kd3-e4-f3 was possible (as opposed to Kd3-e3-f3).
> 0 votes

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Tags: endgame
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# Question
Title: What chess book or teaching approach is this from my childhood?
When I was little (mid-late 90's) my mom taught me to play chess. She had a book, which looked pretty old at the time (perhaps from the 70s but I could be off by a decade or more). The book outlined the approach she used to teach me.

As the first step, she taught me only about the pawns. We played entire games with ONLY the pawns. Each player had eight pawns set up on their second row (the same positions as in normal chess), and the pawns moved exactly as in chess, including capturing *en passant* when legal. The object of this game was to either get a pawn to the other side of the board, or to capture all the opponent's pieces. This was a great game and a great introduction and was very easy to learn and remember.

My trouble is, I don't recall what the next step was. It may have been to introduce rooks and play the same game but with rooks added. That rings a bell, but I'm not sure.

I'm now teaching my 7-year-old son to play chess, and I'd love to be able to use the same approach I learned with as I know it was successful although I don't remember the rest of the details of the gradual approach. (My mother passed away a couple years ago so isn't available to ask about it.)

Does anyone recognize this approach? Does it have a name? Is there a book (either a well known book or an obscure one) that uses this method as the first step toward teaching chess to a beginner? (The book may have been giving an approach specifically for teaching children, or just a general method of teaching chess, I'm not sure.)

# Answer
Sounds like the Lev Alburt/Sam Palatnik series (Comprehensive Chess Course, a two-volume set at the beginning, with Alburt adding more volumes to it later).

Both volumes are widely available used; should be able to find them readily for cheap, if you don't mind the odd tear or stain.
> 2 votes

# Answer
You can make it up yourself as you go along. You already know that chess is better learned with as few pieces on the board as possible, which puts you way ahead of the people who want to teach newcomers with all 32 units.

At the first meeting of a 10- or 12-week class, I teach the kids a game with eight white pawns and the black queen. If a pawn reaches the 8th rank (unlike chess, it doesn't have to survive the 'promotion'), the pawns win. If the queen gobbles all the pawns or blocks the last pawn remaining, the queen wins.

Some kids never get past that, but they get to enjoy the play time instead of struggling with chess, and the great thing about it is that it's an equalizer. I lose some of those games, and unlike chess, when I talk about why I'm making this move or that, the kids understand.
> 4 votes

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Tags: books, teaching, children
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# Question
Title: How much should I rely on an external board or diagram when reading a chess book?
I'm currently making my first serious attempt to read a chess book. While I can generally follow and evaluate variations mentally if I can at least see the starting position in some diagram, I struggle after the variations continue beyond the page and I can no longer see a diagram from which the variation departed.

I can copy the diagram on a board or simply on my computer (and do not move the pieces), but I wonder whether I should. On the one hand, being forced to remember and visualize the diagram trains my visualization skill. On the other hand, I catch myself flipping the page quite a few times and I wonder if this distraction is worth the trouble. I certainly don't intend to play blindfold, so I will always have *some* chess position in front of me when I need it, at least.

Now that I think about it, I'm not even sure whether it is good that I do not play the variations out on a board or computer diagram: I might miss things that the book doesn't want to spend time on, or spend too much effort on skills I should not be training. I have no clue, really.

How can I determine what would work for me here? Are there any texts out there that cover this issue? The book itself doesn't give much suggestions on how to read the variations beyond thinking on your own before reading the suggestions in the book, which I do.

---

This question is related, but I'm not really looking for what is *common*, I am looking how I can determine what is *good for me*, or what chess teachers believe is a didactically effective approach. (based on reasoning or experience)

# Answer
> 8 votes
> I can copy the diagram on a board or simply on my computer (and do not move the pieces), but I wonder whether I should.

It is very much worth while setting up a board and following the game on the board. But you should go beyond just passively playing out the moves on the board. You should stop after each move and actively consider what you would play next for each side. That will benefit you much more.

There is also the aspect of involving more of your 5 senses as I say in this answer to a different question.

