# Question
Title: Chess960 castling controversies in the 2019 vs 2022 WFRCC, where both are Nepo vs Wesley So
Why did Ian Nepomniachtchi get a replay for the castling issue in the 2019 WFRCC vs Wesley So, but Wesley So didn't get a replay for the castling issue in the 2022 WFRCC vs Nepo?

I mean I know the cases are different:

1. Nepo knew the rules but didn't know how to implement the castling given the rook was occupying the square that the king was supposed to be in.
2. Wesley So didn't know the rules.

But I want to know exactly why the difference implies the results: Nepo gets a replay, while Wesley So doesn't? They both didn't know something and would've done otherwise had they known.

# Answer
> 3 votes
> Nepo knew the rules but didn't know how to implement the castling given the rook was occupying the square that the king was supposed to be in.

According to this article, that is simply not what happened (according to the arbiters, after Nepo appealed the initial ruling).

What happened was the following:

1. Nepo wants to castle kingside, so the king needs to go to g1.
2. The rook randomly started on g1 (and is still there).
3. Nepo moved the rook out of the way in order to move the king to g1.
4. So did not object to this maneuver, but an arbiter spotted it and told Nepo to move the rook.
5. He did so, and then appealed the decision, saying it was impossible to move the king first.
6. The arbiters reviewed the video and determined that he had clearly intended to castle, so the ruling was erroneous. They then ordered the game replayed.

The FIDE Chess960 rules, under "Guidelines II," state that the "game is played in the same way as regular chess" after the pieces have been set up, and characterize the Chess960 castling rules as an "interpretation" of the orthodox chess rules. So we can look at the orthodox chess rules to see how the arbiters justified their ruling.

This is what the orthodox rules have to say about touch-move and castling:

> 4.4 If a player having the move:
> 4.4.1 touches his/her king and a rook he/she must castle on that side if it is legal to do so
> 4.4.2 deliberately touches a rook and then his/her king he/she is not allowed to castle on that side on that move and the situation shall be governed by Article 4.3.1 \[i.e. the player must move the rook if possible\].
> 4.4.3 intending to castle, touches the king and then a rook, but castling with this rook is illegal, the player must make another legal move with his/her king (which may include castling with the other rook). If the king has no legal move, the player is free to make any legal move.

If Nepo touched the king first, or if he touched the king and rook at approximately the same time, then this scenario would fall under 4.4.1, and in fact Nepo would be *required* to castle. 4.4.2 only applies if the player "deliberately" touches the rook first. Presumably, if Nepo had done so, he would have lost the appeal.

The Chess960 rules do *recommend* that players take certain precautions when castling:

> When castling on a physical board with a human player, it is recommended that the king be moved outside the playing surface next to his/her final position, the rook then be moved from its starting position to its final position, and then the king be placed on his final square.
>
> \[...\] To avoid any misunderstanding, it may be useful to state "I am about to castle" before castling.

But these are just suggestions. Players are not required to follow them.

Meanwhile, what happened in 2022 was much more straightforward: Wesley played a move under the mistaken belief that he would be able to castle out of check. By the time the arbiters explained to him that this was not legal, So's move and Nepo's reply had already been made. A move does not become invalid merely because its player misunderstood the rules, even if the player's misunderstanding causes them to blunder. You can tell the arbiter that you (e.g.) "didn't know about *en passant*" until you're blue in the face, but they're not going to void your game on that basis.

---
Tags: fide, chess-variants, world-championship, castling, chess960
---


# Question
Title: Challenge: Create the longest game determined only by the final diagram and move number
The challenge is to create the longest list of half moves whereby an AI could re-create that list of moves perfectly, only given the ending board state and the number of moves.

As example I will first give a short example that does NOT work.

```
[FEN ""]

1. a3 a6 2. b3

```

From that final board state, it is impossible to differentiate it from 1. b3 a6 2. a3.

And a short example that DOES work.

```
[FEN ""]
1. a3 a6 2. a4 a5

```

There is no way to get this board state in exactly two moves other than what was done here.

Scoring will work like this.

1. +1 point per move.
2. +5 points if the game is complete, i.e. the last move in the sequence is checkmate.

This is my best solution so far.

```
[FEN ""]

1. a4 h5 2. a5 h4 3. a6 h3 4. axb7 hxg2 5. Rxa7 Rxh2 6. Rxa8 Rxh1 7. Rxb8 Rxg1 8. Rxc8 Rxf1

```

This would score 21 points: 1 point for each of the 16 moves plus 5 points for ending in a checkmate for black.

Note: Opening pawns moving 2 spaces instead of one is necessary in this particular solution. A 9 turn game where the pawns each move one space per turn would be undifferentiated from an identical game where pawns open with the two space move and then rooks spend an extra turn making their first capture. Also, the game cannot be extended by slipping in Bxg2 at any point in time for White, because it would be unclear, when looking back, when such a move had occurred, since there are several possible turns for such a move to occur.

# Answer
> 8 votes
The current length record is an astounding 57.5 moves (115 half-moves).

```
[Title "Dmitri W. Pronkin & Andriy Frolkin, Die Schwalbe 06/1989, 1st Prize, PG in 57.5"]
[FEN ""]

1. a4 h5 2. a5 h4 3. a6 h3 4. axb7 hxg2 5. h4 d5 6. h5 d4 7. h6 d3 8. h7 dxc2 9. d4 a5 10. Bh6 c1=R 11. e4 Rc5 12. Ne2 Rh5 13. e5 c5 14. e6 Nc6 15. b8=R a4 16. Rb4 a3 17. Ra4 c4 18. b4 c3 19. b5 c2 20. b6 c1=R 21. b7 Rc4 22. b8=R Qa5+ 23. Rbb4 Bb7 24. Nbc3 O-O-O 25. exf7 e5 26. Rc1 Bc5 27. f8=R a2 28. Rf3 a1=R 29. Na2 g1=R 30. Rfa3 Rg6 31. f4 Re6 32. f5 g5 33. f6 g4 34. f7 g3 35. f8=R g2 36. Rf5 g1=R 37. Bf8 Rg7 38. Ng3 e4 39. Bd3 e3 40. O-O e2 41. Rcc3 e1=R 42. Bc2 R1e3 43. d5 Rdd7 44. d6 Rdf7 45. d7+ Kb8 46. Qd6+ Ka8 47. Qc7 Nge7 48. d8=R+ Nc8 49. Rdd3 Rhg8 50. h8=R Rae1 51. Rh6 R1e2 52. R1f2 Rce4 53. Kf1 Bd4 54. Rfc5 Ne5 55. Nf5 Nc4 56. Nd6 Nb2 57. Rbc4 Nb6 58. Qb8+

```

This length record was reportedly beaten in 2017 by Pronkin, Frolkin and Keym (to 58.5 moves) but unfortunately it turned that the longer problem had more than one solution. I do not know if the authors managed to make the problem sound.

Although this problem is not computer-checked, it has withstood human testing for 31 years, so it might as well be considered computer checked by the greatest computer of them all-the human mind.

# Answer
> 5 votes
Addendum 12/14/2023: See Laska's answer down below for a new and improved answer.

---

Such a sequence of moves, where there is only one way to reach the given position on the given number of moves, are called Shortest Proof Games. There are many chess programs that solve such problems.

Long chess problems like this are usually checked with computers using these specially built chess programs, i.e. they are the A.I. that finds the solution you speak of in your answer. These problems have been composed by humans and computer-verified, meaning that there is only one possible solution no matter what you may think.

The longest problem that I know of that is computer verified, often shortened to “C+“, is **41.5 moves** long according to the Die Schwalbe database.

```
[Title "Nicolas Dupont, PG In 41.5, FIDE Olympic Tourney 39 Khanty-Mansiysk, 2010, 3rd Prize"]
[FEN ""]

1. e4 d5 2. e5 d4 3. e6 d3 4. exf7+ Kd7 5. a4 e5 6. a5 e4 7. a6 e3 8. axb7 e2 9. Ra6 exd1=B 10. Rb6 a5 11. h4 a4 12. h5 a3 13. h6 a2 14. hxg7 Ba3 15. f8=B a1=N 16. Bb4 c5 17. Rhh6 Kc7 18. Rhd6 h5 19. g4 h4 20. g5 Rh5 21. g6 Nh6 22. g8=B Nb3 23. g7 Nxd2 24. Bb3 Ne4 25. g8=N Nf6 26. Kd2 h3 27. Kc3 h2 28. Kc4 h1=B 29. Be1 d2 30. c3 Bc2 31. Ne7 Bh7 32. Nf5 d1=R 33. Ng3 Bcf5 34. f4 Nbd7 35. b8=N Qc8 36. Nc6 Qb7 37. Nb4 Bc6 38. Nh1 Rd5 39. Bd1 Kb8 40. b3 Bb2 41. Nc2 Ra3 42. Na1

```

By your system, this problem has a score of 83 points.

The longest computer verified one ending in checkmate that I know of is worth 59 points.

```
[Title "Silvio Baier, Die Schwalbe 4/24/2010"]
[FEN ""]

1. h4 a5 2. h5 Ra6 3. Rh4 Rg6 4. hxg6 h5 5. Rc4 h4 6. g4 h3 7. Bg2 h2 8. Bc6 Rh3 9. Bb5 Rb3 10. axb3 Nf6 11. Raa4 Ne4 12. Rab4 a4 13. d3 a3 14. dxe4 a2 15. Qd5 a1=R 16. Nd2 Ra8 17. Ba6 h1=R 18. Qa5 d5 19. Nf1 d4 20. Nf3 d3 21. Nd4 Rh8 22. f3 d2+ 23. Kf2 d1=N+ 24. Kg3 Ne3 25. g5 Nf5+ 26. Kg4 Nh6+ 27. Kh5 Ng8#

```

Your proof game in 8 moves is computer verified by Jacobi.

# Answer
> 3 votes
In 2023, a new proof game tool exploded into the arena: Stelvio by Reto Aschwanden has broken the record for the longest published proof game to be fully tested. The new record is **48.0 moves**!

```
[Title "Karlheinz Bachmann, PG in 48.0, v Die Schwalbe 104, p. 217, 04/1987, 1st Honorable Mention"]
[FEN ""]

1. Nf3 a5 2. Nd4 a4 3. Nb3 axb3 4. a3 Ra4 5. Ra2 bxa2 6. Rg1 axb1=N 7. Rh1 Nc3 8. Rg1 Nd5 9. Rh1 Nb6 10. Rg1 Na8 11. Rh1 b6 12. Rg1 Ba6 13. Rh1 Qc8 14. Rg1 Qb7 15. Rh1 Qf3 16. gxf3 h5 17. Bh3 h4 18. Be6 h3 19. Ba2 Bc4 20. Bb1 Ba2 21. b3 Na6 22. Bb2 Nc5 23. Bf6 gxf6 24. Kf1 Bh6 25. Kg1 Kf8 26. Qf1 Kg7 27. Qg2+ hxg2 28. h4 Kg6 29. Kh2 g1=N 30. Kg2 Bf4 31. h5+ Kg5 32. h6 Bg3 33. h7 Nh6 34. Rh4 Rb8 35. Rb4 Rb7 36. f4+ Kh4 37. h8=R Nf3 38. Rg8 Ne5 39. Rg5 Ng6 40. Kf3 Kh3 41. Ke3 Kg2 42. Re5 Kf1 43. Kf3 Ke1 44. Kg2 Kd1 45. Kf1 Kc1 46. Ke1 Kb2 47. Kd1 Ka1 48. Kc1 Nh8

```

But in fact, he has done better than that, proving that the first 51.0 moves of Pronkin & Frolkin's 57.5 is sound.

Reto is continuing to improve the tool, and has just released v2.1. How long is Pronkin & Frolkin's PG in 57.5 safe?

Apparently, there is also a candidate for 58.0 in the works, but following a failed 58.5 attempt a few years ago, this new one is being kept secret squirrel until there's more validation. This 58.0 has also been validated for the first 51.0 moves.

(Parenthetically, it's ridiculous that Bachmann's effort back in the day did not merit even a full prize!)

Stelvio can be downloaded from https://www.thbrand.de/stelvio-seite/ (page in German):

---
Tags: problems, records, retrograde-analysis
---


# Question
Title: Is there an en passant opportunity in this position?
I am trying to create a scalable chess move generator in python for my chess engine. My legal move benchmark comes from "python-chess" library. My move generator generates an en passant opportunity at **f6** by playing **f7f5** on **r3r3/3k1ppp/p5Q1/PP2P3/b6b/2RP4/2n1K3/1NB1n3 b - - 8 44**, but python-chess library does not generate an en passant opportunity.

From what I understand about En Passant, my move generator is correct and python-chess library is incorrect. Is my understanding correct or am I missing something?

```
Testing FEN: r3r3/3k1ppp/p5Q1/PP2P3/b6b/2RP4/2n1K3/1NB1n3 b - - 8 44
        My Move Generator:: r3r3/3k2pp/p5Q1/PP2Pp2/b6b/2RP4/2n1K3/1NB1n3 w - f6 0 45
        Python-Chess library generator:: r3r3/3k2pp/p5Q1/PP2Pp2/b6b/2RP4/2n1K3/1NB1n3 w - - 0 45
FAILED!

```

```
[FEN "r3r3/3k1ppp/p5Q1/PP2P3/b6b/2RP4/2n1K3/1NB1n3 b - - 8 44"]

```

# Answer
So the situation is that there would be an en passant opportunity, except it's not a legal move because the pawn on e5 is pinned. Both choices are functionally the same as the tree of legal moves from the position defined by each FEN is the same. Both ways will work perfectly fine, as it's in the end the same position.

I guess the chess programming Wiki is the closest we're going to get to a consensus description of FEN, and it says:

> The en passant target square is specified after a double push of a pawn, no matter whether an en passant capture is really possible or not.

That's pretty clear -- it's what you do.

That's surprising to me. Following the footnotes, there is a comment by the original author of FEN calling it a mistake, and in general there are a lot of people unhappy with the choice in the standard (it actually says to record *all* double pawn moves in the en passant field, even if there's no adjacent pawn -- e.g., after 1.e4).

In the end it's a tradeoff between checking for the existence of a legal en passant move at the time of generating the FEN versus at the time of using it. In my opinion it would be nicest to check when generating, so what PyChess does. But what you do is what is written down in the standard and probably in common test sets.
> 5 votes

---
Tags: engines, python, en-passant
---


# Question
Title: Why did Magnus Carlsen not play the World Chess Championship in 2023?
Why did Magnus Carlsen not defend the 2023 world chess title? He claimed it was too easy, but is there a deeper meaning/reason that he chose not to participate?

# Answer
> 23 votes
It's not that Carlsen finds the World Chess Championship too easy, but rather that he is losing interest in classical chess as a whole. The reason for that is opening preparation dominates classical chess, which means spending a lot of time looking for new ideas to gain an opening advantage. Carlsen does not find this very interesting, because it pits your computer against your opponent's computer, as opposed to your chess-playing skill against their chess-playing skill. The World Chess Championship is especially harsh on this, because the opponent will have serious support in the opening (with dedicated seconds), which means you need to do the same to be competitive.

You can see secondary effects of this fatigue from Carlsen occasionally playing moves like 1. a4 or 1. e4 g5 (as Black), to get out of well-explored opening territory as quickly as possible.

# Answer
> 14 votes
Magnus himself stated at the end of 2021 after the Nepomniatchi -Carlsen match that he did not have the motivation to contest another challenge unless it was Alireza Firouzja as the challenger.

FIDE reported it thus

Chess media reports from chess base here and another here

News media reports from The Guardian and from CNN.

So, these are Magnus’ own opinions and FIDE and the media reports at the time. I am unaware of other speculation or opinion in the open media.

# Answer
> 0 votes
The deeper reason for Magnus deciding not to play WC may be that he tries to use his influence to bring change to the WC competition format.

# Answer
> -1 votes
I believe that Magnus decided not to compete in the 2023 World Chess Championship because there was more to lose than to gain. Everybody would be expecting him to win and I think that was a little too much for Magnus to handle even though he is arguably the greatest of all time and would probably win. If he didn't win everybody would think that he is falling off and may not be in his prime anymore. I hope this makes sense and hopefully helps you understand why he decided not to compete.

---
Tags: world-championship, carlsen
---


# Question
Title: Tools for automated notation: webcam movie to PGN
Sometimes during blitz games over the board, or when in zeitnot, it gets very difficult to annotate them.

I've seen several software / hardware to help in writing the notation, even one that's FIDE approved; these require that you repeat the moves on the device. Hardly faster than pen and paper, just as prone to errors, plus you risk typing the wrong move and wasting even more time.

DGT makes a board that will do this automatically, but it will only work with its pieces, and starts at 400€, double that for tournament boards. Some independent projects are available such as usb chessboard 101, or voice controlled chess robots, Chess board step sequencer. Additionally some open projects are available that even move pieces (or gigantic pieces).

I have a playoff tonight, and the tournament rules dictate shorter and shorter games until there is a winner. Hence I thought about shooting a movie of the board should we lose track. But then my programming background kicked in and I thought "there must be some software that can process a movie and write the PGN".

I searched everywhere, and found nothing.

1. Does any such thing exist (webcam/video to pgn converter)? A prototype maybe?
2. Has anyone attempted such a feat and shared their research?
3. Are there obvious limitations that make this project unlikely to succeed?
4. Would you buy it if it existed?

# Answer
It is clearly interesting and relevant to automatically record chess games (live boards are more or less tackling the same problem). As far as I know, there is no software for this purpose that exists today. To solve this problem, I think that the "simple" case should be as follows.

1. The chess board should be filmed from top-down to get a two-dimensional view. (Motivation: filming in a three-dimensional view would cause problems because of a skewed view and pieces that will block the view for other pieces behind them. Also, different 3D-views are possible which would counteract a clean procedure.)
2. The film should be manually edited to capture "clean board" moments and remove moments when the two players' hands or heads are blocking the view.
3. The image processing algorithm on the software side should detect changes on the board and record them as moves. It should also auto-rotate and transform the image to detect the board orientation and thereby the coordinates.
4. The software should use the starting position to "memorize" every piece type and then use these for the image recognition during the game. Probably, some clever tricks can be written to solve the problem of piece recognition in a smart way.

A quick Google search with the search string

> chess game image processing

returned this interesting article

All in all, it should be realistic to implement this type of software. Yet it might be cheaper for a human to do the same work (transfer moves from a video clip to a computer).
> 5 votes

# Answer
It's 2019-12 now and 5 years after the original question.

1. Does any such thing exist (webcam/video to pgn converter)? A prototype maybe?

see
2. Has anyone attempted such a feat and shared their research?

Yes - so far I found some 35 research papers and some 10 open source solutions and one commercial offering

2.1 http://wiki.bitplan.com/index.php/PlayChessWithAWebCam/Papers

2.2. http://wiki.bitplan.com/index.php/PlayChessWithAWebCam#Open\_Source\_Projects

2.3. http://wiki.bitplan.com/index.php/PlayChessWithAWebCam#Commercial

http://wiki.bitplan.com/index.php/PlayChessWithAWebCam is another project aiming at the goals stated by you. The project was started 2019-10-15 and in a few hours I already found a lot of resources e.g. this Question Some two months later I have updated my answer (see links above)
3. Are there obvious limitations that make this project unlikely to succeed? I can only answer from my own experience with a similar project I did 31 years ago see http://wiki.bitplan.com/index.php/MagneticSensorChessBoard1987. At that time i tried to create a chess board that would detect moves. I used magnets in the wooden pieces and reed contacts. The key to success was using a chess engine that new "the rules" to be able to concentrate on movements alone and not having to detect individual pieces. As outlined in an answer above promotions to non queen pieces might be one of the edge usecases that are difficult. Detecting the motion of pieces via picture differences is a well understood problem.

Chess engines and UCI compatible GUIs are also available these days. So the problem is more an integration problem these days then solving the individual detail issues.

A major obstacle is the difference between a "prototype" and a product. See e.g. http://www.nandanbanerjee.com/files/ICCVR-08AUG12-011%20paper.pdf

a paper that is even older than this question but far from a product that you can buy at a reasonable price.
4. Would you buy it if it existed?

Yes. When I bought a new chess board a few days ago I was looking for one that could record moves and it was still around 500 EUR. As it looks the hardware cost will be well below 150 EUR these days including a decent chess board and pieces.

The software might well be opensource and free (as in free beer) soon. I'll update this answer accordingly.
> 7 votes

# Answer
In order,

1) Not to my knowledge

2) Not to my knowledge

3) There are several things that make this sort of project non-trivial, even difficult. Not the least of which is following the piece, differentiating it from a hand gesture, for example. Also determining when the move stopped would be an interesting question for computer vision to solve. These kinds of problems have been solved in other situations, but not with 100% accuracy, and certainly not at prices that are even close to being competitive with the DGT board.

Then there's the question of where the camera could be positioned. Directly overhead would offer the best view of the board, making it easier to determine the square with precision. But wherever the camera gets placed, there's a distinct probability its view will be obstructed by one of the players, either leaning over the board, reaching for the clock, or simply gesticulating.

4) Not unless it was really cheap. And I don't expect it would be. My reasoning is simple. As time controls shorten, the quality of the game lessens, to the point where it's no longer interesting to me
> 5 votes

# Answer
That would be a rather complex task. Maybe a reasonable first step is to look into recognizing FEN position from a single image - for which more resources exists, for example:
> 4 votes

# Answer
I wrote this software. It contains webcam AI for move recognition, connected to Arena GUI.

https://www.youtube.com/watch?v=APkoE1UDKj0
> 4 votes

# Answer
I worked on the chess tracking project **8x8cam** within image processing course in 2013 at FING UdelaR.

Then in 2014 other students created a better version for Android named **chesstrack**. Under it's web you can find videos and link to the code they used.

I would love to see a finalized app of this project idea I had for years. So if there is some news about this please leave a comment.

Answering your pointed questions:

1. Does any such thing exist (webcam/video to pgn converter? A prototype maybe?

Apart from my project 8x8cam and chesstrack, I have recently found a project named ChessCam. All of these projects are Open Source and only need to be named as resource if you create a new project from them.
2. Has anyone attempted such a feat and shared their research?

Yes. You can see such on previous question's answer.
3. Are there obvious limitations that make this project unlikely to succeed?

The hardest part I believe is to make the software work no matter how the camera is placed and independently of the illumination. And also to work on fast paced games and work with the hand occlusions when the game is being played, in order to detect correctly the move done.
4. Would you buy it if it existed?

Definitely yes.
> 3 votes

# Answer
**Edit:** promoting to anything different than queen will make everything explode. It will also be very hard to support this (my program for Part 2 supports underpromotion, but storing the info of Part 1 purely by reading pixels is a nightmare).

**Edit2:** I just noticed you mean real board chess to PGN, so this is all useless and I will most likely delete my answer.

## Part 1: storing the squares using pixel readers

It is totally possible, the steps needed would be:

1. change the set up of the board so it highlights the last move (prefereably *not* just the border)
2. write a program that reads pixels on given (x,y)
3. make it read about 5+ pixels on each square (so it is impossible for the cursor/piece to cover all the pixels to be read)
4. convert the HEX to RBG, then give a **range** of accepted values of what we deem to be considered close to the "last move" color
5. save the moves on an array with a format `["h1-h8", "e4-e5", ...]` just the initial and ending squares (order **unimportant**)

**Note:** from here we can't really know from which square was the initial/ending position, but there are only 2 posibilities and only 1 of them is legal.

I have written simple pixel-based macros/bots for RPGs games in C#, I can guarantee this is not *that* difficult, given that:

1. the cam is static (so the x,y values don't get messed up)
2. you previously know the background color or you can set it up before playing

Basically, it is best if the game is played online and you are recording directly from the screen.

> Sorry, no program avaiable for part #1

---

## Part 2: exporting that list into PGN

To turn this list into a real PGN, you can use a program I wrote in JavaScript that records moves, and one of the functions `moveCaller()` you pass two squares positions and it searches the `final_pos` in the legal moves of `initial_pos` and if there is a match then it calls `makeMove()`. So we can call it twice `e5 to e4` and `e4 to e5` and I guarantee it will ignore the illegal one.

1. download the project (direct link .zip)
2. uncompress the `.zip`
3. change the JavaScript of the `index.html` file with this:

'

```
$(function(){
    var i, len, arr, temp, m_board;

    m_board=IsepicChess.initBoard({name : "main"});

    arr=["e4-e2", "e7-e5", "f3-g1"]; //is ok for the initial and final squares to be swapped

    for(i=0, len=arr.length; i<len; i++){
        temp=arr[i].split("-");

        //one of the two following lines will silently fail
        m_board.moveCaller(temp[0], temp[1]);
        m_board.moveCaller(temp[1], temp[0]);
    }

    m_board.refreshBoard();
});

```

.4. copy the move list and add some PGN headers above it like `[WhiteElo "2400"]` etc.
> 1 votes

# Answer
Joey Meyer wrote and built "Raspberry Turk":

> The Raspberry Turk is a robot that can play chess—it's entirely open source, based on Raspberry Pi, and inspired by the 18th century chess playing machine, the Mechanical Turk.

This goes beyond the OP's question because it also incorporates (a) the engine to calculate responses and (b) a robotic arm to make the engine's moves on the board.

But it answers the OP's question because one component of Raspberry Turk includes an overhead camera and a machine-learning component to learn how to convert what it sees on the board into a PGN representation of the board.
> 1 votes

# Answer
Firstly, great post. I have been surveying this issue recently and the answers here are a great source of information. I have found an excellent free app for Android and iOS called KnightVision. It is relatively new. It was trained on various chess sets. It even managed to properly recognize my hand-crafted pieces which are not identical to the Staunton standard. It works well, although to be on the safe side, it requires a separation of about 3 seconds between each move on the board. So be gentle when swapping pieces, which is something that is usually done quite quickly. It also has a web page, where after logging in you can see the game PGN that you can copy and export to any chess engine for studying. It also has some analysis on the website itself. https://www.knightvision.io/
> 1 votes

# Answer
I'm the developer of ChessCam, an open-source web app to digitize your chess games. It relies mainly on running object detection models (yolov8) in the browser.

Try it out here: https://www.chesscam.net (code at https://github.com/Pbatch/CameraChessWeb).
> 1 votes

# Answer
*I won't be answering the question, because I don't know if there's a software out there. I'm just saying how I think that's how to do it, I don't know for sure, so...*

---

Okay first you need to make sure that the video is recorded from a chess software, not a live tournament, just to make your job easier.

You need to convert the movie to images

`ffmpeg -i foo.avi -vsync 0 -vf select="eq(pict_type\,PICT_TYPE_I)" -s WxH -f image2 foo-%03d.jpeg`

That was easy, now the hard part, you need to start doing image processioning, for that, the most powerful is OpenCV.

For that, there are several techniques, I'll give you the links so you can read them.

It is complicated but simpler than you think, because you only need to know what is the starting position, loop through all the images and see the difference. Take a look at OpenCV docs you'll find tons of materials on that subject.

---

*Oh by the way, what you're asking for is done already, but not using software as far as I know, there's an old project that was coded using Pascal, cameras placed over the board, robots do image processing and make a move. Nowadays many robots play chess.*

*You could buy an Arduino uno, and its light censor, it will detect the white pieces and the black pieces, some coding and it will play chess. :)*
> 0 votes

# Answer
Squareoff is making another board at 200$. Expensive but not extortionist. They say it will be available March 2021. Automatically moves pieces too. Details. Has Blitz mode but may not be so good for it. May not allow more than one user per board but plays through chess.com and maybe lichess.
> 0 votes

# Answer
I use the Monroi Chess Notation Device for all my chess games and it is basically an electronic board.
> -1 votes

---
Tags: software, tournament, notation, pgn
---


# Question
Title: What's the easiest way to hold this 4 vs 3 pawns on same side rook endgame?
After having been under tremendous pressure due to a mistake in the middle game and with only 30s on the clock, I was very relieved to find a way to liquidate into this endgame, which I knew was a theoretical draw.

```
 [FEN "8/5pk1/R3p1p1/8/7p/7P/3r1PP1/6K1 w - - 0 34"]

```

Long story short: I managed to lose this endgame. Not due to my time-trouble, but because I didn't manage anything of the following: active counterplay/defence using my rook, cutting off his king, trading pawns,.... He just slowly advanced his king, shielded by his pawns and due to his active rook and restricting pawns I could never really free myself.

How to hold this endgame? The engine claims that every single legal move from White (except the ones immediately losing material and g3) is -0.2 or -0.3... So apparently, even though Black is more active than in other 3-vs-4-scenarios, White doesn't seem to need precision from the start. What's the defence plan / setup that White should follow to facilitate the draw?

# Answer
The general drawing technique for rook endings with 4 vs 3 pawns on the same wing is:

1. Avoid Rook Exchange
2. Exchange pawns
3. Advance h-pawn to h4

Idea is that with a white pawn on h4 Black will not be able to avoid pawn exchanges when they advance their pawns. In your diagram this is already impossible so the defense will be difficult. In future I suggest trying to avoid defending a position like this.

4. Strive to prevent the advance of the e-pawn.

Use moves such as Ra4 and f3 to prevent ..e4.

5. Look to cut his king off from his pawn and/or attack his rear pawns with your rook.

This becomes possible when White moves to force through the advance of the e-pawn.

Many endgame books have a section on this ending. A model game when the h-pawn cannot advance is Korchnoi - Antoshin 1954. Korchnoi's book `Practical Rook Endings` covers this ending in detail.
> 4 votes

---
Tags: endgame, theory, draw, rook-endgame
---


title: Does elo rating have a limit?

text:
# Question
Title: Does elo rating have a limit?
The highest Elo rating to date is 2882, which belongs to Carlsen, while the last Elo rating of Kasparov is 2851. Could I have an Elo rating of 2950 or maybe 3000? Does the Elo rating have a limit?

# Answer
> 12 votes
No, Elo ratings have no theoretical limit. If Alice scored 76% against Carlsen (rating 2853) consistently, she would stabilize at a rating of 3053\*, and if Bob scored 76% against Alice, he would stabilize at a rating of 3253\**, etc. There is no theoretical end to this sequence. However, consensus seems to be that in practice a perfect player would have a rating somewhere in the 3000s.

\*Assuming Carlsen performed well enough against other people that his rating stayed at 2853

\**Assuming Alice performed well enough against other people that her rating stayed at 3053

# Answer
> 7 votes
Yes ratings have a limit for chess, go, etc; as ratings go higher , the proportion of perfect games will increase and therefore if chess is a theoretical draw, the rate of draws will also increase (assuming most games are played against players of similar rating.) Once 100% draws are reached there is no better rating. This is borne out by the graph here which if extrapolated indicates that 100% draws would occur for engines at a rating of about 5200. Similar reasoning obtains if chess is a win or loss for white, namely that once perfect play is reached in 100% of games played, all white games are won and all black are lost or vice versa, again assuming play against similar beings. Even if one plays against dissimilar beings, an asymptote is reached in the calculation of elo points won per game; as ones rating rises , it is harder and harder to win points against lower rated rivals, again enforcing an upper bound. It is also clear that a perfect player will not have an inifinitely high rating since once in a while an imperfect player will play a perfect game, reducing the perfect players expectation from 1.0 to 1-epsilon thus enforcing a finite rating. (Look at the ratings difference curve (expectation as function of ratings difference) and you will see an asymptote to 1.0).

# Answer
> 0 votes
Elo is a relative scale that measures the winning probability between two players. The scale itself is arbitrary and there are many variations but here is no upper limit as such if the game is complicated enough and has enough room for continued improvements in game play.

In the game of Go a top professional has Elo rating around 6800 (KGS system), but a good AI engine can reach far beyond that. For example the Leela Zero Go engine has a current rating of 11,000+ (May 2018, after training on 7.5 million self-played games), and it is still improving. The game itself has enough complexities so how much further we can push up the Elo rating will be limited by how much computer resources were used to train the AI.

# Answer
> 0 votes
There is no theoretical maximum for the Elo rating.

There is, though, a theoretical maximum gap between the top rated player and the second which, in the first implementation, was 700+ point (when the difference of ratings between players was that or more the expected result was 1.0 so that winning doesn't earn you points).

Another factor to take in consideration is that the Elo rating is **NOT** a measure of absolute strength but a measure of performance relative to the ratings of the players. Since the strength of the players follows what in statistics is called a normal distribution, this was Elo's basic assumption, the probability to have a player rated at a rating R is never zero no matter how big R is, which means that if the total pool of rated players increases you automatically have higher top ratings simply by the law of large numbers. This is the basic reason (but there are are factors concurring) why the average rating of the top 10 players has increased over time: simply because the number of rated players has increased manifold.

---
Tags: rating, elo
---


# Question
Title: What is the result if a player has insufficient material and the opponent plays two illegal moves?
Suppose player X has only a king. Their opponent has played two illegal moves during the game. Is it a draw or does X win?

# Answer
> 5 votes
Draw by §7.5.5. (Analog is fallen flag, draw by §6.9.)

> 7.5.5 ...However, the game is drawn if the position is such that the opponent cannot checkmate the player’s king by any possible series of legal moves. (Source: FIDE Laws of Chess)

---
Tags: rules, draw, illegal-move, winning
---


# Question
Title: What are "monochromatic" retrograde analysis problems?
What does it mean when a retrograde analysis problem is qualified as being "monochromatic" ?

# Answer
> 9 votes
"Monochromatic" (or "monochrome") is a popular fairy condition with nearly 450 examples in the PDB database: https://pdb.dieschwalbe.de/overview.jsp?expression=K%3D%27Monochromatic%27

It is frequently used in retrograde analysis, but can appear with purely forward stipulations having no retro content.

Each piece move must end on the same colour square it began. This is a comically severe restriction:

* Knights cannot move at all
* Pawns can only capture (after any initial double step)
* only K-side castling is legal.

On the other hand, en passant is fine and indeed often exploited in problems to help a pawn promote.

Here is a simple but fun example, by A.Buchanan 1991:

```
[Title "Show a promotion route, indicating units captured. Monochromatic."]
[fen "3qk3/6p1/8/8/8/8/1P1P1P2/4K3 w - - 0 1"]

```

Solution at https://pdb.dieschwalbe.de/P1339843

\[Note that solutions in PDB use German piece names, so KQRBNP translates to KDTLSB (König, Dame, Turm, Läufer, Springer und Bauer). White/Black translates to w/s (weiss/schwarz). Finally, if there is ever castling, kingside & queenside translate to k & g (kleine = short & grosse = long).\]

In most problems, "checks are fairy". This means that a King is only in check by enemy units standing on same-colored square, when capturing the King would be a monochromatic move. So that e.g. the two Kings can happily be in contact.

The monochromatic constraint has been used several times in the popular Sherlock Holmes book by Raymond Smullyan. However in Smullyan's compositions, checks are not fairy: the kings could not be adjacent.

Another variant relies on the concept that castling is considered to be a king's move (with the rook just a "passenger") In this context, queenside castling is ok.

Monochromatic allows some deep compositions. For example, here's one by the renowned French composer Thierry Le Gleuher:

```
[Title "What unit captured Ng1? Monochromatic."]
[fen "1N4B1/2p2p2/2Q3k1/p2p1RPp/P4P1b/7P/2PPPrrK/8 w - - 0 1"]

```

Solution sketch at https://pdb.dieschwalbe.de/P0001761.

Note that wKh2 is not considered to be in check. This won the 1st prize in diagrammes for 1989 and appeared in the FIDE Album 1989-1991.

See also: Max number of promoted units on the board in a monochromatic game

# Answer
> 4 votes
This type of problem is defined in the book "*The Chess Mysteries of Sherlock Holmes*" by Raymond Smullyan as being retrograde analysis puzzles where the pieces have the additional rule that they may not change color. That is, a piece may not move from a white square to a black square or vice versa.

This has a number of consequences:

1. Knights may not move
2. en passant is allowed, so in that particular case a white squared piece can capture a piece on a black square
3. Castling is only possible on the king side because queenside castling involves the rook changing color of square.

Here is an example:

```
[Title "What color is the pawn on g3?"]
[fen "4k3/8/8/8/1K6/6P1/3P1P2/8 w - - 0 1"]

```

The logic is as follows:

1. The white king started on e1, so must have castled kingside to escape to the center of the board
2. If the pawn on g3 is white then it must have come from a dark square, h2. But in that case the white king could not escape from the castled position.
3. Therefore the pawn on g3 must be a black pawn

---
Tags: chess-variants, retrograde-analysis, monochromatic
---


# Question
Title: Why do certain chess combinations start with moves that can be intuited before understanding the full sequence?
There seems to me to be a strange phenomenon in chess where a combination exists and pays off if and only if you make a series of accurate moves without any deviations. Often times you can find many of the correct moves in that series without having seen the point of the combination, or the entire combination. This strikes me as odd. Why should this be so? If those moves are only good if you complete the combination, why then do they jump out at you intuitively, even if you can't see the whole combination?

# Answer
> 1 votes
As a 100% intuitive player, I try to answer:

Combinations do not come out of the blue. There must exist objective preconditions (say, a lead in development). Even if I can't calculate further than half a move (in fairness, I can, but my brain hurts if I try), I "see" the move. Case in point: I was analyzing a training game with a kiddie and his trainer. He said: You were lucky, the engine gives a move here that annihilates you. Me, in a nanosecond: e5. He: How did you... Me: Easy. You gave the move away by it's pure existence, in Sicilian Bxf6 gxf6 structures, it is *always* e5! Of course I couldn't analyze e5, it wasn't even that tempting. But intuitive players know thousands of patterns, and the case you describe is simply the pattern checker throwing a "Go!".

Compare also to Alpha Zero. It doesn't do concrete "calculation" at all, it only checks patterns (that's how neuronal nets work). Still, it's a tactical monster.

# Answer
> 1 votes
The initial move or moves of a combination and understanding the full sequence, whether the combination is a blunder or a winning one, are not connected.

**ALL** initial moves of this sort are the rest of pattern recognition or a kind of intuition. At least for players who have progressed to the early beginner stage where some chess related pattern recognition has been developed. Complete beginners may still make moves that are almost random.

Understanding the full sequence is a matter of correct calculation. The two are not connected. Not understanding the full sequence, a kind of "hope chess", leads to chance results. You may get lucky or your move may be a blunder.

Here is an example from the "HangingPawns" YouTube channel of a player getting lucky. He thought Qh8+ at the end of the combination would be mate, overlooking the black knight on g6, only to be rescued by the possibility, spotted at the very last moment, of Bxf7#.

Some of HangingPawns commentary added in the comments, but it's worth watching it on his channel for the full emotional rollercoaster.

```
[Title "Getting lucky"]
[fen "1nbqrbk1/3r1ppp/p5n1/1p3p2/1P1NP3/PBQ5/1B2N1PP/3R1RK1 w - - 0 1"]

1. Nxf5 Rxd1 2. Nh6+ gxh6 {Oh! There's a knight on g6! There's a knight on g6! Nooo! Wait!} 3. Bxf7# {It does work. I have Bf7. ... I didn't see Bf7 before I played Nh6. I didn't see that. Luckily it did work} (3. Qh8+?? Nxh8)

```

---
Tags: psychology
---


# Question
Title: If 2 rooks are on the same Rank how to record the move if one rook moves towards the other?
Like for example a rook is on f1 and another is on a1 and I move the rook on f1 to b1 what would I write?

```
[Title "Notation to move the f-Rook to b1?"]
[FEN "4k3/8/8/8/8/8/8/R4R1K w - - 0 1"]

```

# Answer
With rooks on **a1** & **f1**, you would write: **Rfb1**.

With knights on **a1** & **a5**, you would write **N5b3**.

With knights on **a1**, **a5** & **c5** :), you would write **Na5b3**.

It's all described here very well: https://en.wikipedia.org/wiki/Algebraic\_notation\_(chess)
> 6 votes

# Answer
To move the f-Rook to b1: `Rfb1`, where R is Rook, f is the starting file (or ranks in some cases) and b1 is the final square. 'f' is written to denote which Rook moved since both Rooks are on the same rank.
> 1 votes

---
Tags: notation
---


# Question
Title: Does chess engine Stockfish remember already performed calculations within one session?
Let's say I call Stockfish via

```
> position fen rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
>'go movetime 500';

```

Now, after Stockfish has finished the analysis, what happens if I call stockfish again with the same position?

```
> position fen rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
> go movetime 500

```

Will Stockfish build on the already performed analysis and simply go deeper? Or will it start the analysis anew?

# Answer
> 5 votes
Yes, Stockfish will go deeper if the hash is large enough to make a difference. The default value is 16 MB which is not a lot. After increasing the hash you likely see that the second time the search depth reached after 500 ms is higher than the first time you let Stockfish calculate.

```
setoption name Hash value 256

```

# Answer
> 2 votes
One UCI session you mean? To make reproducible experiments or test above, you can compare/contrast multiple calls, by using the UCI purge hash.

"setoption name Clear Hash"

---
Tags: engines
---


title: Max percentage of mating pieces

text:
# Question
Title: Max percentage of mating pieces
In the newest SCHWALBE, positions are given where *any* piece on the board can give a check (any being surprisingly high). A quick dabbling seems to prove that it is *not* possible that any piece can mate. (Only try is something like Kf3 Qg2 - Kd5 Qc6, but how to take the flights?)

Thus the next best would be "Find a position where a maximal fraction of pieces can mate". (Of course we suppose either side may have the move.) What is your record attempt?

EDIT! "Can mate" is unprecise since in the case of a battery it is a priori unclear who mates (you can argue for both positions). I usually go for "only a piece that checks can mate", but in this special case (as you can already infer from the first paragraph) I prefer the other interpretation and formulate more precise "Find a position where a maximal fraction of pieces can make a move (or more) that delivers mate".

```
[FEN "8/8/8/8/1Q6/K7/7q/k7 w KQkq - 0 1"]

```

Example: 50% of all pieces can mate

# Answer
It's easy to get 16/17 = 94.1%

```
[FEN "4B3/4Q3/3QQQ2/1N2B2N/4k3/1Q5Q/3PKP2/2R1Q1R1 w - - 0 1"]

```

On further thought that's not legal for lack of a previous Black move. This should be fixable, but meanwhile I see that 19/20 = 95% is possible:

```
[FEN "8/3Q1Q2/3Q2R1/1Q3N2/n3kBQ1/1B6/n2RKP2/1n2QQQN w - - 0 1"]

```
> 3 votes

# Answer
26/28, 92.86%, maximum.

```
[FEN "5k2/Q1Q1RBNQ/1N1B1Q1Q/1QN2Q2/1qn2q2/1n1b1q1q/q1q1rbnq/5K2 w - - 0 1"]

```
> 0 votes

---
Tags: problems, puzzles, records
---


# Question
Title: What is the best way to improve Crazyhouse or Bughouse skills?
I have been playing Chess variants for a while now, and I would like to know how to improve my skills in bughouse and crazyhouse. Does anyone have any tips or strategies that would apply to either? Any input would be very helpful.

# Answer
> 3 votes
Since there isn't much material out there to study, the best way is to play with better players. Of course, studying tactic problems is great for chess and the variants. FICS (free internet chess server) is probably where the best Siamese (bughouse) players are.

It helps if you have some opening systems worked out (since in Siamese being ahead on the clock can be crucial).
Published tips are here: http://www.freechess.org/Help/HelpFiles/bughouse\_strat.html https://www.chess.com/blog/Sorsi/advanced-bughouse-tips

# Answer
> 0 votes
Bughouse is a very tactical game and you can practise bughouse tactics by doing puzzles on this website: https://bughouse.ca/

It should also help for crazyhouse.

(disclaimer: I'm one of the developpers of this website)

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


title: How to face an engine?

text:
# Question
Title: How to face an engine?
I usually judge a human opponent seeing his rating and decide my move considering his moves while I face him in a chess board. If his or her rating is greater than me by around 100, I pay much concentration and a degree of honor to my opponent. In the case of my human opponent, I sometimes may get blunders if he is even a GM, and it may lead to a win for me. But if the opponent is an engine, hopefully, he should make no mistakes or blunders. So, What would be the perfect approach for me while I know that the rival is a computer so that I feel no pain at all if I lose the game?

# Answer
The answer is the usual: Do you feel humiliated if a cheetah outruns you? An elephant beats you in a weight-lifting contest? I couldn't care less if a computer beats me at chess (they already did 40 years ago, even if I am a FM) and still wait for the first "general" AI. It's a bit pointless to play a computer anyway (unless you don't do it for the win, but for other things - checking your repertoire or whatever, there are enough possibilities).
> 4 votes

# Answer
I am not quite sure, if this answers your question, but no human will ever win against an engine, that is actually trying.

Feeling bad for losing against a computer at chess, is akin to feeling bad, for losing to a calculator at calculating.
> 0 votes

# Answer
I think it is not a good idea to take into account the level of one's opponent when playing chess. Possibly it helps scoring some wins (by doing things like avoiding tactical complications if playing weaker players and seeking them out against stronger players, in order to increase P(blunder)), but it is equally possible that knowing the opponent's rating leads to either undue self-doubt or arrogance, depending on sign of the rating differential, and thus to weaker play; but I digress.

State of the art chess engines are pretty much unbeatable for humans. However, they strictly play the board, not the opponent, and therefore chances of a draw might be higher than against a top human (if one is oneself below top human level) if a draw is all one aims for. I think very strong humans can expect to occasionally draw against Stockfish even when it runs on top hardware, maybe unless specialized settings are used that make the engine work to avoid draws.

Other than that, playing weaker engines can still be fun. I personally enjoy playing against Leela Zero set to run without lookahead (one playout only) in the Nibbler GUI, with the current T2 network. With these settings, it plays an incredibly instructive positional game that should slowly crush even strong humans, but makes occasional tactical mistakes that give strong players a real chance to win. Stronger humans can adjust this recipe by giving it some limited lookahead, weaker ones can use one of the weaker networks.
> 0 votes

# Answer
**Play correspondence chess**

Now you can use your own engines too, so you still only lose if you make a mistake (and win if your opponent makes a mistake).

PS: Engines can and do make mistakes.
> 0 votes

---
Tags: engines
---


# Question
Title: How to convert scid.eco file in scid _vs _pc to pgn file
Is there any tool or option in scid\_vs\_pc to convert the scid.eco file in bin/data directory to useful pgn file there is some code in gethub named eco2pgn.py but i cant figure out how to use it

# Answer
> 0 votes
Install python, then run the script from command line.

```
python eco2pgn.py scid.eco > your_scideco.pgn

```

`eco2pgn.py` and `scid.eco` should be in same folder.

# Answer
> 0 votes
This is not a direct answer, but if you simply want a file of ECO data in PGN format then there is one freely available with pgn-extract on this page: https://www.cs.kent.ac.uk/people/staff/djb/pgn-extract/

# Answer
> 0 votes
The conversion script included with ScidvsPC, eco2pgn.py would need to be updated to run in python3. See https://sourceforge.net/p/scidvspc/tickets/63/ for the changes (easily made).

# Answer
> 0 votes
I have added an updated version of eco2pgn.py that works with Python 3 here https://sourceforge.net/p/scidvspc/tickets/63/

---
Tags: pgn, scid, eco
---


# Question
Title: Max number of promoted units on the board in a monochromatic game
A whimsical question just occurred to me. I think I have an answer, but I thought I would share it here as a puzzle.

What is the maximum number of promoted units that can appear simultaneously on the board in a monochromatic game?

(with reference to What are "monochromatic" retrograde analysis problems?)

Please find a game to illustrate this.

# Answer
> 3 votes
It takes four captures to promote a pawn in monochromatic. Only 15/16 of each sides' pieces are capturable. Thus, in theory, each side may only promote three pawns at most, or a total maximum of six combined.

And it is indeed possible, albeit tricky. Utilizing en passant to change a pawn's lane color is a crucial aspect.

```
[FEN ""]

1. a4 a5 2. b4 b5 3. bxa5 bxa4 4. g4 g5 5. h4 h5 6. Rh3 Rh6 7. Rb3 Rb6 8. axb6 axb3 9. bxc7 bxc2 10. cxb8=N Qb6 11. d4 Qc5 12. dxc5 d5 13. cxd6 Bf5 14. Bf4 Bh7 15. Bh2 gxh4 16. gxh5 Ra6 17. Ra3 cxb1=N 18. dxe7 Rg6 19. Rg3 hxg3 20. hxg6 gxh2 21. gxh7 f5 22. e4 fxe4 23. f4 exf3 24. Be2 fxe2 25. exf8=B hxg1=N 26. hxg8=N exd1=Q

```

# Answer
> 1 votes
I want to complement @RewanDemontay's accepted answer.

It's clear that the number of promotions can't be more than 6, because each promotion involves 4 captures, plus the promoted unit itself which is not eligible for captures. (32-2)/(4+1) = 30/5 = 6.

One can divide the pieces into 4 sets of 8. How many promoted pawns can share the same square colour as their king? There are several patterns possible from simple counting, but only two can work out:

**Case 1**

|  | White dark sq | White light sq | Black light sq | Black dark sq |
| --- | --- | --- | --- | --- |
| King | 1 | 0 | 1 | 0 |
| Promoted pawns | 1 | 2 | 1 | 2 |
| Captured units | 6 | 4 | 6 | 4 |
| Captured e.p. | 0 | 2 | 0 | 2 |
| Total | 8 | 8 | 8 | 8 |

**Case 2**

From counting we get:

|  | White dark sq | White light sq | Black light sq | Black dark sq |
| --- | --- | --- | --- | --- |
| King | 1 | 0 | 1 | 0 |
| Promoted pawns | 2 | 1 | 2 | 1 |
| Captured units | 3 or 4 | 6 or 7 | 3 or 4 | 6 or 7 |
| Captured e.p. | 2 or 1 | 1 or 0 | 2 or 1 | 1 or 0 |
| Total | 8 | 8 | 8 | 8 |

Now looking a little deeper, the White promotion on light squares must capture PBNR or eBNR (where e means en passant pawn). The latter is not possible, since e, N & R must all be captured on 6th or 8th rank. Similarly for the Black dark square promotion. So the only possibility is:

|  | White dark sq | White light sq | Black light sq | Black dark sq |
| --- | --- | --- | --- | --- |
| King | 1 | 0 | 1 | 0 |
| Promoted pawns | 2 | 1 | 2 | 1 |
| Captured units | 4 | 7 | 4 | 7 |
| Captured e.p. | 1 | 0 | 1 | 0 |
| Total | 8 | 8 | 8 | 8 |

**Case 3** (not possible)

|  | White dark sq | White light sq | Black light sq | Black dark sq |
| --- | --- | --- | --- | --- |
| King | 1 | 0 | 1 | 0 |
| Promoted pawns | 2 | 1 | 1 | 2 |
| Captured units | 5 | 4 | 4 | 6 |
| Captured e.p. | 0 | **3?!?** | 2 | 0 |
| Total | 8 | 8 | 8 | 8 |

This "asymmetric pattern" (and its mirror image) are not possible, because it requires too many en passant. Each promoting pawn can capture e.p. at most once.

---
Tags: chess-variants, pawn-promotion, retrograde-analysis, monochromatic
---


# Question
Title: What would cause FIDE to refuse to rate a tournament which had been correctly registered for rating?
According to this statement from FIDE today:

> Today, on December 18, the mini-matches featuring GM Alireza Firouzja (Elo 2750) began in Chartres, France - his hometown. This seven-game tournament pits Firouzja against three veteran players with an average rating of 2497 Elo points. Concerns have arisen regarding the tournament's potential purpose: whether it was orchestrated to aid Mr Firouzja in boosting his rating for potential qualification into the Candidates Tournament 2024.
>
> The International Chess Federation would like to point out that, according to Clause 0.4 of its Rating Regulations, "FIDE reserves the right not to rate a specific tournament".
>
> FIDE has already sent an official request to the organizers of the event. We will carefully follow and investigate all aspects of the organization of the above-mentioned tournament and all the games played by its participants before deciding whether to rate it.
>
> The International Chess Federation is dedicated to addressing not just this specific case but also similar occurrences that may arise. Discussions will be held to explore potential amendments to the FIDE Rating Regulations, aiming to prevent such situations in the future.

It sounds like FIDE are concerned about the mini tournament but unless there is evidence of players throwing or arranging results I don't see how FIDE can legitimately refuse to rate it. If I recall correctly the Chinese federation did something similar for Ding Liren to qualify for the last candidates tournament.

**Once a tournament has been registered correctly, played and the results sent to FIDE within the required timescale what do the rules say about reasons they can refuse to rate the games played?**

**Afterword:** Nepomniachtchi reacted to Fedorchuk accepting a draw in a winning position against Firouzja with this tweet.

Translation:

> This recalls a tale from Soviet times, when player X agreed to help player Y make a norm. He needed a win, at worse a draw, but the game didn't go well for Y, and at some point he stretched out his hand and said, "I resign!" "I don't accept the resignation!" X replied.

# Answer
I think the relevant detail to keep in mind when comparing the situation with Ding and the one with Alireza is that Ding already had the rating he needed: if I remember correctly, he was the clear world #2 and just needed to get enough games on the books without *losing* rating. Firoujza, on the other hand, has been having quite a poor year and, after his relatively disastrous performance at Sinquefield, is not in the lead for the rating spot: he is now behind Wesley So. So while Ding needed to play just to get a certain number of games in, Firoujza is playing to gain rating, which is where the rating manipulation accusations come in. Another detail to bear in mind is that Ding played (if I remember correctly) all solidly 2500+ grandmasters, including super-grandmaster Wei Yi. