title: Crazyhouse/Bughouse openings

text:
# Question
Title: Crazyhouse/Bughouse openings
Are there any known or "standard" openings in bughouse or crazyhouse chess? Obviously, as soon as pieces start coming off the board things get less predictable, so this question is less about the existence of opening *lines* as it is about *moves* which are consistently seen to be good; e.g. White playing `e4` to open development lines, or Black avoiding `g6`, which creates exploitable weaknesses.

# Answer
I play `1... Nf6` after `1. e4`. Then `2. e5 d5 3. exf6 exf6`. I have had great scores with this opening versus Chess master.

```
[FEN ""]

1. e4 Nf6 2. e5 d5 3. exf6 exf6

```

The idea is to have strong king side with 4 pawns for defence. The second advantage is the development. Bishop in c8 is ready for attacks. If white castle king side u can put pawn in h3 if g*h3, B*h3 or @Nf3+.
> 9 votes

# Answer
This reddit page has plenty of good advice, and mentions a (strong player's) opening repertoire (section "My Opening Systems").

Excerpt :

> For White:
> Modified Catalan
> Basic setup: 1. d4 ... 2. g3 ... 3. Bg2 ... 4. h3 ... 5. Nf3 ... 6. Bg5 ... 7. 0-0 ... 8. Nbd2
>
> Themes: Solidify and fortify your king before you attack. h3 is an important move so your opponent can't place a pawn there attacking your fianchettoed bishop. You start out a bit passive but extremely solid. Black will have a hard time breaking through while you use the time he's trying to drum something up to form an attack of your own on his likely more exposed kingside. Trade pieces in the center and then drop on the kingside. Often p@e5 to challenge the center or a pinned piece or p@h6 to pry open the king. You can allow the f3 knight to be captured, whereafter you'll often recapture with the e-pawn to build a nice box around your king. If they sac on h3, capture and then simply replace the pieces right back where they were. If no tension develops after the first 8 moves and there is no obvious attacking idea, bring a rook to c1 and break with c4 (or just play c4 immediately) to trade pawns and open things up.
>
> Illustrative Game: http://en.lichess.org/THYYswroKIlD
>
> \[NdT : there's this length of description for all the lines listed below\]
>
> Modified Chigorin/Trompowsky: 1. d4 ... 2. Nc3 ... 3. Bg5 ... 4. Nf3 ... 5. e3 (or e4, if allowed) ... 6. Be2/d3 ... 7. 0-0
> e4 systems: 1. e4 ... 2. Nf3 ... 3. Bc4/b5/e2 ... 4. d3 5. Bg5/f4 ... 6. Nc3 or Nbd2 followed by eventual c3 ... 7. 0-0
> Offbeat stuff: 1. b3 ... 2. Bb2 ... 3. e3 ... 4. d3 ... 5. Nf3 ... 6. Be2, stuff like that.
>
> For Black
> Crosky Gambit : 1. e4 Nf6 2. e5 Nc6!? 3. exf6 gxf6! 4. ... d5 (can transpose with 2. ... d5 instead of Nc6) 5. ... Rg8 6. ...Bg4 7. ...e6
> Modified Modern : 1. ...g6 2. ... Bg7 3. ...Nf6 4. ...h6 5. ...d5 6. ...Bg4 7. ... 0-0 8. ...Nbd7 or Nc6
>
> (and more)
>
> **tl;dr**: Beginners may be best served by playing conventional e4/d4 systems as white and the French as black. Avoid pawn moves which weaken key squares; fortify weak squares around your king. Maintain the initiative and attack. Sac when it draws the king out and you have a follow-up. Emphasize king safety over material gain. Calculate what your opponent (and you) can do with exchanged pieces before entering into tactical complications. Go crazy!
> 8 votes

# Answer
## Crazyhouse openings repertoire

See my lichess study. All moves have been cross-checked with an opening book of 2000+ rated players. Moves that the opponent is likely to play and moves that give a human the best practical advantage and winrate are chosen. When lines deviate from engine recommendations, they are marked as dubious but with high practical chances.

### A complete repertoire for white 1.e4 players

Abbreviated overview. See `1.e4 Overview` chapter for more.

Some of these moves may look a bit crazy without a proper crazyhouse PGN viewer.

```
[Event "Crazyhouse Openings: 1.e4 Overview"]
[Site "https://lichess.org/study/vPETXYUF/JRY7gzah"]
[Variant "Crazyhouse"]
[White "You - vs"]
[Black "Someone else"]
[Annotator "https://lichess.org/@/sicariusnoctis"]
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR/ w KQkq - 0 1"]
[SetUp "1"]

1. e4 { Don't panic. :)

This study contains various opening lines designed (statistically) to give practical advantages for players at the 2000+ rating. Moves that lead to statistical advantage are chosen. The most frequently played responses by opponents also taken into account. Needless memorization is avoided where no significant advantage can be found by suggesting a transpositional move. This is not the only set of valid lines, nor is it always necessarily "optimal". That depends on your style. Take this as a reference, and create your own repertoire. There are various strong and "trappy" lines that I have certainly missed.

Chapters are ordered from greatest to least "importance" or line popularity at the 2000+ rating level. Study the early chapters (Italian, Nimzowitsch, Alekhine, French, and 1.d4) well! Chapters not marked "[as Black]" are from the perspective of white. Not all chapters are complete -- they are constantly evolving as I learn and discover new lines. The lines that come up most frequently in my own games are covered in greater depth and detail than ones that don't, if they are covered at all.

This chapter is an overview of the 1.e4 lines for white which are covered in this study. If you are looking for a good starting point, memorize these first, then look deeper into the ideas discussed in the other chapters.

Share and enjoy! } e5 { C20 King's Pawn Game [30% of games.] } (1... Nf6 { B02 Alekhine Defense [22% of games.] } 2. Nc3 { From here, 2..Nc6 transposes into the Nimzowitsch Defense, given below as 1..Nc6. } d5 { B02 Alekhine Defense: Scandinavian Variation [8% of games.] } 3. exd5 Nxd5 4. Bc4 e6 5. Bxd5?! exd5 6. Qe2+)  (1... e6 { C00 French Defense [21% of games.] } 2. d4 d5 (2... d6 { C00 Rat Defense: Small Center Defense [2% of games.] Develop naturally, then play e5 for a kingside attack. } ) 3. Nc3 { C10 French Defense: Paulsen Variation })  (1... d5 { B01 Scandinavian Defense [7% of games.] } 2. exd5 Qxd5 3. Nc3 { Most common continuations: Qa5, Qd8, Qe6+, Qe5+. })  (1... Nc6 { B00 Nimzowitsch Defense [6% of games.] } 2. Nc3 { Stops d5. } 2... Nf6 { [11% of games.] Frequently arises out of the Alekhine Defense. This is an important position to study. } (2... e6 { B00 Nimzowitsch Defense: French Connection } 3. d4 Nf6 4. Nf3 Bb4 5. Bd3 d5 6. e5 Ne4 7. O-O) 3. d4 d5 { B00 Nimzowitsch Defense: Scandinavian Variation, Bogoljubov Variation, Vehre Variation } 4. exd5 Nxd5 5. Nf3 Bg4 6. Bb5 e6? 7. P@a6!)
2. Nf3 Nc6 { C44 King's Knight Opening: Normal Variation [27% of games.] }
3. Bc4 Bc5 { C50 Giuoco Piano [16% of games.] } (3... Be7 { C50 Italian Game: Hungarian Defense [6% of games.] } 4. d4 exd4 5. Nxd4)
4. O-O Nf6
5. d3 O-O
6. Nc3 d6 { [10% of games.] Most typical position of the Giuoco Piano, occurring 60% of the time in Italian lines with this repertoire. Various move orders converge to this point. }
7. Ng5 Bg4?! { [3% of games.] } (7... Nd4?! { [3% of games.] } 8. Be3 { Gives white the ability to win a knight to replace the current one on g5 after Nxf7 is played. } 8... c6? { For example. } 9. Nxf7)  (7... Qe7 { [3% of games.] } 8. Nd5 Nxd5 9. Bxd5 $14)
8. Nxf7 Rxf7
9. Bxf7+ Kxf7
10. Qxg4 { Preparing B@h5+ fork after 10..Nxg4. }

```

Openings covered, listed in order of line popularity:

* 1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 Italian: Giuoco Piano
* 1.e4 Nc6 Nimzowitsch (often transposes from Alekhine)
* 1.e4 Nf6 Alekhine
* 1.e4 e6 2.d4 French
* 1.e4 d5 Scandinavian
* 1.e4 c5 Sicilian
* 1.e4 e6 2.d4 d6 Rat Defense
* 1.e4 e5 2.Nf3 d6?! Philidor
* 1.e4 e5 2.Nf3 Bc5?! Busch-Gass Gambit
* 1.e4 e5 2.Nf3 Nf6 Petrov

### A complete Italian-Hungarian repertoire for black against 1.e4

Abbreviated overview. See `1.e4 Overview [as Black]` chapter for more.

Some of these moves may look a bit crazy without a proper crazyhouse PGN viewer.

```
[Event "Crazyhouse Openings: 1.e4 Overview [as Black]"]
[Site "https://lichess.org/study/vPETXYUF/QXxmMVDM"]
[Variant "Crazyhouse"]
[White "Someone - vs"]
[Black "You"]
[Annotator "https://lichess.org/@/sicariusnoctis"]
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR/ w KQkq - 0 1"]
[SetUp "1"]

1. e4 { [72% of games.] } 1... e5
2. Nf3 { Also seen are 2.Nc3 (Vienna Game) and 2.Bc4 (Bishop's Opening), but these usually transpose into an Italian. } 2... Nc6
3. Bc4  (3. d4 { C44 Scotch Game [6% of games] } 3... exd4 4. Nxd4 Qh4?! { Trappy. Works best <2000, though. })  (3. Bb5 { C60 Ruy Lopez [5% of games] } 3... Bc5 { This is a nice move order to reduce variations (d3, Nc3) and induce castling. 3..Nf6 is what I usually play, though. Note that 4. Bxc6? is a mistake due to 4..Bxc6 5.Nxe5? Qd4! }) 3... Be7 { C50 Italian Game: Hungarian Defense [46% of games.] }
4. O-O?! { [14% of games.] } (4. Nc3 { [10% of games.] } 4... Nf6 5. d4 { [3% of games.] } 5... exd4 6. Nxd4 d5 { Example continuation: 7. exd5?! Nxd4 8. Qxd4 P@h3 9. P@e6?? hxg2 10. exf7+ Kf8 })  (4. d4 { [9% of games.] } 4... exd4 5. Nxd4 Ne5 { [8% of games.] } 6. Nf5 { [3% of games.] } (6. Bb3 { [2% of games.] } 6... d5 7. exd5 Bc5)  6... Bf6 { Usually continues with a sharp line, 7. P@g5 P@h3 })  (4. Bxf7+?! { [7% of games.] } 4... Kxf7 5. P@d5 Bf6)  4... Nf6
5. d3 { [6% of games.] } (5. Nc3 { [4% of games.] } 5... O-O 6. d4? { [0.5% of games.] } 6... exd4 7. Nxd4 { Next, 7..P@h3. Indeed, Nxd4 Qxd4 N@f3 fork is the main idea. Also, play d5 soon to open our bishop and block white's. }) 5... O-O
6. Nc3 { [2% of games.] } 6... d6 { [19% of games.] Most typical position of the Italian Game: Hungarian Defense, occurring 40% of the time in Italian lines with this repertoire. Various move orders converge to this point. }
7. Bg5?! { [4% of games.] } (7. Ng5 { [5% of games.] } 7... Nd4 8. Be3 Qe8 { Preparing a Queen sacrifice via 9. Bxd4 exd4 10. Nb5 Qxb5?! 11. Bxb5 Bg4})  (7. h3?! { [4% of games.] } 7... Na5 { One typical idea is to take the bishop, then B@d7-Bxh3. For example, 8. Bb3 Nxb3 9. axb3 B@d7 10. N@d5?? Bxh3 })  7... Bg4
8. Bxf6?! { [1.8% of games.] } (8. h3?? { [1.6% of games.] Common mistake allowing a devastating attack. } 8... Bxf3 9. Qxf3 Nd4 10. Qd1 Nxe4! 11. Bxe7 Nxc3 12. bxc3 P@e2) 8... Bxf6
9. Nd5 B@h5 $17 { Main idea is to trade everything on f3, decimate white's kingside pawn structure, and checkmate. Best move here for white is N@g3, which is rarely played, and is still quite advantageous for black. N@d2 allows Nd4, and Nxf6-Qxf6-N@d5 falls into a typical queen sacrifice, Qxf3! }

```

Openings covered, listed in order of line popularity:

* 1.e4 e5 2.Nf3 Nc6 3.Bc4 Be7 Italian: Hungarian Defense (**important:** 70% of 1.e4 games!)
* 1.e4 e5 2.Nf3 Nc6 3.Bb5 Ruy Lopez
* 1.e4 e5 2.Nf3 Nc6 3.d4 Scotch
* 1.e4 e5 2.Nc3 Vienna

The primary opening I play as black is the solid "Italian: Hungarian Defense" which has a good winrate and is engine approved. Other strong openings are:

* Italian: Hungarian Defense
* Alekhine: Scandinavian variation (60+% WR at 2000+ rating!)
* French
* Nimzowitsch

### Using this resource effectively

To use this resource effectively, I suggest maintaining your own study and including lines you encounter in your own games. Then, my study can be used as a reference point or to provide commentary. Or, you can look directly at the opening book, since that's where I have taken many of the ideas from. I also recommend completely memorizing the short "Overview" chapters, which are fairly minimal on purpose.
> 5 votes

# Answer
according to engine, the italian game is good, and the best reply to the italian is 3...d6. In crazyhouse, avoiding the fried liver is important for players of all level cause crazyhouse give white big attacking chances!
> 3 votes

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


# Question
Title: Is today's World Championship game the first with a symmetrical position and one file completely occupied?
After 8 moves in the 8th game between Carlsen and Nepomniatchi this position was reached.

```
[FEN "r2qk2r/pppb1ppp/3b4/3p4/3P4/3B4/PPPB1PPP/R2QK2R w - - 0 1"]

```

The position is perfectly symmetrical and the d file is completely occupied by pieces. Is this the first time something like this has happened in a World Championship match?

# Answer
Using this CQL query:

```
cql(input all_wcc.pgn)

[Aa][a1-8] == 8
or [Aa][b1-8] == 8
or [Aa][c1-8] == 8
or [Aa][d1-8] == 8
or [Aa][e1-8] == 8
or [Aa][f1-8] == 8
or [Aa][g1-8] == 8
or [Aa][h1-8] == 8

square all Square in .
 colortype Square == -colortype makesquare (file Square 8 - rank Square + 1)

```

and running it against a PGN that contained all the World Championship games (collected from Mega Database according to Wikipedia \- 2.22 MB) indicated that such a position first occurred at the 5th World Championship (1894) between Lasker and Steinitz:

```
[FEN ""]
[Event "World Championship 5th"]
[Site "USA/CAN"]
[Date "1894"]
[Round "17"]
[White "Lasker, Emanuel"]
[Black "Steinitz, William"]
[Result "0-1"]
[ECO "C50"]
[StartPly "10"]

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.d3 Nf6 5.Nc3 d6 6.Be3 Bb6 7.Qd2 Na5 8.Bb5+
c6 9.Ba4 Bxe3 10.fxe3 b5 11.Bb3 Qb6 12.O-O Ng4 13.Rae1 f6 14.h3 Nh6 15.Ne2 Nxb3
16.axb3 O-O 17.Ng3 a5 18.d4 Nf7 19.Qf2 Ra7 20.Rd1 a4 21.b4 Qc7 22.Ne1 c5 23.Qd2
Be6 24.d5 Bd7 25.Ra1 cxb4 26.Qxb4 Rc8 27.Qd2 Qc4 28.Rf2 Ng5 29.Qd3 Rac7 30.h4
Nf7 31.Qxc4 Rxc4 32.Rd2 g6 33.Kf2 Nd8 34.b3 R4c7 35.Rdd1 Nb7 36.Rdb1 Kf7 37.Ke2
Ra8 38.Kd2 Na5 39.Kd3 h5 40.Ra2 Raa7 41.b4 Nc4 42.Nf3 Ra8 43.Nd2 Nb6 44.Rf1
Rac8 45.Nb1 Ke7 46.c3 Nc4 47.Raf2 Na3 48.Ne2 Nxb1 49.Rxb1 Bg4 50.Rc1 Rc4 51.Rc2
f5 0-1

```

Then at the 6th World Championship (1896) between the same players:

```
[FEN ""]
[Event "World Championship 6th"]
[Site "Moscow"]
[Date "1896"]
[Round "6"]
[White "Lasker, Emanuel"]
[Black "Steinitz, William"]
[Result "1-0"]
[ECO "C50"]
[StartPly "8"]

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Nc3 Nf6 5.d3 d6 6.Be3 Bxe3 7.fxe3 Na5
8.Bb3 Nxb3 9.axb3 Ng4 10.Qe2 f6 11.d4 c6 12.O-O-O Qe7 13.h3 Nh6 14.g4 Bd7 15.
Nh4 g6 16.Nf3 Nf7 17.Rdg1 O-O-O 18.b4 Kb8 19.Qf2 Rdf8 20.Qg3 h6 21.Rf1 Nd8 22.
Rhg1 Ne6 23.Rf2 Nc7 24.Rgf1 Rfg8 25.Nh4 Ne8 26.b5 Ka8 27.bxc6 bxc6 28.Nf3 g5
29.Rg2 h5 30.b3 Rh6 31.Kb2 Rgh8 32.Qf2 Nc7 33.Ra1 Rb8 34.Qe2 Rb7 35.Rgg1 Rh8
36.Rad1 hxg4 37.hxg4 Rc8 38.Qd3 Be6 39.Nd2 Nb5 40.Ndb1 Rbc7 41.Na4 Rb7 42.Kc1
Rcb8 43.Rg2 Rd7 44.Nbc3 Nc7 45.d5 cxd5 46.exd5 Bg8 47.Qc4 Rc8 48.Kb2 Rb8 49.e4
Rdd8 50.Rf2 Rf8 51.Rdf1 Bh7 52.Rxf6 Rxf6 53.Rxf6 Qxf6 54.Qxc7 Qh8 55.Qc6+ Rb7
56.Nb5 Kb8 57.Qxd6+ Kc8 58.Qc6+ 1-0

```

At the 24th World Championship (1961) between Botvinnik and Tal:

```
[FEN ""]
[Event "World Championship 24th"]
[Site "Moscow"]
[Date "1961.??.??"]
[Round "11"]
[White "Botvinnik, Mikhail"]
[Black "Tal, Mihail"]
[Result "1-0"]
[ECO "D14"]
[StartPly "12"]

1.d4 Nf6 2.c4 c6 3.Nc3 d5 4.cxd5 cxd5 5.Nf3 Nc6 6.Bf4 Bf5 7.e3 e6
8.Bb5 Bb4 9.Ne5 Qa5 10.Bxc6+ bxc6 11.O-O Bxc3 12.bxc3 Qxc3 13.Qc1 Qxc1 14.Rfxc1
O-O 15.f3 h6 16.Nxc6 Rfe8 17.a4 Nd7 18.Bd6 Nb6 19.Bc5 Bd3 20.Nxa7 Rxa7 21.Bxb6
Ra6 22.a5 Bc4 23.Ra3 f6 24.e4 Kf7 25.Kf2 Raa8 26.Ke3 Reb8 27.Rac3 Rc8 28.g4
Rab8 29.h4 Rc6 30.h5 Rbc8 31.e5 g6 32.hxg6+ Kxg6 33.R3c2 fxe5 34.dxe5 Rh8 35.
Rh2 Rcc8 36.Kd2 Bb3 37.a6 Bc4 38.a7 Rh7 39.Ra1 Ra8 40.Be3 Rb7 41.Rxh6+ Kg7 42.
Rah1 Rb2+ 1-0

```

And finally in 2008, between Kramnik and Anand:

```
[FEN ""]
[Event "WCh"]
[Site "Bonn GER"]
[Date "2008.10.14"]
[Round "1"]
[White "Kramnik, V"]
[Black "Anand, V"]
[Result "1/2-1/2"]
[WhiteElo "2772"]
[BlackElo "2783"]
[ECO "D14"]
[EventDate "2008.10.14"]
[StartPly "14"]

1.d4 d5 2.c4 c6 3.Nc3 Nf6 4.cxd5 cxd5 5.Bf4 Nc6 6.e3 Bf5 7.Nf3 e6 8.Qb3
Bb4 9.Bb5 O-O 10.Bxc6 Bxc3+ 11.Qxc3 Rc8 12.Ne5 Ng4 13.Nxg4 Bxg4 14.Qb4 Rxc6 15.
Qxb7 Qc8 16.Qxc8 Rfxc8 17.O-O a5 18.f3 Bf5 19.Rfe1 Bg6 20.b3 f6 21.e4 dxe4 22.
fxe4 Rd8 23.Rad1 Rc2 24.e5 fxe5 25.Bxe5 Rxa2 26.Ra1 Rxa1 27.Rxa1 Rd5 28.Rc1 Rd7
29.Rc5 Ra7 30.Rc7 Rxc7 31.Bxc7 Bc2 32.Bxa5 Bxb3 1/2-1/2

```
> 11 votes

---
Tags: history, world-championship, famous-games
---


# Question
Title: Can I use the restroom while it's my turn to play?
It's currently my turn and I *really* need to use the bathroom. I know I'm allowed to when it's my opponent's turn, but now it's not. I don't want to be accused of cheating, but I also want to play my next move with a clearer mind.

What should I do?

# Answer
> What should I do?

You should ask the arbiter for permission. Elderly men often suffer from prostate problems which increase the frequency of need to go to the toilet. If this is you then talk to the arbiter before the event and explain the situation and get permission before the need arises.

According to the FIDE Laws of Chess:

> 11.2.1 The ‘***playing venue***’ is defined as the ‘playing area’, rest rooms, ***toilets***, refreshment area, area set aside for smoking and other places as designated by the arbiter.
>
> 11.2.2 The playing area is defined as the place where the games of a competition are played.
>
> 11.2.3 ***Only with the permission of the arbiter*** can:
>
> 11.2.3.1 a player leave the playing venue,
>
> 11.2.3.2 ***the player having the move be allowed to leave the playing area***.

So, the toilets are part of the playing venue but not part of the playing area. When it is your turn you may not leave the playing area to go to the toilet without the permission of the arbiter. Or, to put it a different way, if you need to go to the toilet on your turn then first get the permission of the arbiter.
> 18 votes

---
Tags: rules, tournament, fide
---


title: How do you find FIDE rated tournaments?

text:
# Question
Title: How do you find FIDE rated tournaments?
I guess this is a more practical question. I have managed to get a FIDE ID from my country’s chess federation (ECF). but I’m not sure how exactly I’m supposed to register for FIDE-rated tournaments. I found this site, but I don’t know where I should be signing up for one of these. I appreciate any help from anyone that has experience with this.

# Answer
All FIDE rated tournaments have to be registered in advance with FIDE. How long before varies according to the type of tournament but this means that FIDE know in advance when a tournament will be and they publish this information on their website.

The general page is here. This includes a drop down box at the top which allows you to select a particular country / federation and see the upcoming tournaments in your country.

So, for instance, if I select "USA" and click "Search" I get this page which shows "Tournaments Registered for February 2022" for the USA. This confusing title means that these tournaments are registered to report their results in time for inclusion in the February rating list. This means that tournaments which are due to finish during January in time for the organiser / arbiter to submit results before the end of January will be included. Tournaments which finished in the last few days of December will also be included where there wasn't enough time for December submission.
> 2 votes

---
Tags: tournament, fide
---


# Question
Title: Does this pawn structure arising from the Caro-Kann Advance Variation have a name?
I was looking at some positions arising from the Caro-Kann Advance variation with an early c5 by black, and was wondering if this was a common structure that I could easily find model games for, or comments on the plans whether online or in a pawn structure book.

```
[FEN ""]
1. e4 c6 2. d4 d5 3. e5 c5 4. c3 Nc6 5. Nf3 cxd4 6. cxd4 Bg4 7. Be2 e6

```

From what I can tell from a few games in the database, the backwards d-pawn is often a target for black, but just wanted to read some more on this structure.

# Answer
> 7 votes
In "Chess Structures A Grandmaster Guide" by Mauricio Flores Rios he calls this structure "French Type III" Most of the examples keep the c-pawns on for a while, but there is one example with exactly the structure you describe.

Black plan is to

* target the backward d-pawn as you say
* exchange light-square bishops
* consider f6 to break up the center
* consider f5 to slow White's kingside attack

In your example with c-file open Black needs to contest the c-file as a basis for queenside play.

---
Tags: terminology, pawn-structure, caro-kann
---


# Question
Title: Full "reverse checkers" position in GM game with 12 or more pieces per player?
In yesterday's Tata Steel tournament in this game between Dubov and Artemiev this position was reached:

```
[title "Dubov - Artemiev Tata Steel 2020"]
[fen "r1r5/1p1q1pk1/2n1p1p1/2RpP2p/p2P3P/P1Q3P1/1P3P2/2R1N1K1 w - - 0 1"]

```

The position is one square/piece away from being a "reverse checkers" position with every piece for one player on one colour and every piece for the other player being on the other colour. Black's king would need to be on a white square (g8 or h7) to be a full "reverse checkers" position.

In an endgame with just a few pieces this would be an everyday occurrence but in positions where both sides have at least 12 pieces, as here, has a full "reverse checkers" position ever been achieved in a FIDE rated standard time control game between two grandmasters?

# Answer
Plenty! I ran this CQL query against Mega Database 2022:

```
// Chess Q 28034
// reverse checkers position with each side having 12+ pieces

cql()

(dark A == A and light a == a) or // white on dark squares; black on white
(light A == A and dark a == a)    // ^ vice versa
A >= 12 and a >= 12 // each side has at least 12 pieces

```

94 games were returned. Filtering those that happened between GMs:

1. Mamedyarov, Shakhriyar vs. Zelcic, Robert at the 4th European Championship on Istanbul (2003):

```
[FEN ""]
[Event "EU-ch 4th"]
[Site "Istanbul"]
[Date "2003.06.08"]
[Round "9"]
[White "Mamedyarov, Shakhriyar"]
[Black "Zelcic, Robert"]
[Result "1/2-1/2"]
[ECO "D00"]
[WhiteElo "2607"]
[BlackElo "2540"]
[PlyCount "175"]
[StartPly "54"]

1. d4 Nf6 2. Bg5 d5 3. Bxf6 exf6 4. e3 Bd6 5. c4 dxc4 6. Bxc4 O-O 7. Nc3 a6
8. Nf3 f5 9. O-O Nd7 10. a4 Nf6 11. Qb3 Qe7 12. Rfe1 c6 13.
a5 Ne4 14. Rec1 Bc7 15. Qc2 Bd7 16. Bd3 Rae8 17. g3 g6 18. Bxe4 fxe4 19. Nd2
Bf5 20. Nd5 cxd5 21. Qxc7 Qb4 22. Qc3 Qb5 23. Qb3 Qd7 24. Rc5 Be6 25. Qb6 Rc8
26. b4 Bh3 27. Rac1 Rfe8 28. f3 exf3 29. Kf2 Rxc5 30. bxc5 Bg4 31. Qb1
Bf5 32. Qb3 Bg4 33. Qb1 Bh5 34. Rc3 Re7 35. Qf1 Qa4 36. h3 Qxa5 37. Qc1 f5
38. Nxf3 Bxf3 39. Kxf3 Qb5 40. Kf2 Qc6 41. Rb3 Qd7 42. Qh1 Kg7 43. Rb6 Re6
44. Qb1 Rxb6 45. Qxb6 Kf7 46. h4 Ke7 47. Qa7 Qc8 48. Qb6 Qc6 49. Qa7 Kd7
50. Qa8 Kc7
51. Qf8 Qe6 52. Ke2 Kc6 53. Kd2 h5 54. Qb8 Qe7 55. Qg8 Kb5 56. Qxg6 Qe4 57.
Qxh5 a5 58. Qe2+ Kc6 59. Kc3 Qb1 60. Qd3 Qe1+ 61. Kb3 Qxg3 62. Ka4 Qxh4 63.
Qb5+ Kc7 64. Qb6+ Kc8 65. Qe6+ Kb8 66. Qxd5 Qf2 67. Qd8+ Ka7 68. Qxa5+ Kb8
69. Qd8+ Ka7 70. Qb6+ Ka8 71. Qb3 f4 72. exf4 Qxd4+ 73. Qb4 Qa1+ 74. Qa3 Qd1+
75. Kb5+ Kb8 76. Qe3 Kc7 77. Kc4 Qa4+ 78. Kd5 Qd7+ 79. Kc4 Qa4+ 80. Kd3 Qd1+
81. Ke4 Qh1+ 82. Kd4 Qa1+ 83. Kd5 Qa2+ 84. Ke5 Qa1+ 85. Kd5 Qa2+ 86. Ke5 Qb2+
87. Ke4 Qg2+ 88. Kf5 1/2-1/2

```
2. Gyimesi, Zoltan vs. Kovacevic, Blazimir at the Slovenian National League 2008:

```
[FEN ""]
[Event "SLO-chT 18th"]
[Site "Murska Sobota"]
[Date "2008.12.06"]
[Round "1"]
[White "Gyimesi, Zoltan"]
[Black "Kovacevic, Blazimir"]
[Result "1/2-1/2"]
[ECO "A90"]
[WhiteElo "2592"]
[BlackElo "2472"]
[PlyCount "102"]
[StartPly "75"]

1. d4 e6 2. c4 Bb4+ 3. Bd2 Bxd2+ 4. Qxd2 f5 5. g3 Nf6 6.
Bg2 O-O 7. Nc3 d6 8. f4 Qe7 9. O-O-O Nbd7 10. Nf3 Ne4 11. Qe1 Ndf6 12. e3 Bd7
13. Kb1 Rab8 14. Nxe4 Nxe4 15. Nd2 Bc6 16. Nxe4 Bxe4+ 17. Bxe4 fxe4
18. Qa5 a6 19. Rd2 c6 20. Rc1 Rbd8 21. c5 d5 22. Rc3 g5 23. Rc1 Kh8
24. Rg1 Rf7 25. Rf2 Rdf8 26. a3 Qf6 27. Ka2 Qh6 28. Qe1 Qh5 29. Kb3 Qg6
30. h4 g4 31. Qa5 Kg7 32. Ka2 Kf6 33. Rc1 Rc8 34. Rc3 Qg8 35. Rb3 Qe8
36. Rb6 h5 37. Kb1 Kf5 38. Kc1 Ra8 39. b3 Qc8 40. Rb2 Ra7
41. Qc3 a5 42. Qd2 Qa8 43. Qe2 Rc7 44. Kb1 Rc8 45. Ra2 Ra6 46. Rxa6 Qxa6
47. Qxa6 bxa6 48. Kc2 Rb8 49. Kc3 Rb5 50. Rb2 Kf6 51. b4 a4 1/2-1/2

```
3. Paragua, Mark vs. Andreikin, Dmitry at the 4th Alushta Autumn (2004):

```
[FEN ""]
[Event "Alushta Autumn 4th"]
[Site "Alushta"]
[Date "2004.10"]
[Round "8"]
[White "Paragua, Mark"]
[Black "Andreikin, Dmitry"]
[Result "1/2-1/2"]
[ECO "A48"]
[WhiteElo "2534"]
[BlackElo "2449"]
[PlyCount "110"]
[StartPly "86"]

1. d4 Nf6 2. Nf3 g6 3. Bg5 Bg7 4. Nbd2 O-O 5. e4 d6 6. c3
Qe8 7. Be2 e5 8. dxe5 dxe5 9. O-O Nbd7 10. Qc2 h6 11. Bh4 Nh5 12. Rfe1 Nf4 13.
Bf1 Nb6 14. Rad1 Be6 15. b3 g5 16. Bg3 Ng6 17. Be2 f6 18. Nf1 Rd8 19. Rxd8 Qxd8
20. Ne3 Rf7 21. c4 c5 22. Nd5 Ne7 23. b4 Nc6 24. a3 Bf8 25. Qb1 Bd6 26. Rd1 Qf8
27. Qd3 Be7 28. b5 Nd4 29. Nd2 Nc8 30. h3 Rh7 31. Bh5 Nd6 32. Nf1 Bxd5 33. exd5
e4 34. Qb1 f5 35. Be5 Bf6 36. Bxd4 Bxd4 37. Ng3 Qf6 38. Qc2 Re7 39. Ne2 Be5 40.
f3 e3 41. Rf1 b6 42. Kh1 Kg7 43. a4 f4 44. Bg4 Qg6 45. Qb3 h5 46.
Be6 Ne8 47. Rd1 Nc7 48. Bc8 Ne8 49. Kg1 Nd6 50. Be6 Qf6 51. Rf1 Re8 52. Qa2 Bc3
53. Qc2 Be5 54. Qa2 Bc3 55. Qb3 Be5 1/2-1/2

```
4. Beshukov, Sergei vs. Kryschilovskij Andrej at the 7th Chigorin memorial (1999):

```
[FEN ""]
[Event "Chigorin Memorial 07th"]
[Site "St Petersburg"]
[Date "1999.11.06"]
[Round "5"]
[White "Beshukov, Sergei"]
[Black "Kryschilovskij, Andrej"]
[Result "1/2-1/2"]
[ECO "B20"]
[WhiteElo "2506"]
[BlackElo "2343"]
[PlyCount "109"]
[StartPly "90"]

1. e4 c5 2. d3 Nc6 3. f4 g6 4. Nf3 Bg7 5. g3 e6 6. Bg2
Nge7 7. O-O O-O 8. c3 b6 9. a4 Rb8 10. Na3 d5 11. e5 a6 12. Nc2 d4 13. Ng5 f5
14. exf6 Bxf6 15. Ne4 Bg7 16. c4 h6 17. Qe2 Kh7 18. Rb1 a5 19. Bd2 Bd7 20. g4
Ng8 21. h3 Qe7 22. Ng3 Rbe8 23. Na3 Qh4 24. Be1 Qd8 25. Nb5 Qb8 26. Bd2 Nge7
27. Be4 Bf6 28. Qg2 Kg7 29. Rf3 Bh4 30. Rbf1 Kh7 31. Kh1 Nb4 32. Bc1 Na2 33.
Bd2 Nb4 34. b3 Nc2 35. Bc1 Ne3 36. Bxe3 dxe3 37. Ne2 Bxb5 38. axb5 Bf2 39. h4
Kh8 40. Qh3 Qd6 41. Kg2 e5 42. h5 g5 43. fxg5 hxg5 44. Rh1 Qh6 45. Bg6 Rd8
46. Qh2 Nxg6 47. hxg6 Qxh2+ 48. Rxh2+ Kg7 49. Rfh3 Kxg6 50. Rh6+ Kg7 51. Rh7+
Kg8 52. Rh8+ Kg7 53. R8h7+ Kg8 54. Rh8+ Kg7 55. R8h7+ 1/2-1/2

```
5. Kovacevic, Blazimir vs. Kristovic, Marijan at the 2nd Velica Gorica op (2002):

```
[FEN ""]
[Event "Velika Gorica op 2nd"]
[Site "Velika Gorica"]
[Date "2002.06.28"]
[Round "7"]
[White "Kovacevic, Blazimir"]
[Black "Kristovic, Marijan"]
[Result "1/2-1/2"]
[ECO "D03"]
[WhiteElo "2461"]
[BlackElo "2328"]
[PlyCount "97"]
[StartPly "81"]

1. d4 Nf6 2. Bg5 d5 3. e3 Nbd7 4. Nf3 e6 5. Bd3 Be7 6. c4
dxc4 7. Bxc4 a6 8. a4 b6 9. Nc3 Bb7 10. Qe2 Nd5 11. Bxd5 exd5 12. Bxe7 Qxe7 13.
a5 O-O 14. O-O f5 15. Qc2 Rac8 16. Qb3 Kh8 17. Rfe1 g5 18. Rad1 b5 19. Ne2 Rg8
20. Nd2 Rg7 21. f4 c5 22. Ng3 Rf8 23. Nf3 g4 24. Ne5 c4 25. Qc2 Qe6 26. Qc3 Kg8
27. Qb4 Nf6 28. Ne2 h5 29. Nc3 Rc8 30. Kf2 h4 31. g3 Rcc7 32. Rh1 Nh5 33. Rdg1
Qf6 34. Ke1 h3 35. Kf2 Qe6 36. Rc1 Nf6 37. Rhd1 Rc8 38. Ke2 Nd7 39. Nxd7 Rxd7
40. Kd2 Kf7 41. Re1 Re7 42. Re2 Bc6 43. Kc2 Rb7 44. Kd2 Rcc7 45. Ke1 Qe7
46. Na2 Qe4 47. Nc3 Qe7 48. Na2 Qe4 49. Nc3 1/2-1/2

```
6. Naumkin, Igor vs. Budisavljevic, Luka at the 155th Novi Sad TS Mix (2020):

```
[FEN ""]
[Event "Novi Sad TS Mix 155th"]
[Site "Novi Sad"]
[Date "2020.11.27"]
[Round "7"]
[White "Naumkin, Igor"]
[Black "Budisavljevic, Luka"]
[Result "0-1"]
[ECO "E10"]
[WhiteElo "2329"]
[BlackElo "2492"]
[PlyCount "168"]
[StartPly "119"]

1. d4 Nf6 2. c4 e6 3. Nf3 c5 4. d5 b5 5. Bg5 b4 6. Nbd2
Be7 7. Bxf6 Bxf6 8. Qc2 O-O 9. h4 exd5 10. cxd5 d6 11. e3 a5 12. Bd3 h6 13. Rd1
Bg4 14. Bh7+ Kh8 15. Bf5 Bxf5 16. Qxf5 g6 17. Qf4 Bg7 18. g4 Qe7 19. Nc4 Ra6
20. h5 g5 21. Qf5 Qd7 22. Nfd2 Qxf5 23. gxf5 Re8 24. f3 Nd7 25. Ke2 Nf6 26. Nf1
a4 27. Rd3 Kg8 28. Nfd2 Kf8 29. e4 Ng8 30. Kd1 Ne7 31. Kc1 Nc8 32. Rf1 Bf6 33.
Kc2 Na7 34. Ne3 Nb5 35. Ng4 Kg7 36. Nc4 Bd4 37. Kc1 f6 38. Rh1 Rea8 39. Rh2 a3
40. b3 Bb2+ 41. Kb1 Bc3 42. Kc2 Rc8 43. Rg2 Ra7 44. Rh2 Rcc7 45. Rg2 Ra8 46.
Rh2 Be5 47. Rg2 Kf8 48. Rf2 Ke7 49. Rg2 Rh8 50. Rf2 Kd8 51. Rg2 Ke7 52. Rf2 Ra7
53. Rg2 Ra6 54. Rf2 Nc7 55. Kd1 Ne8 56. Rf1 Bg3 57. Rg1 Bh4 58. Rh1 Ng7 59.
Nce3 Rb6 60. Nc4 Rbb8 61. Nge3 Nxh5 62. Ng2 Rbg8 63. Rh3 Ng7 64.
Nxh4 gxh4 65. Rxh4 Ne8 66. Rd2 Rg1+ 67. Kc2 Nc7 68. f4 Nb5 69. e5 Nd4+ 70. Kd3
Nf3 71. Rdh2 Nxh4 72. Rxh4 fxe5 73. fxe5 dxe5 74. d6+ Kf6 75. Ne3 h5 76. Ke4
Kg5 77. Rh2 h4 78. Kxe5 Re8+ 79. Kd5 Rxe3 80. Rd2 Kf6 81. Kc6 Re8 82. d7 Rd8
83. Kc7 Rgg8 84. Rh2 Rh8 0-1

```

Reference:

* `A` denotes any white piece, `a` any black piece.
* `dark` and `light` are used to find the count of white/black pieces that are on dark/light squares respectively.
> 6 votes

---
Tags: grandmaster, patterns
---


title: Anderssen's 'immortal game'

text:
# Question
Title: Anderssen's 'immortal game'
I came across Anderssen's 'immortal game':

```
[FEN ""]
1. e4 e5 2. f4 exf4 3. Bc4 Qh4+ 4. Kf1 b5
5. Bxb5 Nf6 6. Nf3 Qh6 7. d3 Nh5 8. Nh4 Qg5
9. Nf5 c6 10. g4 Nf6 11. Rg1 cxb5 12. h4 Qg6
13. h5 Qg5 14. Qf3 Ng8 15. Bxf4 Qf6 16. Nc3 Bc5
17. Nd5 Qxb2 18. Bd6?

```

I was curious to know whether `Bd6` is really a good move or not. StockFish 10+ does not think it is all that great. At the default depth 18 it evaluates it wrongly (strangely it gave different values whenever I forced reevaluation, but typically between -4 and -5), but even at depth 29 it still evaluates it as 0, with main line `18... Qxa1+ 19. Ke2 Qb2 20. Bxc5 Qxc2+ 21. Kf1 Qxc5 22. Qf4 Kd8 23. Nd6 f6 24. g5`.

But it seems even `18... Qxa1+ 19. Ke2 Bxg1 20. e5` is not too bad for Black, and I think continues:

```
[FEN ""]
1. e4 e5 2. f4 exf4 3. Bc4 Qh4+ 4. Kf1 b5
5. Bxb5 Nf6 6. Nf3 Qh6 7. d3 Nh5 8. Nh4 Qg5
9. Nf5 c6 10. g4 Nf6 11. Rg1 cxb5 12. h4 Qg6
13. h5 Qg5 14. Qf3 Ng8 15. Bxf4 Qf6 16. Nc3 Bc5
17. Nd5 Qxb2 18. Bd6? Qxa1+ 19. Ke2 Bxg1 20. e5 Ba6
21. Nc7+ Kd8 22. Nxa6 Qc3 23. Bc7+ Qxc7 24. Nxc7 Nc6
25. Nxa8

```

It seems Black is not really dead yet. Am I missing some subtleties?

I also noticed that the wikipedia article has an apparently inconsistent footnote \[6\], which implies that `18...Qxa1+` is better because it likely leads to `19. Ke2 Bxg1 20. e5.`, but this is precisely the same position that Anderssen reached in the actual game, which the article says led to Black's defeat...

# Answer
You are correct that 18.Bd6? is, indeed, not the best move (the simple Re1! threatens Nc7-a8 winning on material). Bd6 has widely been considered a mistake for many years now. Black holds with 18...Qxa1+ 19.Ke2 Qb2! 20.Bc5 Qc2 21.Kf1 Qc5 22.Qf4 and black has several moves that are equal, but in the last few moves, it is white that has to find the only moves along the way.

```
[fen "rnb1k1nr/p2p1ppp/3B4/1pbN1N1P/4P1P1/3P1Q2/PqP5/R4KR1 b - - 0 1"]

1...Qxa1+ 2.Ke2 Qb2! 3.Bc5 Qc2 4.Kf1 Qc5 5.Qf4

```

Of course, this was played at a time where "romantic chess" was still at its peak, and winning practically was not their mindset. It was sacrifice, and if your opponent offered pieces, you took them.

Lastly, with computers getting stronger every year, who knows, maybe 18...Qa1 will eventually still be found to be winning for white, but that is a moot point since Re1 kept the material and the attack.
> 3 votes

# Answer
18.Bd6 is indeed winning. All of the suggested refutations simply delay the inevitable loss for black and the coordination of the bishops and knights is stunning.

Let's look at the possible refutation, 18. ...Qxa1 19. Ke2 Qb2

20.Kd2 is the only winning move here. It keeps the king in safety and maintains that white has a winning attack.

Black must accept the sacrificed rook with 20. ...Bxg1. The only other reasonable move, 20. ...Bb6, loses quickly to 21.Bb4! Kd8 22. h6.

In any case, white plays 21. e5, with an idea similar to Andersson's. 21. ...Bb7 is losing to 22. Nxg7+, and 22. Ba6 loses to 22. Bb4!, leaving black in Zugzwang. Just a brutal suffocation of black from that dominant white bishop and two knights.
> 0 votes

# Answer
I would rather not even play 17.Nd5, but go 17.d4!, kicking the bishop back, and then continued with Nd5. If Anderssen planned on sacrificing, he has already made it clear by the previous move (Nd5 -\> Bd6). Holding back after the sacrifice on b2 would be illogical.
> 0 votes

---
Tags: analysis, theory, sacrifice, master-games
---


# Question
Title: How does the Najdorf variation of the Sicilian defense stop the Keres attack?
Recently I've been looking into the Scheveningen variation of the Sicilian and from what I have read it seems like the Keres attack is a big threat and you need great calculation ability to stop it as Black. This is why numerous books have recommended just playing the Najdorf and then e6 on the 6th move saying that the Najdorf (a6) stops the Keres attack.

My question is how the move a6 stops the Keres attack. If I could have a specific game or something since I can't find a concrete answer anywhere else.

# Answer
In the Najdorf variation (1.e4 c5 2.Nf3 d6 3.d4 cd4 4.Nxd4 Nf6 5.Nc3 a6), the c8-h3 diagonal remains open and Black has two hits (Nf6, Bc8) on the square g4. If White plays 6.g4?? in the spirit of the Keres attack, Black already gets a decisive advantage with 6...Bxg4, grabing a free pawn with tempo.

In contrast, the Keres variation 6.g4!? is possible against the Scheveningen because 5...e6 (or 2...e6 is Black chose another move order) blocked the Bc8 diagonal and reduced their control of g4: then 6...Nxg4?? 7.Qxg4 e5 8.Nf5 g6 9.Bc4 would be winning for White.

*Edit Feb 2022* : In spite of the loss of a pawn, some players are toying with the idea of playing 6.g4? against the Najdorf anyway. World Blitz Champion Maxime Vachier-Lagrave used it in a demo bullet game against GM Bilel Bellahcene, live on French TV. Bellahcene quips: "hey, you're using my own variation!"
> 9 votes

# Answer
If Black actually plans to play e6 after a6 anyways, White can play 6. Be3 e6 7.g4. Apart from normally looking h6, Black can respond with 7...e5, and since White cannot exchange the threatening bishop with Bb5+ and is ahead in development, decides to sacrifice the knight with 8. Nf5 g6, leading to Hungarian attack https://en.wikipedia.org/wiki/Sicilian\_Defence,\_Najdorf\_Variation#English\_Attack:\_6.Be3 . From what I remember, it has not been refuted yet.
> 0 votes

---
Tags: sicilian-defense
---


title: How do you register a FIDE rating?

text:
# Question
Title: How do you register a FIDE rating?
I want to register a FIDE rating, but I can find nothing about that on the official website. How do I register an official FIDE rating?

# Answer
> 30 votes
> how do I register an official FIDE rating?

You don't register a FIDE rating because you have no authority to assign yourself a FIDE rating. Only FIDE can do that.

What you need to do is play in one or more FIDE rated tournaments where you:

1. Play at least 5 games against players who already have a FIDE rating
2. Score at least half a point against them
3. Get a rating of at least 1000

In that case in the month after the tournament organisers submit the results of their tournaments to FIDE for rating then you will get a FIDE rating. Actually the regulations say that the results must be submitted at least 3 days before the end of the month but my experience is that FIDE are more efficient than that and often results submitted two days before still get in to the next list.

The latest FIDE rating regulations are here.

---
Tags: rating, fide
---


# Question
Title: Approximating a rating for too strong engines
Suppose we have an extremely strong engine that happens to win every game it participates in even against the most powerful engines and players. If it continues to win every game, its rating (for example ELO) will grow indefinitely. But we do not have an infinite amount of time, so we will have to stop evaluating sometimes with some rating R. On the other hand, it feels wrong to stop at rating R because it is likely our engine will win its next game and get a rating R' \> R. Moreover, we cannot give this engine a rating of infinity, because in theory it can draw or lose, it just hasn't yet faced such an opponent.

How would you find a rating approximation for such an engine?

# Answer
> 7 votes
I'd treat this as a Bayesian inverse probability problem. Per Laplace's rule-of-succession solution of the sunrise problem (see https://en.wikipedia.org/wiki/Rule\_of\_succession and https://en.wikipedia.org/wiki/Sunrise\_problem), it follows that **if an engine wins *n* out of *n* games, its rating should be estimated as if it played *n+3* games, winning *n+1*, drawing one, and losing one** \- playing, of course, against the same pool of opponents. (A point of note: a chess game differs from a sunrise in that there are *three* possible outcomes, rather than just two. For the sake of simplicity, we'll assume the number of games with black and white pieces is equal.)

Using the example provided above, the rule-of-succession method returns an estimate of 2230 (1000 games), 3330 (1M games), and 3450 (2M games) - not that far off from Bayeselo. I'm not familiar with the method employed by Bayeselo and cannot say how mathematically sound it is, but in the end this is a kind of problem that doesn't have a "correct" solution because it hinges on one's choice of prior probability. In Laplace's approach, it is posited that, if we knew nothing about the history of sunrises, we should assume that the probability of Sun rising tomorrow is uniformly distributed between 0 and 1. Whether that assumption is applicable to a chess game between two players about whom we know nothing is anyone's guess.

(Additional note: I'm assuming here that the question is how to estimate Elo once *n* games have already been played, rather than when to stop playing more games. The answer to the latter question is significantly more complex as it obviously depends on additional factors.)

# Answer
> 11 votes
There're a few ways to do it:

* Add 400 rating to the top opponent and take that as an approximation (used by USCF)
* Add a draw for the engine against itself
* Assign an infinite rating
* Use linear approximation

By the way "win every game against the most powerful engines and players" is realistically not happening, because chess is a draw\** and top engines on strong hardware guided by a human are already so close to perfect play that the great majority of all correspondence chess games are drawn.

\**It's not proven that chess is a draw, but you won't find any top player seriously disagreeing with this assessment. See also this answer illustrating what things are like at the top level of play (world correspondence chess championship, which is stronger than both engines and humans alone).

# Answer
> 2 votes
While there will be no concrete answer to this, there are few methods of approximation. We can play it against a 7 man tablebase, and for the sake of ELO rating we can assume that its strength in the middlegame or the opening is the same as the endgame. The number of losses that an endgame tablebase delivers to it (giving the borderline winning side to the tablebase and a blessed loss to the engine) determines its strength.

Another method we can use is the number of moves it takes to defeat the opposing engine. While not always correct, the general rule is that the more moves it takes to defeat the opponent, the weaker the player.

# Answer
> 2 votes
According to bayeselo program if the best wins 1k games without loses and draws and setting the opponent rating to 1000, it will get 2092.

```
Rank Name:   Elo    +    - games score oppo. draws   win  loss  draw
   1 best:  2092  170   83  1000  100%  1000    0%  1000     0     0
   2 p1  :  1000   83  170  1000    0%  2092    0%     0  1000     0

```

1M games:

```
Rank Name:   Elo    +    - games score oppo. draws   win  loss  draw
   1 best:  3203  167   82 1e+06  100%  1000    0% 1e+06     0     0
   2 p1  :  1000   82  167 1e+06    0%  3203    0%     0 1e+06     0

```

2M games:

```
Rank Name:   Elo    +    - games score oppo. draws   win  loss  draw
   1 best:  3314  161   83 2e+06  100%  1000    0% 2e+06     0     0
   2 p1  :  1000   83  161 2e+06    0%  3314    0%     0 2e+06     0

```

# Answer
> 0 votes
You could let the engine play with a handicap (e.g. rook down).

Then, you need to calibrate how much rating delta a missing rook means. I saw some numbers that estimated one point of material to be a delta of 100 points.

This calibration could be done through self-play. Let the engine play against itself and see how much a rook is worth.

A downside of this handicap method is that it changes the game dynamics. Engines are not optimized for starting the game in an unusual position with a massive disadvantage. This can throw off some heuristics.

---
Tags: engines, rating, mathematics
---


# Question
Title: Moving absolutely pinned piece to give checkmate: has this ever occured in a master game?
We know that an absolutely pinned piece (a piece pinned against its own king) can move and give a check, and the check can even be a mate.

The following is an example of such a checkmate.

```
[FEN "8/8/2k5/8/4p2b/r7/3RKPBr/q7 w - - 0 1"]

1. f4 exf3#

```

Source: A. Skodras, Quora

**I am interested in knowing whether this has ever occurred in a master game**; say, both opponents are rated 2000+ and the game was competitive (e.g. in a tournament).

Note: To be clear, I would like to exclude the case of a pinned piece capturing the pinning piece and checkmating the opponent king at the same time (unless it is still in absolute pin). Thanks to Evargalo for pointing this out.

I suppose this happening in a game would be rare, let alone in a master game. But, the first impression (I had) that "moving a pinned piece and giving check cannont be a good move" is wrong.

```
[Title "Schatz vs. Giegold, Hof (1928)"]
[FEN "7k/pb5q/1p3p2/2p1p1p1/6P1/QP4KR/P4PP1/1B5r b - - 0 1"]

1... Qh4+

```

Source: Martin Weteschnik, Understanding Chess Tactics (btw, this is one of the best books on how tactics work).

Here, the move 1... Qh4+ is the best move (along with 1... Rxh3+ which is a slightly slower mate).

## Addendum

CQL may be the best solution for questions of this type. One way I can think of to form a CQL query is the following (and its `flipcolor` variant):

1. white gives check (and mates black) in the current position,
2. the piece last moved is X,
3. if piece X is removed from the previous position, then white is in check.

I don't know how (or whether) step 3 can be expressed in CQL.

# Answer
> 8 votes
I used this CQL query to find such positions:

```
cql(input Mega_Database_2022.pgn)

flipcolor {
    pinningPieces = pin from A
    pinnedPieces = pin through a

    line --> pin from A
         --> {
                 wtm
                 mate
                 pin from A == pinningPieces
                 pin through a != pinnedPieces
             }
}

```
* `flipcolor`: check if a position meets the criteria for the given colours, then reverse them.
* `pin from A`: a white piece (`A`) pins the black king. `from` is the first argument, therefore the squares of the pinning pieces are returned. These *shouldn't* change - they aren't moved.
* `pin through a`: a black piece (`a`) is pinned against its own king. `through` is the first argument, therefore the squares of the pinned pieces are returned. These *should* change - one moved to mate the other side.
* `wtm mate`: white has been mated.
* `line --> a --> b`: the current position should match filter `a` and the position after the next move should math filter `b`.

Running the script against Mega Database 2022 only returns 9 (!) games. All follow the same pattern: a pawn is "pinned" by a major piece and moves to give checkmate.

Only 2 are master games:

1. Rocha, Wellington Carlos vs. Braga, Cicero Nogueira at the Paulisto Championship (1999):

```
[FEN ""]
[Event "Paulisto-ch final"]
[Site "Americana"]
[Date "1999"]
[Round "5"]
[White "Rocha, Wellington Carlos"]
[Black "Braga, Cicero Nogueira"]
[Result "1-0"]
[ECO "B23"]
[WhiteElo "2361"]
[BlackElo "2405"]
[PlyCount "81"]
[StartPly "80"]

1. e4 c5 2. Nc3 Nc6 3. f4 g6 4. Nf3 Bg7 5. Bc4 e6 6. O-O Nge7
7. d3 d5 8. Bb3 O-O 9. Qe1 Na5 10. exd5 Nxb3 11. axb3 exd5 12. Qf2 d4
13. Ne4 b6 14. Bd2 Nd5 15. Rfe1 h6 16. Ne5 Kh7 17. Qf3 f5 18. Nf2 Bb7
19. c4 dxc3 20. bxc3 Qc7 21. Qg3 Ne7 22. h4 Bf6 23. Nh3 Rg8 24. Re2 Rg7
25. Rae1 Rd8 26.Nf2 Ba8 27. Nf3 Nd5 28. Ng5+ hxg5 29. hxg5 Be7 30. c4 Nb4
31. Bc3 Rd4 32. Bxd4 cxd4 33. Qh3+ Kg8 34. g4 Qb7 35. gxf5 gxf5 36. Ne4 Nxd3
37. Nf6+ Bxf6 38. Re8+ Kf7 39. Qh5+ Rg6 40. Qh7+ Rg7 41. g6# 1-0

```
2. Petrosyan, Manuel vs. Vachier Lagrave, Maxime at a Titled Tuesday blitz on chess.com (2020)

```
[FEN ""]
[Event "Titled Tuesday intern op 9th June"]
[Site "Chess.com INT"]
[Date "2020.06.09"]
[Round "4"]
[White "Petrosyan, Manuel"]
[Black "Vachier Lagrave, Maxime"]
[Result "0-1"]
[ECO "D12"]
[WhiteElo "2607"]
[BlackElo "2778"]
[PlyCount "96"]
[EventDate "2020.06.09"]
[StartPly "95"]

1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. e3 Bf5 5. Nc3 e6 6. Nh4 Be4
7. f3 Bg6 8. Qb3 Qc7 9. Bd2 Be7 10. Rc1 Nbd7 11. g3 dxc4 12. Bxc4 a6 13. a4
O-O 14. Nxg6 hxg6 15. O-O b5 16. Be2 Qb6 17. Ne4 Rfc8 18. Rc2 Nxe4 19. fxe4 b4
20. Rfc1 Qb7 21. e5 c5 22. Kf2 Rab8 23. Bf3 Qa7 24. Qd3 Rd8 25. Qe4 Qb6 26. b3
a5 27. h4 cxd4 28. exd4 Nf8 29. Be3 Rd7 30. d5 exd5 31. Qxd5 Qd8 32. Qc4 Ne6
33. Bg4 Rd5 34. Bxe6 fxe6 35. Qg4 Rxe5 36. Bf4 Rf5 37. Qxg6 Qd5 38. Rc8+ Rxc8
39. Rxc8+ Bf8 40. Kg1 Qxb3 41. Re8 Rf6 42. Qg4 Qb1+ 43. Kh2 Qe4 44. Qg5 b3 45.
Bd6 Qe2+ 46. Kh3 Qf1+ 47. Kg4 Qf5+ 48. Kh5 g6# 0-1

```

Reference (from CQL documentation):

Download CQL for Windows and Mac along with some examples from the official website. Email the authors for the Linux distribution.

---
Tags: checkmate, master-games, pins, cql
---


# Question
Title: Evaluation bar cheating - how much does it really give, and how can it be detected?
To start off - due to my anxiety, I do not play any form of chess against other people (except some friends of mine, but that obviously doesn't matter for the context of this post).

I recently got really interested in how cheating in chess operates and how it's detected. Specifically, this post gave me a lot of ideas how cheating is detected in general.

However, I have been wondering about the following scenario: let's imagine somebody is playing online chess, and they can see the evaluation bar in real time, with no additional information. For example, after blundering a piece, the player would immediately see that his opponent is better off. The same would be true the other way around - the player could see that his opponent made a mistake immediately, but without knowing what mistake that was exactly, without seeing any engine moves or possible threats.

So now my questions are:

1. How would something like this even be detected? Especially at lower rating, since the player would probably not be able to interpret the results correctly (most of the time anyway).
2. How much of an advantage would this really give? I assume for lower-rated players this would barely do anything, but for more skilled players, would this really be a lot?
3. How much would the time control affect the impact of this? Would fast chess benefit less than classical?

Do you know / have you heard about this method being used by players? Any insights are welcome, as this is a question asked out of pure curiousity.

# Answer
> 11 votes
For 1):

1. The player that uses an eval bar will successfully capitalize on opponents' mistakes more often than the player that does not, playing like a higher-rated player in this regard. However, they will not make fewer losing mistakes than a player at their true strength.
2. The player will almost always spend more time thinking about a move following an opponent's blunder, no matter how complicated the tactic they blundered is.

A chess platform could perform some statistical test that reflects either effect (for example, 1 may affect the distribution of the player's "game shapes" on chess.com), and the player would be found as an outlier and examined further.

# Answer
> 4 votes
> I assume for lower-rated players this would barely do anything, but for more skilled players, would this really be a lot?

I would expect it to be the opposite. Very low Elo players often hang a piece for several turns, with neither players noticing it. If a player sees the eval bar suddenly move several points, they can look for a hanging piece, available fork, etc. For higher ranked players, larger swings in eval are rarer, and at really high levels, if an engine says someone made a blunder, there's a significant chance it's wrong. Now, if a high ranked player could, for each move, make one tentative move and see the resulting eval before committing to the move, that could be very valuable, as they could identify a safe move and a risky move, and fall back on the safe move if the risky move turns out to not be sound.

# Answer
> 4 votes
This kind of cheating provides a big (150-200, maybe more) elo advantage, according to a GM I asked.

Check out this position:

```
[FEN "5k2/8/5pK1/3B1P1P/3n4/8/3b4/8 w - - 0 1"]

```

(Black to play)

This position is from Carlsen-Caruana, World Chess Championship 2018, game 6. Before consulting an engine, how would you evaluate the position?

I suspect most humans would feel the game is drawn. Black can try, but it's hard to dislodge White from the corner. However, turn on an engine and you'll see that Black has a forced mate in 30. The line is deep enough that Kasparov wrote no human could've found it.

Or could they? Caruana's second, Rustam Kasimdzhanov, makes a telling observation:

> "Maybe the move was indeed difficult to see. **But it was not impossible. However, to find such a move you have to believe that you can win this endgame.** And even if it is objectively drawn you can still try some tricks"

Based on the highlighted text, if Caruana did know Black has a mate in 30, my money is on Caruana finding the win. Here is another "missed" win of this kind; if Ding Liren had access to the engine eval I would also bet on him finding the win.

In the same way, if someone shows you a position (puzzle) and tells you "White to move and win", it becomes easier to solve. If they just asked you for what you think of the position, it's much harder. If you know there is a win (or if you know there is a defense), you look until you find it.

As for detecting such cheating, I have not seen any sources on how it might be done. I imagine most of it would come from time management: the cheater thinks hard and finds obscure wins or defenses that most other humans would not have found.

# Answer
> 1 votes
Further to Edward's answer, suppose that a weakness of the player is that they are poor at spotting sound combinations that start with sacrifices. They might see BxP+ but reject it because it loses bishop for pawn, without seeing the longer-term advantage of a sound attack over the next few moves. Then their knowledge of the eval bar might encourage them to make such sacrifices -- if the eval bar goes down, they know to cut their losses; otherwise, that encourages them to go ahead and continue the attack so long as the eval doesn't go down. The eval bar has given them a dishonest proxy for long-range vision.

# Answer
> 1 votes
> How much of an advantage would this really give? I assume for lower-rated players this would barely do anything, but for more skilled players, would this really be a lot?

Knowing the score is a **huge** advantage in an online chess game. You can adjust your strategy based on the score. This is like inside stock trading.

> How would something like this even be detected? Especially at lower rating, since the player would probably not be able to interpret the results correctly (most of the time anyway).

As I mentioned in the other post, as soon as you use the information for your advantage, you will statistically perform better than everybody else in your rating group.

---
Tags: engines, cheating
---


# Question
Title: Is it possible to know an average variability of score on chess.com?
If I play a number of 10 minute games on an "off day", on chess.com, my score can plummet by 100 points. Conversely, if I'm well-slept, just had some good news (no stress), fresh breakfast and coffee, I can win game after game, raising my score by 100+

I used to think a person's score was a fair indicator of skill level and therefore what I was "up against", but now I'm thinking not so much. I've played high score players making repeated blunders, and low score players whipping me.

Is there any data on the average variability or score bracket that players have?

For example, if I play a person with score 900, are they more likely to be bracketed 875-925, or maybe 850-950, or even 800-1000 ?

# Answer
chess.com uses the Glicko rating system. The rating has an associated RD (rating deviation). If RD is low, the rating is more reliable or accurate.

Consider the rating info of Magnus at present.

```
{'chess_blitz': {'best': {'date': 1607707714,
                          'game': 'https://www.chess.com/game/live/5942875338',
                          'rating': 3192},
                 'last': {'date': 1607716342, 'rating': 3123, 'rd': 53},
                 'record': {'draw': 52, 'loss': 32, 'win': 137}},
 'chess_bullet': {'best': {'date': 1604349635,
                           'game': 'https://www.chess.com/game/live/5878212456',
                           'rating': 3350},
                  'last': {'date': 1607718902, 'rating': 3260, 'rd': 68},
                  'record': {'draw': 11, 'loss': 19, 'win': 59}},
 'chess_rapid': {'best': {'date': 1418582233,
                          'game': 'https://www.chess.com/game/live/7498870151',
                          'rating': 2862},
                 'last': {'date': 1613844867, 'rating': 2810, 'rd': 241},
                 'record': {'draw': 1, 'loss': 0, 'win': 5}},
 'fide': 2882,
 'lessons': {},
 'puzzle_rush': {},
 'tactics': {}}

```

He has a blitz rating info of:

```
'last': {'date': 1607716342, 'rating': 3123, 'rd': 53},

```

The rd is 53. The rating interval is:

```
min_rating = 3123 - 53*2 = 3017
max_rating = 3123 + 53*2 = 3229

```

So in a bad day he might play at lower end of the rating which is 3017 and in a good day he might play at a higher end of the rating which is 3229.

Different players may have different RD. If the number of games played by a player is low, the RD will be high and the rating range from `max_rating - min_rating` will be high too. If this range is high the accuracy of the rating is lower.
> 3 votes

# Answer
Rating does of course say something about your strength, but I once saw someone of about 1375 absolutely wiping out 1800’s. Rating says something, but other factors such as underestimation, luck, and your mood also play a role.
> 2 votes

---
Tags: chess.com
---


title: Famous pawn promotion matches

text:
# Question
Title: Famous pawn promotion matches
Except for a famous match between Tigran Petrosian and Bobby fischer, I don't know of any famous chess match between top notch players which had some climactic pawn promotions . Could anyone here suggest a few more of matches of that kind?

# Answer
A game between McDonnell and De La Bourdonnais is very famous. Although no promotion was executed on the board, it is definitely the theme of the game.

```

      [FEN ""]
      [Event "London m4 ;HCL 18"]
      [Site "16"]
      [Date "1834.??.??"]
      [EventDate "?"]
      [Round "62"]
      [Result "0-1"]
      [White "Alexander McDonnell"]
      [Black "Louis Charles Mahe De La Bourdonnais"]
      [ECO "B32"]
      [WhiteElo "?"]
      [BlackElo "?"]
      [PlyCount "74"]
      [StartPly "74"]

1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 e5 5.Nxc6 bxc6 6.Bc4 Nf6
7.Bg5 Be7 8.Qe2 d5 9.Bxf6 Bxf6 10.Bb3 O-O 11.O-O a5 12.exd5
cxd5 13.Rd1 d4 14.c4 Qb6 15.Bc2 Bb7 16.Nd2 Rae8 17.Ne4 Bd8
18.c5 Qc6 19.f3 Be7 20.Rac1 f5 21.Qc4+ Kh8 22.Ba4 Qh6 23.Bxe8
fxe4 24.c6 exf3 25.Rc2 Qe3+ 26.Kh1 Bc8 27.Bd7 f2 28.Rf1 d3
29.Rc3 Bxd7 30.cxd7 e4 31.Qc8 Bd8 32.Qc4 Qe1 33.Rc1 d2 34.Qc5
Rg8 35.Rd1 e3 36.Qc3 Qxd1 37.Rxd1 e2 0-1

```
> 10 votes

# Answer
There is also a famous miniature between Spassky and Larsen, that ends with a pawn promotion:

```

      [FEN ""]
[Event "USSR vs. Rest of the World"]
[Site "Belgrade SRB"]
[Date "1970.03.31"]
[EventDate "1970.03.29"]
[Round "2.1"]
[Result "0-1"]
[White "Bent Larsen"]
[Black "Boris Spassky"]
[ECO "A01"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "34"]

1. b3 e5 2. Bb2 Nc6 3. c4 Nf6 4. Nf3 e4 5. Nd4 Bc5 6. Nxc6
dxc6 7. e3 Bf5 8. Qc2 Qe7 9. Be2 O-O-O 10. f4 Ng4 11. g3 h5
12. h3 h4 13. hxg4 hxg3 14. Rg1 Rh1 15. Rxh1 g2 16. Rf1 Qh4+
17. Kd1 gxf1=Q+ 0-1

```
> 3 votes

# Answer
One famous game is the one in which Alekhine sacrificed three queens. I pulled the moves from chessgames.com

```
[Title "Efim Bogoljubov-Alexander Alekhine, Hastings, Hastings England, 9/22/1922"]
[FEN ""]

1. d4 f5 2. c4 Nf6 3. g3 e6 4. Bg2 Bb4+ 5. Bd2 Bxd2+ 6. Nxd2 Nc6 7. Ngf3 O-O 8. O-O d6 9. Qb3 Kh8 10. Qc3 e5 11. e3 a5 12. b3 Qe8 13. a3 Qh5 14. h4 Ng4 15. Ng5 Bd7 16. f3 Nf6 17. f4 e4 18. Rfd1 h6 19. Nh3 d5 20. Nf1 Ne7 21. a4 Nc6 22. Rd2 Nb4 23. Bh1 Qe8 24. Rg2 dxc4 25. bxc4 Bxa4 26.Nf2 Bd7 27. Nd2 b5 28. Nd1 Nd3 29. Rxa5 b4 30. Rxa8 bxc3 31. Rxe8 c2 32. Rxf8+ Kh7 33. Nf2 c1=Q+ 34. Nf1 Ne1 35. Rh2 Qxc4 36. Rb8 Bb5 37. Rxb5 Qxb5 38. g4 Nf3+ 39. Bxf3 exf3 40. gxf5 Qe2 41. d5 Kg8 42. h5 Kh7 43. e4 Nxe4 44. Nxe4 Qxe4 45. d6 cxd6 46. f6 gxf6 47. Rd2 Qe2 48. Rxe2 fxe2 49. Kf2 exf1=Q+ 50. Kxf1 Kg7 51. Ke2 Kf7 52. Ke3 Ke6 53. Ke4 d5+ 0-1

```
> 3 votes

---
Tags: pawn-promotion, pawn-endgame, famous-games
---


# Question
Title: Average number of moves until checkmate for two players of unequal strenth
Suppose a game is played, until checkmate, between players of unequal strength, say 1800 vs 2800. What would be the average number of moves be for, say, 1000 games? I also ponder 2000 vs 2800 and 2200 vs 2800? for any time control.

I was thinking to pitch two computer engines, but I could not find any computer vs computer online. Then I tried myself (1750) vs Stockfish level 20. On the 5th attempt, I lasted 40 moves, much longer than Iexpected.

Edit: Edward: Good point, likely knowing I can't win vs machine I was just exchanging all the way, don't remember any more. DM: I was thinking checkmate, as different players will resign at different times. There is question on this site, "Can you resign if your opponent has only king?". Apparently - yes?! Mike Jones: This would be good test likely, though I'm not sure with such discrepancy in rating how many games are there. And I'm not in possession of any. Thank you all.

# Answer
> 2 votes
Tried to run it with engines from CCRL blitz rating list using common 16 opening positions without adjudications. Each opening is played twice such that each engine handles both white and black side from the start of the game.

The games are played at TC 1min + 1sec inc.

The result is as expected, as the rating of the opposition increases the number of plycount also increases - showing resistance.

The plycount in a game is the total number of moves played by each player. The movecount is approximately equal to plycount/2.

We can also infer that as we increase the TC the resistance also increases.

#### Results

```
           mean_plycount  games
cat
2800_1800             85     32
2800_2000            100     32
2800_2200            118     32

```

#### Engines

```
           engine  ccrl_blitz_rating
0  Rhetoric 1.4.3               2806
1     CDrill 1800               1806
2   Requiem v0.53               2009
3     CT800 V1.31               2205

```

#### Openings

```
0             King's Indian
1         Caro-Kann defence
2        Alekhine's defence
3                      Reti
4   Nimzovich-Larsen attack
5                  Sicilian
6            Benoni defence
7                  QGD Slav
8              Pirc defence
9         Gruenfeld defence
10   Queen's Indian defence
11                  English
12                      QGD
13                Ruy Lopez
14             Giuoco Piano
15           French defence

```

---
Tags: engines, software, checkmate, statistics, computer-chess
---


title: Insufficient material rule

text:
# Question
Title: Insufficient material rule
As I understand chess rules, *insufficient material* means *K vs. K*, *K vs. KB*, or *K vs. KN*. (Correct me if I am wrong.)

But what about *KB vs. KB* when both bishops are in the same colored square? Am I right that that kind of position also will end up with a draw even if one player makes inaccurate moves?

Also, theoretically, there is a way to get position *K vs. KBB* where both bishops are in the same colored squares (if you promote your pawn to the bishop). Can this position also include to that rule?

What other theoretical positions may there be, which are 100% draws?

I ask this question as a programmer, not as a chess player, and the main purpose of this topic is to "teach" computers to understand the *insufficient material* rule.

# Answer
> As I understand chess rules insufficient material means K vs. K, K vs. KB, or K vs. KN.(Correct me if I am wrong)

Your understanding is wrong. the FIDE Laws of Chess have no "insufficient material" rule. What they do have is basically a "no helpmate" rule. Such a position is called a "dead position". That is to say that if there is no possible helpmate then the position is a draw. This is how it is phrased in article 5.2.2:

> 5.2.2 The game is drawn when a position has arisen in which neither player can checkmate the opponent’s king with any series of legal moves. The game is said to end in a ‘dead position’. This immediately ends the game, provided that the move producing the position was in accordance with Article 3 and Articles 4.2 – 4.7.

> But what about KB vs. KB?

The rule you have to follow is that if you can place the pieces on the board in such a way that it is checkmate and you can move the pieces from their original positions when you have to make the decision to the checkmate position using only legal moves then it is not a draw.

So, for KB vs. KB where the bishops are the same colour you can quickly see that there is no possible checkmate position and it is a draw. Same for king plus any number of same squared bishops versus king plus bishop of the same colour.
> 10 votes

# Answer
KB vs KB when both bishops are of the same color it is automatically declared draw by insufficient material. The same with KBB vs KBBB (theoretically possible), as long as all bishops move on OR white squares OR all of them on black squares. If just one bishop moves on a different color, someone can still win.
> 2 votes

---
Tags: rules, endgame, fide, draw
---


# Question
Title: What does "hashfull 1000" mean in Stockfish?
When I use Stockfish, the "hashfull" value climbs up to 1000 and then stays there. I was wondering what this means.

The documentation says :

`* hashfull <x> the hash is x permill full, the engine should send this info regularly`

But this doesn't help me to understand what it means.

# Answer
> 4 votes
An engine's hash table is a data structure where the engine stores positions and evaluations which it already calculated.

The parameter *hashfull* tells what permille full the hash is, i.e. how full it is on a scale of 0-1000. Hashfull 0 means that the hash is empty, no data is being stored. Hashfull 1000 means that the hash is full, and no more data can be stored.

If the hash is always full, then the engine could perform better with a larger hash (if you have more memory available for this)

---
Tags: engines, stockfish, programming
---


# Question
Title: How to improve at calculation and visualisation?
My Lichess rapid rating is around 2100 and I'm quickly realising how poor my visualisation skills are, causing my calculation to be horrible even just two or three moves deep. I have worked on The Woodpecker Method for a while on Chessable and am going pretty well, and generally find tactics pretty quickly in my games, so I think my tactical pattern recognition is fine, but my raw calculation skills are very bad as a consequence of poor visualisation.

Most similar questions on this site are answered from a pattern recognition perspective which isn't really what I'm going for; I'm wanting to calculate variations from a complex middlegame position, not solve tactics. And just pulling up master games and trying to calculate variations from the middlegame to practice doesn't get me very far, since I just get so foggy a few moves in. I very quickly mix up pieces that have moved in my variation with pieces that are still on the board.

Has anyone realised their visualisation was terrible at a similar level, and managed to improve it? How could I do this?

A side note: I have heard of aphantasia, but I don't think that's the problem. I can picture things in a general foggy way that I'm assuming is normal.

# Answer
> 4 votes
You might like to check out medicine.exeter.ac.uk/research/neuroscience/theeyesmind to see exactly how your visualizing capabilities compare with others. You say that you "can picture things in a general foggy way that I'm assuming is normal." but you may find that you are well below average (for a few people the picture in their head is the same as normal sight). In that case you will have to adjust to this situation, and advice about how to use good visualization will have little value. Even if so, your situation is far from hopeless.

I am myself extremely aphantasic. I see no mental images (and do not imagine any other sensory experiences) which puts me in less than 1% of the population. But my best rating (many years ago now) was 207 on the old British Chess Federation system. Roughly equivalent to 2300 FIDE and maybe 2600 Lichess (If you check, you will see that I have fallen far) I have played blindfold well enough to beat a weak player. Strong visualisers find this hard to believe.

I can see a great deal from the current position and forecast quite far into the future without in any way seeing the future. Questions such as

Where are my and my opponents weaknesses?

Are my pieces harmonious (Supporting each other but free to move)?

What is the balance of attackers and defenders for some vulnerable piece or square?

Which pieces do I want to exchange?

Where should I direct my attack?

do not (at least for me) require any visualization. Neither do short combinations. I know where the pieces will go without having to see them. I do occasionally mess up. At the end of a combination I have to ask, is that mate? I check each square around the King and ask which of my pieces is covering it or which of my oppenents pieces is blocking it. I can do this by recalling which moves each piece has made, but sometimes I forget.

In the immediate position I do not have much difficulty "seeing" possible moves that are enabled by a pin, or by a fork on the following move. There is a difference here between seeing and perceiving.

My advice to the OP is as follows. First establish how (ab)normal your visualizing ability is, Many people do not discover until quite late in life that they are different. If you do discover that you have aphantasis, it is a permanent condition and there is very little you can do about it. Ignore all the advice about how to play blindfold. Concentrate on what you can perceive in the position before you. Ask the questions that I suggest but make up your own. How much can you make use of what you CAN see?

# Answer
> 3 votes
Mixing up your visualization with what is on the board is a standard type of error. Not looking at the board while calculating may help.

I do not think there is a normal in the general public of how thinking works. For example, some people never visualize at all, called "aphantasia " as you say. I don't know if people like that play chess. There are degrees of visualization. Do you normally visualize when thinking about anything? Do you only visualize when explicitly deciding to or does it just happen? It may be that this method of thinking isn't your way.

How is not visualizing well a problem for your chess? I mean are you working on it because it is causing issues in your games or because visualization exercises are a standard recommendation? If you have specific chess problem perhaps there is a non-visual way to improve them.

One thing I do when trying to calculate past fog is to stop and fix a position in my mind. When I have it solidly I calculate from there. When I say solidly I mean not foggy at all.

---
Tags: learning, visualization
---


# Question
Title: Why wasn't Ne5 a mistake when I could just win the exchange in one move?
I had this position arise in a game:

```
[FEN "4qrk1/3rppbp/1p4p1/p2P4/1pBP1B2/1P2PN2/5PPP/R2Q1RK1 w - - 2 21"]
[White "Kevin"]
[Black "lichess AI level 3"]

1. Ne5 {I advance a knight and, incidentally, attack the rook. In retrospect, this move looks just plain wrong to me, because Bb5 is better, but Stockfish says it's OK.} (1. Bb5 {White wins a rook for a bishop immediately and Black has no obvious counterplay aside from trying to win the pawn on d5. This is the best move according to Stockfish.}) Rc7 {Stockfish says this move is fine but I'm not sure why. The rook has at least two other escape squares, and this allows a discovered attack.} (1... Ra7 2. Nc6 Rd7 3. Ne5 Ra7 {White doesn't want to repeat moves because they are winning, so now White's attack is temporarily stymied. Stockfish suggests Qf2 and further developing moves.}) (1... Rb7 2. Qf3 Rc7 {This is the Stockfish line following Rb7. It seems that Stockfish doesn't like the rook on b7, probably because d6 is strong if the rook stays put.}) 2. Nxg6 {Fork number 1.} e5 {Refuted!} 3. Nxe5 (3. dxe6 {The wildest line I saw in my entire analysis. I failed to consider this at the time because I forgot that the rook on c7 is still attacked by the bishop, but frankly I find it hard to believe that I could have found all of these moves.} Rxc4 {The rook is hanging, so it had to move somewhere, but I think we sacrifice it to prevent lines involving exf7+.} 4.e7 {And then White just goes after the other rook instead.} Rc6 5.exf8=Q+ Bxf8 6.Ne5 {And the knight escapes!}) Qe7 {Again, Stockfish thinks that Qe7 is an OK-but-not-best move, but I don't see why the queen even should move at all, let alone to e7.} (3... Rc8 4. Qh5 {Stockfish line. From here, Stockfish makes a lot of mating threats and generally plays like it's an endgame, despite the fact that both queens and all four rooks are still on the board.}) 4. Ng6 {Fork number 2.} hxg6 {Not a direct refutation, but we don't want to sacrifice two minor pieces for one rook.} 5. d6 {Fork number 3, and this one finally sticks.}

```

I missed Bb5, and in retrospect it is clearly the best move in this position, both by my own analysis and according to Stockfish 14. But Stockfish also seems to think that I didn't make any serious mistakes in playing this line, which doesn't tally with my own analysis (as I have annotated above). Bb5 immediately wins 2 points of material (rook for bishop), but I had to find three separate forks in order to justify Ne5, and the first fork was almost fully refuted (I won a pawn). It seems like Black should have been able to avoid losing an exchange here with better play, but Stockfish says that Ne5 is only slightly less advantageous for White than Bb5.

Am I missing something, or is this just a case of "when one side is completely winning, the evaluation gets a bit imprecise" and in fact Ne5 was a poor move?

# Answer
The non-technical answer is that once you have such a winning position, the "winning difference" between the best (e.g. winning material) vs a good improving move evaluated by the engine is based on the fact that your position is already extremely winning. You could literally play any decent move and it would not be a mistake. An extreme example could be that you have 10 queens and accidentally blunder one - that wouldn't matter at all, you still have stock left over.

A number of factors in the given position gives Stockfish this designation. One being Black's terrible positioning of its pieces and another being being up 2 minor pieces.
> 4 votes

# Answer
Ne5 was not a poor move, but indeed not the best. When Ne5 is played, white has an extreme attack with knight, bishop and if needed, queen and can still easily win an exchange after 1. ... Rd6 2. Nc6 Rf6 3. Be5 (close to stockfish play) and easily win the game because blacks defence is not enough, even to Stockfish standards
> 2 votes

---
Tags: analysis, tactics, middlegame, evaluation
---


# Question
Title: Clarifications on the number of nodes explored per seconds
I am trying to understand exactly what is meant when a chess engine is reporting a number of explored nodes per second. For example, on a single thread, Stockfish is reporting about 1.5 million nodes explored per second (1.5 kN/s). My main question is whether:

1. the positions explored during the typical quiescence phase are also taken into account
2. positions already stored/analyzed in the transposition table are also taken into account

# Answer
Nodes are just positions encountered or seen or visited during a search. Positions can be generated when an engine makes a move internally.

Example:
Starting from start position the engine may explore e4 e5, that is 3 nodes.
startpos = 1 (fen: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1)
pos after e4 = 1 (fen: rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1)
pos after e5 = 1 (fen: rnbqkbnr/pppp1ppp/8/4p3/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 2)
total = 3 nodes or positions.

1. Positions in qsearch() has to be counted as well as they are positions.
2. Positions in the transposition table would not be counted as they are already counted assuming that it was counted when it was visited.
> 2 votes

---
Tags: engines, programming
---


# Question
Title: What is the most queens that have been on the board in a grandmaster game?
There are quite a few grandmaster games with 3 queens or 4 queens, but what is the highest number of queens on the board in a game between two GMs?

I'd be interested in both the most on the board at the same time and the most total during the game.

# Answer
This sounds like a job for Tim Krabbé, who presents two games with six queens: Szalanczy - Nguyen, Budapest 2009 and Anton - Franco, XXI Elgoibar Magistral 2011. I don't know how many of the participants were grandmasters.

There are some other games with 5+ queens at Chess Siberia. Of these, Miton - Benjamin, World Open Philadelphia 2005 definitely features two grandmasters.
> 13 votes

# Answer
If you have a PGN file of chess games you can use CQL to search it. Something like:

```
(match
  :pgn src.pgn
  :output queens.pgn
  (position
    :piececount [Qq] 3 8))

```

Should return all games with positions containing 3 to 8 Queens on the board.

**Edit:** The Aquarium interface from chessok has a CQL search capability and can read ChessBase databases, so I was able to search my reference database (5M+ games) to games with 5 or more queens. There were no GM games with more than 5 queens on the board. The Anton Guijarro - Franco game mentioned by dfan, is a GM (Anton) vs an IM (Franco). In addition to the Miton - Benjamin game mentioned by dfan, I found a game played about a month later, Hickl - Sokolov that had 5 queens.

Miton - Benjamin:

```
[Event "World op 33rd Philadelphia  6/??/2005"]
[Site "?"]
[Date "2005.07.03"]
[Round "7"]
[White "Miton Kamil"]
[Black "Benjamin Joel"]
[Result "1-0"]
[Annotator ""]
[BlackElo "2563"]
[ECO "E33"]
[GameNo "3367517"]
[Source "ChessBase 11/10/1998"]
[WhiteElo "2592"]
[FEN ""]

1. d4 Nf6 2. Nf3 Nc6 3. c4 e6 4. Nc3 Bb4 5. Qd3 d6 6. a3 Bxc3+ 7. Qxc3 O-O 8.
e3 a5 9. Be2 Re8 10. b3 e5 11. d5 Ne7 12. Nd2 Bf5 13. O-O c6 14. dxc6 Nxc6 15.
Rd1 Rc8 16. Qb2 Qe7 17. Nb1 b5 18. Nc3 bxc4 19. bxc4 Ne4 20. Nb5 Red8 21. f3
Nc5 22. e4 Be6 23. Be3 Rb8 24. Qc3 a4 25. Rac1 Nb3 26. Rc2 h6 27. f4 f6 28.
Qe1 Bf7 29. Qf2 exf4 30. Qxf4 Ne5 31. Nc3 Nc5 32. Nd5 Bxd5 33. cxd5 Rb3 34.
Bxc5 dxc5 35. Bc4 Nxc4 36. Rxc4 Rxa3 37. d6 Qe6 38. Rxc5 Rb3 39. Ra5 a3 40.
Ra7 Rd7 41. Rxd7 Qxd7 42. e5 Rb2 43. Qc4+ Kh7 44. e6 Qa7+ 45. Qd4 Qb7 46. Qd3+
g6 47. Qf1 a2 48. e7 Rb1 49. e8=Q a1=Q 50. d7 Qb6+ 51. Kh1 Rxd1 52. Qe7+ Kg8
53. d8=Q+ Qxd8 54. Qxd8+ Rxd8 55. Qxa1 Rc8 56. h4 Rd8 57. Qa2+ Kg7 58. Kg1 Rd7
59. Kf2 Re7 60. Kf3 Rf7 61. Qa8 Re7 62. Qd8 Re5 63. Qd7+ Kf8 64. Qh7 Re6 65.
Qh8+ Kf7 66. Qc8 Ke7 67. Qh8 g5 68. Qh7+ Kd6 69. Qg7 Ke5 70. Qxh6 Rd6 71. Qh7
Re6 72. Qh5 1-0

```

Hickl - Sokolov:

```
[Event "Mainz Ordix op Mainz  8/13/2005"]
[Site "?"]
[Date "2005.08.14"]
[Round "7"]
[White "Hickl Joerg"]
[Black "Sokolov Ivan"]
[Result "1-0"]
[Annotator ""]
[BlackElo "2691"]
[ECO "A07"]
[GameNo "3404712"]
[Source "ChessBase 11/10/1998"]
[WhiteElo "2537"]
[FEN ""]

1. g3 d5 2. Nf3 c6 3. Bg2 Bg4 4. b3 Nd7 5. Bb2 Bxf3 6. Bxf3 e5 7. d3 Ngf6 8.
O-O h5 9. c4 d4 10. Re1 Bc5 11. Na3 Bb4 12. Rf1 Nf8 13. Nc2 Be7 14. e3 Ne6 15.
exd4 exd4 16. Re1 Qd7 17. Qd2 h4 18. Rad1 Rd8 19. b4 Kf8 20. Re2 c5 21. bxc5
Bxc5 22. Nb4 hxg3 23. hxg3 Nc7 24. Rde1 a5 25. Nc2 b6 26. Ba3 Ne6 27. Re5 g6
28. Rxe6 fxe6 29. Bxc5+ bxc5 30. Qxa5 Rc8 31. Na3 Kg7 32. Re5 Qe7 33. Nb5 Nd7
34. Re2 Qg5 35. Qe1 e5 36. Nd6 Rb8 37. Bg2 Rb6 38. Nb5 Ra6 39. Rb2 Rb8 40. Bh3
Nf6 41. Re2 e4 42. dxe4 Nh5 43. Bg2 Rab6 44. e5 d3 45. Rd2 Rxb5 46. cxb5 c4
47. e6 Rd8 48. Rd1 d2 49. Qe4 c3 50. b6 Qf5 51. e7 c2 52. Rf1 d1=Q 53. exd8=Q
Qxd8 54. Qb4 Qd1 55. b7 c1=Q 56. b8=Q Qxf1+ 57. Bxf1 Nf6 58. Q4f8+ 1-0

```

Anton Guijarro - Franco:

```
[Event "XXI Elgoibar Magistral Elgoibar ESP 12/14/2011"]
[Site "?"]
[Date "2011.12.18"]
[Round "6.4"]
[White "Anton Guijarro D"]
[Black "Franco Alonso A"]
[Result "1-0"]
[Annotator ""]
[BlackElo "2454"]
[ECO "A17"]
[GameNo "4719077"]
[Source "ChessBase 11/10/1998"]
[WhiteElo "2469"]
[FEN ""]

1. Nf3 Nf6 2. c4 e6 3. Nc3 b6 4. g3 Bb7 5. Bg2 Be7 6. O-O O-O 7. Re1 Ne4 8.
Nxe4 Bxe4 9. d3 Bb7 10. e4 c5 11. d4 cxd4 12. Nxd4 Nc6 13. Bf4 Nxd4 14. Qxd4
Bc5 15. Qd2 Qe7 16. a3 e5 17. Be3 a5 18. Rad1 Bc6 19. Bh3 Ra7 20. Bg5 f6 21.
Be3 a4 22. Bf1 Qe6 23. Qd3 Rc8 24. h4 Rac7 25. Kh2 Qe7 26. Rd2 Bxe3 27. Qxe3
Qc5 28. Qf3 Rf8 29. Qg4 Rcc8 30. h5 Rce8 31. Re3 Re6 32. Qd1 Re7 33. Bh3 Rff7
34. Bf5 Qxc4 35. Rc3 Qb5 36. Kg2 Rf8 37. Qg4 Kh8 38. Rcd3 Qc4 39. Rd6 Bb5 40.
Bxd7 Qf1+ 41. Kh2 Bxd7 42. Rxd7 Rxd7 43. Qxd7 h6 44. Qe7 Rg8 45. Qd6 Qe1 46.
Qb4 b5 47. Kg2 Kh7 48. Rd5 Qe2 49. Rd7 Rc8 50. Rxg7+ Kxg7 51. Qe7+ Kg8 52.
Qe6+ Kg7 53. Qd7+ Kf8 54. Qxc8+ Ke7 55. Qf5 Qxb2 56. Qh7+ Ke6 57. Qxh6 b4 58.
Qg6 bxa3 59. h6 a2 60. h7 a1=Q 61. Qf5+ Kd6 62. h8=Q Kc5 63. Qf8+ Kc4 64. Qe6+
Kd3 65. Qfxf6 Qd4 66. Qf3+ Kd2 67. Qh6+ Kc2 68. Qc6+ Kb1 69. g4 Qab2 70. g5 a3
71. g6 a2 72. g7 a1=Q 73. g8=Q Qaa3 74. Qgg3 Qxf3+ 75. Qxf3 Qc2 76. Qb5+ Qcb2
77. Qfd3+ Qxd3 78. Qxd3+ Kc1 79. Kf3 Qd4 80. Qe2 Qd6 81. Qc4+ Kd2 82. Qd5+ 1-0

```
> 11 votes

# Answer
Using the more recent version of CQL, this is even simpler:

```
// Chess Q 12704
// find positions with many queens

cql(input Mega_Database_2022.pgn)

sort #[Qq] >= 5

```

Finds all games that have 5 or more queens on the board and sorts them by the amount found. A total of 49 games were returned when I ran the script against Mega Database 2022. 22 (!) of these were online, played in 2020-2021. Some were pretty ridiculous (with 7 queens on the board!). Here are some interesting ones between IMs/GMs:

1. Postny Evgeny vs. Gordievsky, Dmitry at the 12th PNWCC Online blitz JP (2020):

```
[FEN ""]
[Event "PNWCC Online blitz JP 12th"]
[Site "Lichess.org INT"]
[Date "2020.06.06"]
[Round "11"]
[White "Postny, Evgeny"]
[Black "Gordievsky, Dmitry"]
[Result "1-0"]
[ECO "C67"]
[WhiteElo "2600"]
[BlackElo "2559"]
[StartPly "90"]

1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O Nxe4 5. d4 Nd6 6. Bxc6 dxc6
7. dxe5 Nf5 8. Qxd8+ Kxd8 9. Nc3 Be7 10. h3 Nh4 11. Nd4 Nf5
12. Nde2 h5 13. Ne4 h4 14. Bg5 Bxg5 15. Nxg5 Ke7 16. Nf4 Rh6
17. Rad1 a5 18. Rd2 Bd7 19. Nxf7 Rh7 20. Ng5 Rh6 21. Rfd1 Be8
22. a4 Rc8 23. b3 c5 24. Rd3 c4 25. Nd5+ Kf8 26. Rf3 g6 27. Nxc7 Bc6
28. Rf4 Ke7 29. Nd5+ Bxd5 30. Rxd5 c3 31. Rxa5 Rhh8 32. Rb5 Rc7
33. Nf3 Rd8 34. Nxh4 Rd2 35. Nxg6+ Ke6 36. Nf8+ Ke7 37. Rxf5 Rxc2
38. Ng6+ Ke8 39. Rf8+ Kd7 40. Rf7+ Kc8 41. Rxc7+ Kxc7 42. Rc5+ Kb6
43. Rc4 Rc1+ 44. Kh2 c2 45. e6 Ka5 46. e7 b6 47. e8=Q Rh1+ 48. Kxh1 c1=Q+
49. Rxc1 Kb4 50. Qb5+ Ka3 51. Qxb6 Kb2 52. Rc4 Ka1 53. Rc2 Kb1 54. Re2 Ka1
55. Nf4 Kb1 56. h4 Ka1 57. h5 Kb1 58. h6 Kc1 59. h7 Kb1 60. h8=Q Kc1
61. g3 Kb1 62. g4 Kc1 63. Qh2 Kb1 64. g5 Kc1 65. g6 Kb1 66. g7 Kc1
67. g8=Q Kb1 68. a5 Kc1 69. a6 Kb1 70. a7 Kc1 71. a8=Q Kb1 72. Qbb8 Kc1
73. b4 Kd1 74. b5 Kc1 75. b6 Kd1 76. Qbf8 Kc1 77. b7 Kd1 78. b8=Q Kc1
79. Qfe8 Kd1 80. Ng2 Kc1 81. f4 Kd1 82. f5 Kc1 83. f6 Kd1 84. f7 Kc1
85. f8=Q Kd1 86. Qhh8 Kc1 87. Kh2 Kd1 88. Kh3 Kc1 89. Kh4 Kd1 90. Kg5 Kc1
91. Kf6 Kd1 92. Ke7 Kc1 93. Kd8 Kd1 94. Nf4 Kc1 95. Ng6 Kd1 96. Qh5 Kc1
97. Ne7 Kd1 98. Nc8 Kc1 99. Qhh8 Kd1 100. Rh2 Kc1 101. Qh1# 1-0

```
2. Synchev, Klemetry vs. Shahade, Gregory P at a Titled Tuesday blitz on chess.com (2020):

```
[FEN ""]
[Event "Titled Tuesday intern op 16th June"]
[Site "Chess.com INT"]
[Date "2020.06.16"]
[Round "8"]
[White "Sychev, Klementy"]
[Black "Shahade, Gregory P"]
[Result "1-0"]
[ECO "D82"]
[WhiteElo "2572"]
[BlackElo "2476"]
[StartPly "114"]

1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. Bf4 Bg7 5. Qa4+ Bd7 6. Qb3 dxc4 7. Qxb7 Bc6 8.
Qxc7 Qxc7 9. Bxc7 O-O 10. Nf3 Nbd7 11. e3 Rfc8 12. Bg3 Nh5 13. Be2 Nxg3 14.
hxg3 Rab8 15. O-O-O e6 16. Ne1 Nb6 17. Bf3 Bxf3 18. Nxf3 Bf8 19. Kc2 Nd5 20.
Nxd5 exd5 21. Rb1 Rb7 22. Rhc1 a5 23. Ng1 a4 24. Ne2 Bb4 25. Kd1 Rcb8 26. Rc2
Kf8 27. Nf4 Rb5 28. Ne2 Ke7 29. g4 Kd6 30. g5 Ba5 31. a3 Bd8 32. f4 Be7 33. Nc3
Ra5 34. Rf2 Kc6 35. Kc2 Ra7 36. g4 Ra5 37. Rh2 Ra7 38. Rxh7 Rab7 39. Rxf7 Kd6
40. Rg7 Ke6 41. Rxg6+ Kf7 42. Ra6 Rh8 43. Nxd5 Rh2+ 44. Kc3 Rb3+ 45. Kxc4 Rc2+
46. Nc3 Rcxc3+ 47. bxc3 Rxb1 48. Rxa4 Re1 49. Kd3 Rd1+ 50. Ke4 Rg1 51. Kf5 Rc1
52. Rc4 Rb1 53. g6+ Kf8 54. e4 Rb6 55. e5 Kg7 56. Rc7 Kf8 57. g7+ Kf7 58. Rxe7+
Kg8 59. Re8+ Kxg7 60. Re7+ Kg8 61. Rd7 Kf8 62. d5 Ke8 63. Ra7 Kf8 64. d6 Ke8
65. Ke6 Kf8 66. f5 Rb7 67. Ra8+ Kg7 68. Rd8 Kh6 69. f6 Rh7 70. f7 Kg5 71. Rg8+
Kf4 72. f8=Q+ Ke4 73. Qf5+ Ke3 74. Qxh7 Kd2 75. c4 Kc3 76. c5 Kd4 77. c6 Kc5
78. c7 Kb6 79. c8=Q Kb5 80. g5 Ka4 81. Qhc7 Kb3 82. Q7b7+ Ka2 83. d7 Ka1 84.
d8=Q Ka2 85. Rh8 Ka1 86. g6 Ka2 87. g7 Ka1 88. Kf6 Ka2 89. e6 Ka1 90. e7 Ka2
91. e8=Q Ka1 92. Rh1+ Ka2 93. g8=Q+ Kxa3 94. Qbb3# 1-0

```
3. Alavi Moghaddam, Sayed Javad vs. Omariev, Maksim at a Titled Tuesday blitz on chess.com (2021):

```
[FEN ""]
[Event "Titled Tuesday intern op 06th July"]
[Site "Chess.com INT"]
[Date "2021.07.06"]
[Round "2"]
[White "Alavi Moghaddam, Sayed Javad"]
[Black "Omariev, Maksim"]
[Result "1-0"]
[ECO "B22"]
[WhiteElo "2445"]
[BlackElo "2304"]
[StartPly "78"]

1. e4 c5 2. c3 Nf6 3. e5 Nd5 4. d4 cxd4 5. cxd4 e6 6. Nf3 b6 7. Bc4 Bb7 8. O-O
Be7 9. Bxd5 Bxd5 10. Nc3 Bxf3 11. Qxf3 Nc6 12. Qg3 Nxd4 13. Qxg7 Rf8 14. Qxh7
Nf5 15. Nd5 d6 16. Nxe7 Qxe7 17. exd6 Qf6 18. Qh5 Rh8 19. Qf3 Rd8 20. Rd1 Kf8
21. Bf4 Nh4 22. Qe3 Nf5 23. Qe5 Qxe5 24. Bxe5 Rh6 25. Rac1 f6 26. Bf4 e5 27.
Bxh6+ Nxh6 28. d7 Ke7 29. Rc8 Nf7 30. Rxd8 Kxd8 31. h4 Ke7 32. h5 Kd8 33. g4 e4
34. Kg2 Ne5 35. h6 Nf7 36. h7 b5 37. b4 a6 38. a3 f5 39. gxf5 e3 40. fxe3 Nh8
41. e4 Nf7 42. e5 Nh8 43. e6 Nf7 44. exf7 a5 45. bxa5 Kc7 46. d8=Q+ Kc6 47.
f8=Q b4 48. axb4 Kb5 49. h8=Q Ka6 50. Qfe7 Kb5 51. f6 Ka4 52. f7 Kb3 53. f8=Q
Ka2 54. b5 Kb3 55. b6 Ka4 56. a6 Kb5 57. a7 Kc6 58. a8=Q+ Kb5 59. b7 Kc4 60.
Qhg7 Kb3 61. b8=Q+ Kc2 62. Qbc8+ Kb3 63. Qab8+ Ka2 64. Qff7# 1-0

```

Some more serious (and fascinating) ones:

1. Li, Di vs. Xu, Xiangyu at the Chinese National Rapid Championship (2017):

```
[FEN ""]
[Event "CHN-ch rapid"]
[Site "Shenzhen"]
[Date "2017.12.07"]
[Round "4"]
[White "Li, Di"]
[Black "Xu, Xiangyu"]
[Result "1/2-1/2"]
[ECO "D44"]
[WhiteElo "2485"]
[BlackElo "2549"]
[StartPly "58"]

1. d4 d5 2. Nf3 Nf6 3. c4 e6 4. Nc3 c6 5. Bg5 dxc4 6. e4 b5 7. e5 h6 8. Bh4 g5
9. Nxg5 hxg5 10. Bxg5 Nbd7 11. g3 Bb7 12. Bg2 Qb6 13. exf6 c5 14. d5 O-O-O 15.
O-O b4 16. Na4 Qb5 17. a3 exd5 18. axb4 cxb4 19. Be3 Nc5 20. Qg4+ Rd7 21. Nxc5
Bxc5 22. Bxc5 Qxc5 23. Rfe1 Kc7 24. Re5 Rhd8 25. h4 Bc6 26. h5 a5 27. h6 a4 28.
h7 a3 29. bxa3 b3 30. Rae1 b2 31. Qe2 c3 32. Re8 Rxe8 33. Qxe8 c2 34. Qe5+ Rd6
35. Qe7+ Bd7 36. h8=Q b1=Q 37. Bf1 Kb7 38. Qh6 Qd1 39. Qhf8 Qdd4 40. Re3 c1=Q
41. Rb3+ Qb6 42. Rxb6+ Qxb6 43. Qxd6 Qxf1+ 44. Kxf1 Qb1+ 45. Kg2 Qe4+ 46. Kh2
Qh7+ 1/2-1/2

```
2. Arnaudov, Petar G vs. Moser, Eva at the 4th Augsburg Gutmann Memorial (2013):

```
[FEN ""]
[Event "Augsburg Gutmann Memorial 4th"]
[Site "Augsburg"]
[Date "2013.12.31"]
[Round "5"]
[White "Arnaudov, Petar G"]
[Black "Moser, Eva"]
[Result "0-1"]
[ECO "A80"]
[WhiteElo "2442"]
[BlackElo "2436"]
[StartPly "54"]

1. d4 f5 2. Bg5 h6 3. Bh4 g5 4. e3 Nf6 5. Bg3 d6 6. h4 g4 7. Bd3 Nc6 8. Ne2 e5
9. Bb5 Qe7 10. c4 Bd7 11. Nbc3 Bg7 12. d5 Nd8 13. Bxd7+ Qxd7 14. Qc2 O-O 15. e4
f4 16. Bh2 Nh5 17. O-O-O Nf7 18. f3 g3 19. Bg1 Qe7 20. Kb1 Bf6 21. Nc1 Nh8 22.
b4 Ng6 23. c5 Nxh4 24. Nb3 b6 25. Rc1 Ng7 26. Nb5 h5 27. a4 Qd7 28. Qe2 Rfc8
29. a5 bxc5 30. bxc5 a6 31. c6 Qe7 32. Na7 Rcb8 33. Ka2 Rb4 34. Rxh4 Bxh4 35.
Rc4 Rbb8 36. Ra4 Bf6 37. Qxa6 h4 38. Qb7 Qf7 39. a6 h3 40. gxh3 Qh5 41. Nb5 Ne8
42. Nxc7 Nxc7 43. Qxc7 Qxf3 44. Bb6 Qg2+ 45. Ka3 Qxh3 46. a7 Re8 47. Qb7 f3 48.
Bc7 f2 49. Bb8 f1=Q 50. Qxa8 g2 51. Qb7 g1=Q 52. a8=Q Qc5+ 53. Qb4 Qa1# 0-1

```
3. Belov, Igor vs. Prohorov, Vladimir (1991 - the oldest I found):

```
[FEN ""]
[Event "Cheliabinsk op"]
[Site "Cheliabinsk"]
[Date "1991"]
[Round "?"]
[White "Belov, Igor"]
[Black "Prohorov, Vladimir"]
[Result "0-1"]
[ECO "E97"]
[WhiteElo "2440"]
[BlackElo "2230"]
[PlyCount "164"]
[StartPly "56"]

1. Nf3 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. d4 O-O 6. Be2 e5 7. O-O Nc6 8. d5
Ne7 9. Bg5 h6 10. Bxf6 Bxf6 11. b4 Bg7 12. c5 f5 13. Nd2 Kh7 14. Rc1 Ng8 15.
cxd6 cxd6 16. Nb5 Nf6 17. Nc7 Rb8 18. Bd3 f4 19. Qa4 a6 20. b5 Nh5 21. f3 Rf7
22. b6 Bf8 23. Qb3 Ng7 24. Rc2 Qf6 25. Rfc1 Bd7 26. Bxa6 bxa6 27. Nxa6 Rb7 28.
Rc7 Qg5 29. h4 Rxc7 30. Nxc7 Qxh4 31. b7 Nh5 32. b8=Q Ng3 33. Qc4 Qh1+ 34. Kf2
Qh4 35. Kg1 Qh1+ 36. Kf2 Qh4 37. Kg1 Qh1+ 38. Kf2 Qh4 39. Qb6 Be7 40. Nf1 Qh1
41. Nd2 Qh4 42. Ke1 Qh1+ 43. Nf1 Bh4 44. Kd2 Qxg2+ 45. Kc3 Ne2+ 46. Kb2 Nxc1+
47. Kxc1 Qxf3 48. Ne6 Qa3+ 49. Kd2 Be7 50. Qcb3 Qa8 51. Qc7 Be8 52. a3 Qa6 53.
Qcc4 Qa7 54. Qf3 Bh4 55. Qh3 g5 56. Nd8 Bd7 57. Qhc3 Rg7 58. Nc6 Qg1 59. Kc2 g4
60. Nb8 Be8 61. Nd2 Bg6 62. Qc8 Qg2 63. Nd7 Be7 64. Nxe5 dxe5 65. Qxe5 Bxa3 66.
Qcc3 Bf8 67. d6 f3 68. d7 f2 69. d8=Q f1=Q 70. Qde7 Qf7 71. Qxf7 Bxf7 72. Qf5+
Kg8 73. Qfc8 Qf2 74. Qb4 Bg6 75. Qbc4+ Kh7 76. Qxg4 Bd6 77. Qce6 Bb4 78. Qd5
Rc7+ 79. Kd1 Bxd2 80. Qxd2 Qf1+ 81. Qe1 Rc1+ 82. Kxc1 Qxe1+ 0-1

```
4. Mackic, Zoran vs. Maksimenko, Andrei (1994 - pretty old as well):

```
[FEN ""]
[Event "YUG-chT2"]
[Site "Yugoslavia"]
[Date "1994"]
[Round "5"]
[White "Mackic, Zoran"]
[Black "Maksimenko, Andrei"]
[Result "0-1"]
[ECO "B96"]
[WhiteElo "2400"]
[BlackElo "2430"]
[StartPly "68"]

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Bg5 e6 7. f4 Nc6 8. Nxc6
bxc6 9. e5 h6 10. Bh4 g5 11. fxg5 Nd5 12. Nxd5 cxd5 13. Qh5 Qb6 14. Be2 Bg7 15.
g6 O-O 16. Bf6 Ra7 17. Bxg7 Kxg7 18. gxf7 Raxf7 19. Qg4+ Kh8 20. O-O-O Qe3+ 21.
Kb1 dxe5 22. Rhe1 Rg7 23. Qb4 Qf4 24. Qd6 e4 25. Qa3 Rxg2 26. Bxa6 Bxa6 27.
Qxa6 Qe5 28. Rf1 Rb8 29. Qa3 e3 30. Rf8+ Rxf8 31. Qxf8+ Kh7 32. Qf7+ Rg7 33.
Qf3 d4 34. a4 Qf5 35. Qe2 e5 36. a5 Qf2 37. Qd3+ Kh8 38. Qe4 Qxh2 39. a6 Qf4
40. Qh1 Kh7 41. Rf1 Qg4 42. Qd5 e4 43. Qa5 d3 44. a7 d2 45. a8=Q e2 46. Rf6
d1=Q+ 47. Ka2 e1=Q 48. Rxh6+ Kxh6 49. Qh8+ Kg6 50. Qa6+ Kf7 51. Qb7+ Qdd7 0-1

```

Reference (from the CQL documentation):

Download CQL for Windows and Mac along with some examples from the official website. Email the authors for the Linux distribution.
> 0 votes

---
Tags: grandmaster, records, pawn-promotion, queens, famous-games
---


# Question
Title: When material is counterproductive (construction task)
Give a position where :

> White has all 16 pieces. Black has a king and a single pawn, White, to move, loses. Bonus kudos if White can't stop a #1. Remove any single piece (except the kings, of course), and White wins

Since there surely are many solutions, give your shortest proof game and the shortest of all entries may win. If they are equal, the first poster wins.

EDIT: A small clarification. Yes, you may use promoted material and even an illegal pawn structure, but you hardly will gain anything as these are move-eaters.

# Answer
Many solutions indeed exist. The hard part is actually finding one. All pieces must be intertwined. With a few promoted bishops, I have managed to find one. It can be reached in **55 moves.**

```
[FEN ""]
[startply "110"]

1. h4 g5 2. hxg5 h6 3. Rxh6 Rh7 4. f4 Rg7 5. f5 Rg6 6. fxg6 e6 7. gxf7+ Ke7 8. Nf3 Kd6 9. Nh4 Ke5 10. fxg8=B Kf4 11. a4 b5 12. axb5 Kg3 13. d4 Kh2 14. Bf4+ Kh1 15. Bh2 e5 16. dxe5 Qe7 17. g6 Qh7 18. gxh7 d5 19. c4 a5 20. cxd5 c6 21. dxc6 a4 22. c7 Ra6 23. Qd5 Bf5 24. Qa8 Rd6 25. Kf2 Be7 26. Kf3 Bf6 27. Kf4 Nc6 28. b4 Na5 29. bxa5 Rd1 30. Nc3 Re1 31. e4 Rd1 32. Bd3 Rg1 33. Kxf5 Re1 34. Kxf6 Rf1+ 35. Kg7 Re1 36. g3 Rg1 37. Rf1 a3 38. Rf8 Rf1 39. e6 Rg1 40. Kh8 Re1 41. e7 Rf1 42. a6 Re1 43. a7 Rd1 44. b6 Rg1 45. b7 Rf1 46. c8=B Re1 47. e8=B Rc1 48. e5 Rd1 49. Bdg6 Re1 50. Bcf5 Rd1 51. Bef7 Rf1 52. Nd1 Rf2 53. e6 Re2 54. Ne3 Rg2 55. Nexg2 a2

```
> 2 votes

---
Tags: problems, material-balance
---


# Question
Title: Formal rules for two-player bughouse without a clock
I would like to know what are the formal rules for two-player bughouse without a clock. I'd like to think of each team as a single player.

It seems to me that bughouse chess works primarily because of the time limit imposed by the clock. If one should remove the clock, then it is easy to imagine a position where both teams are at a disadvantage to move first. Perhaps it is one team's turn to move on board 1 and the other team's turn on board 2, but whoever moves first will be put at a disadvantage on the other board because of a resulting capture. In such a case, neither player wants to go first, and the game enters a deadlock, with no team specifically to blame for not having moved.

Are there formal rule sets for bughouse chess that eliminate the possibility of such a deadlock?

I suppose that if one insists that play proceeds on each board in turn (white on board 1, black on board 2, white on board 2, black on board 1, repeat), then it would resolve this issue, since it would at any stage be a certain player's obligation to move, just as in any game. But in practice, bughouse chess does not obey such a convention, and I wonder whether there is a way to set up the rules to more closely follow the practice, but while avoiding the problematic kind of deadlock where neither team wants to move, but nobody is obliged to move.

# Answer
In bughouse, there are no formal rules, since it isn't exactly a formal game.

But from my experience, the two most common ways to deal with this are:

* A player counts to 10 after moving, and his opponent has to move before he reaches 10.
* You are only obligated to move once the person sitting diagonally from you (your opponent's partner) moves.

Other than these, I don't know of any other effective rules that would work. I've played with some very strong bughouse players (borderline professionals), and even they often just resort to counting.
> 4 votes

# Answer
The way I've played it is an alternative. The rule is that you can't stall for more than three moves of your teammate (so if your teammate has made his third move since your last you must move before he can move again).

Of course this still isn't a good role for serious competition because you do need a kind of gentlemans agreement so that you don't have one player on each side stalling. But for playing with friends I think it's an OK compromise (even though just like in zh, time pressure for me is part of the fun in bughouse).
> 4 votes

# Answer
Here is a rule that I think works:

> **Every piece you capture can be dropped by your partner only after his/her next move.**

This prevents the situation you mentioned. Of course, it is still possible to reach a situation where each team has the turn at one board but does not want to move, but the specific problem you ask about would be mostly eliminated.
> 1 votes

# Answer
Here is a set of rules that works fully:

1. At any time exactly one board is **obligated** (initially the board for Team 1 White).
2. If both players in the same team have the turn, then one of them must move.
3. If one player in each team has the turn, then the player at the obligated board must move.
4. Each player who moves at an obligated board may change which board is obligated.

For actual play, we can use a chit to denote the obligated board, and each player who moves at an obligated board chooses whether to leave the chit at that board or shift the chit to the other board.

This rule-set guarantees progress, and yet allows a high degree of freedom in play since each player can always make a move whenever he/she has the turn. Also, neither team can copy the other team to force a draw — Team 1 cannot copy due to (1); Team 2 cannot copy since T1W (Team 1 White) can choose not to change the obligated board, forcing T2B to respond to that first move before T1B needs to make any move.

Note that your proposal (T1W, T1B, T2W, T2B, \[repeat\] ...) is actually bad because it allows Team 2 to copy Team 1 to force a draw. Incidentally, (T1W, T2W, T2B, T1B, \[repeat\] ...), which avoids this problem, is permitted by my rule-set but may not include the optimal strategy.

Also, as I said in a comment on another answer, the diagonal-obligation-rule fails when both you and the diagonally-opposite player have the turn but do not want to move (e.g. if it allows your opponent to capture your queen and pass to the partner).

~ ~ ~

Now here is the mathematics behind this rule-set.

First of all, due to the concurrency, it is not at all obvious that this rule-set even yields a well-defined abstract game with perfect play! We formally define this game as follows. A **strategy** for a team is a function S on all possible game states such that for each possible game state X we have that S(X) is ∅ or the set with the desired move (at a board where a player of the team has the turn). The **play** given the strategies S1,S2 for the two teams is the result of starting from the initial state and then from each state X always following one of the moves in S1(X)⋃S2(X). The **guaranteed value** of a given strategy for a given team is the minimum possible value of the play outcome (win = 1 and draw = 0 and loss = −1) for that team over all possible plays in which that team uses that strategy. The **guaranteeable value** for a given team is the maximum possible guaranteed value of a strategy for that team.

So even after fixing the teams' strategies, the play is non-deterministic, due to the non-deterministic choices whenever both teams have a desired move but only one is followed. Thus such a game may not be zero-sum (in general), meaning that it may be that the sum of guaranteeable values for the two teams may not be 0. (It may be −1 or −2.) However, I claim that the bughouse chess variant I gave above is in fact zero-sum!

To justify that, for each team T we can consider the variant where T has the priority whenever both teams have a desired move but T is not obliged to move. We denote a strategy for this variant by saying it is a strategy for T\*. Note that a strategy for T\* can do whatever a strategy for T can, against the same class of opponent strategies.

I claim that any strategy for T1\* (with priority) cannot do better than some strategy for T1 (without priority) that always waits when not obliged to move. To simplify the analysis, we assume without loss of generality that no game state is reachable via two distinct sequences of moves.

Consider any strategy S1 for T1\* against T2\*. We shall iteratively modify S1 to remove reliance on priority without worsening the outcome for T1. At the k-th step, consider any possible game state X reachable by exactly k moves such that S1 relies on priority at X (i.e. T1 is not obliged to move but forces the next move to be S1(X) instead of T2's desired move), and consider any possible desired move m for T2 from X. Let X+m denote the game state after making move m from X. Let S1' be the same as S1 except that S1'(X) = ∅ and S1'(X+m) for each such m is defined by:

* If m does not change the obligated board: S1'(X+m) is S1(X).
* If m changes the obligated board: S1'(X+m) is S1(X) plus no change in obligated board.

This definition is valid since each such X+m can be reached only by one sequence of moves and that sequence has length (k+1). Now observe that after X+m only T1 can move, and X+m+S1'(X+m) is exactly the same as X+S1(X)+m. Thus S1 cannot do better than S1' since after X+S1(X) only T2 can move and so T2 can force the next move to be m.

At the end of this process, we have a strategy for T1\* against T2\* that always waits when not obliged to move but still does at least as well as S1.

Therefore there is some optimal strategy S1\* for T1\* against T2\* that always waits when not obliged to move. Likewise there is some optimal strategy S2\* for T2\* against T1\* that always waits when not obliged to move. Observe that both since S1\* and S2\* are strategies for T1\* and T2\* respectively, they can decide all the non-deterministic choices, and hence T1\* against T2\* is a zero-sum game. But S1\* works at least as well for T1 against T2, and likewise S2\* for T2 against T1, so they are optimal strategies for the original variant.

This argument fails if we modify "may" to "must" in rule (4)! It may be a fun exercise to come up with a counter-example. I think that requiring the obligated board to change whenever a move is made at it can be achieved only via synchronization (e.g. the obligated player's desired move is executed first before the non-obligated player's desired move if any), which is very difficult to implement in human play — what if T1W has the chit and makes a move at the same time as T2W, and T2W does not want to get the chit otherwise it would be passed to T2B?
> 1 votes

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