# Answer
> 2 votes
Nimzovich recommended using two sets: One follows the actual game text, while you use the other for following the analysis -- this way you never lose the game position during analysis. In my youth I did this with a regular set for the main text, and a magnetic one for analysis. These days, if you're comfortable with computer boards, you can do with either multiple computer windows, or a PGN reader that allows direct entry of moves. Or any combination of electronic and physical boards.

Try several different approaches, see what feels comfortable to you. Even these days I prefer to have at least one set that resembles the sets I play tournament games on, but that's just me.

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Tags: learning, books, visualization
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title: Collection of short endgame rules

text:
# Question
Title: Collection of short endgame rules
Are there any resources with a list of short endgame facts and rules ? For instance : "2 connected pawns on the 6th rank always win against a rook" , "rook's pawn results often in a draw in KPvP endings".

Or do I have to necessarely go through an endgame manual to find this information ?

# Answer
"Dvoretsky's Endgame Manual" is exactly one such book that contains a lot of these short facts. You can treat it similarly to an encyclopedia in that regard. Throughout, he writes these key tidbits of advice in italics like so:

I will caution you though that the actual meat of this book is incredibly involved and is most appropriate for players \>2000 OTB. There are other books out there that contain the most simplified bits of advice. Shameless plug for my own set of lichess studies on the endgame that contains exactly those bits of info that I think are most relevant without the most complicated examples. I've linked to the study for advanced players, but there are also studies for beginners, studies for intermediate players, and studies specific to rook endgames linked throughout. I describe the "rules" of king and pawn endgame races as follows:

Finally I can address your exact question. The endgame is the portion of the game where one must calculate the most precisely. These general rules are helpful to help guide one's thoughts, but remember: *nothing beats a good move.* There are countless counterexamples to the general principles. Without an endgame manual or similar to show you how and why the general facts/rules work *and fail*, the rules are not so useful on their own. So yes you should necessarily go through guided material that presents the rules. No you should not just read the rules by themselves.
> 7 votes

# Answer
The golden rules of converting a won endgame -

1. 1. The Plan - schematic thinking. Creating step-by-step plans that lead to eventual success make playing the game easier. Apart from methodology, it has a great psychological effect because we don't concentrate on winning a difficult position but on something which is close at hand (e.g. creating a passed pawn).
2. Exchange - When there are not many pieces left on the board, every exchange counts. It's extremely important to consider your exchanges carefully as there's no time and possibility to obtain compensation. Consequences are severe!
3. Restricting your opponent's possibilities (to maximum) - Every single player should master the art of prophylactical thinking. Even the smallest sign of activity should be put down immediately. It's one of the most important rules.
4. No rush! - When redeeming the advantage, it's crucial to remain calm and play solid chess even if other possibilities are more tempting. We should consider all of the possible options and before undertaking any measures that drastically change the situation on the board, improve our own position at most. "No rush" doesn't mean unnecessary loss of time. On contrary, every single tempo counts.
5. Two weaknesses rule - If our opponent is pushed into defense, the play should be conducted on the whole board. Creating new weaknesses, problems and attacking them alternately.
6. Transformation of the advantage - It's a rare situation when there's only one type of an advantage during the endgame. Chess is a dynamic game and in most cases it's beneficial to change one type of the advantage to another one (e.g. sacrifice an exchange in order to queen the pawn). These rules are for converting a won endgame, doesn't answer your question, but I hope it was helpful.
> 4 votes

# Answer
I think the book "100 endgames you must know" by GM Jesus de la Villa (sample pages) comes close to what you describe. The book is much more than just "facts", but it tries to summarize each of the titular 100 endgames with a short sentence which describe the situation. The second part, of what must be done, will be left for you to summarize, after you read the explanation.
> 2 votes

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Tags: endgame, learning
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# Question
Title: What happens if you touch a piece that cannot move?
I heard that in formal games you have to move the piece that you touch first. What if the piece cannot move, as in there are no legal moves that involve that piece? What would happen in that circumstance?

# Answer
> 30 votes
The laws of FIDE state in article 4.5 that "If none of the pieces touched can be moved or captured, the player may make any legal move."

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Tags: rules
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# Question
Title: Is Agasthya Smriti containing the Original Chess Strategy available in public Domain?
Saint Agasthya was the most knowledgeable person of the 8000 yrs ago period. He is credited for:

1. The Martial Arts (Kalari Paytu),
2. Chemical based Medicines specially for Venom treatment,
3. Game of Chess called "Shad Yantra" of 100 Squares,
4. Beautifully written Tamil Script and Language,
5. Got Entire Land of Sri Lanka given to him by MahaBali, as Vaman (Dwarf) Avtar.

It is said that Agasthya Smriti (Memoirs of Agasthya) has summary of his all inventions and actions, including Agasthya Suktam. Agasthya Suktam is said to be a chapter about how to manage WAR and play Chess Game with pieces.

# Answer
Yes, it is in the public domain, assuming you can find a copy of it online or in a library. His works are from many years ago, if what you say is accurate. Copyright law simply does not apply.
> 1 votes

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Tags: history, books
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title: Rating effect on no-show

text:
# Question
Title: Rating effect on no-show
In a long time control (90+30) team championship game I showed up on time but wrong city and lost the game - will this affect my rating? I arrived at the wrong location and missed the game.

# Answer
According to the latest FIDE rating regulations your game was not played and therefore will not be rated. Both players must make at least one move before the game can be rated

> 5. Unplayed Games 5.1
>
> Whether these occur because of forfeiture or any other reason, they are not counted. Any game where both players have made at least one move will be rated.
> 9 votes

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Tags: rating, fide, elo
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title: What should Black do?

text:
# Question
Title: What should Black do?
I am reading “Ten Ways To Succeed In The Opening“ by Tim Onions and David Regis. On page 48, there is a problem I am trying to solve.

However, I can’t figure out what Black should do next.

# Answer
I feel some doubt about this book. It is self-published by writers who are not well-known. I am sure they have in mind 1..Qh4 with some followup like 2 0-0 Nf6 3.h3 (to prevent Ng4) Bxh3 4.Qxa8 Qg3. A much better defence for White is 2. d4! and I do not think that Black is winning at all. If 2...Qxe4+ 3.Be3 and Black must prevent Qxh7 so 3...Nf6 4.dxc5 and White looks fine, or if 2...Bb6 3.Nd2 followed by Nf3. I dont think you need to reproach yourself with missing anything
> 6 votes

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Tags: problems, attack
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# Question
Title: In French Defense Advance Variation, why does white play an early f4?
Game.

First five moves:

```
[FEN ""]

1. e4 e6 2. d4 d5 3. e5 c5 4. c3 Nc6 5. f4

```

Why did white play f4?

My guesses:

* To defend e5 in case if d4 falls.
* Pawn pointing theory seems to indicate that white wants to launch kingside attack because black more often castles kingside.
* To control more squares in center.

But doesn't f4 weaken white king?

# Answer
As suggested, I'll convert my comment to an answer. Given this format however, I reckon a list makes more sense. So let's see how the move 5.f4 changes the position:

* 5.f4 is a slow move that wastes time for white in a line where White already invested a tempo on 3.e5.
* 5.f4 makes it easier for Black to develop their knight on g8 via h6, from where it lands on a great square on f5.
* 5.f4 weakens the diagonal g1-a7, making it more difficult for White's king to find safety.

So, to answer your question: White played 5.f4 in the game you linked because White wasn't a very strong player, not because 5.f4 was a good move. While it doesn't lose the game for White, it makes Black's game far easier, and White will be the one who has to solve some serious opening problems if Black knows how to turn the screws.

The best move in the position is the main line, 5.Nf3. This move defends d4 and develops White's knight. It also lets White retain control of the e3 square, which means that White's dark-squared bishop has a safe square on e3 to develop to.
> 6 votes

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Tags: analysis, french-defense
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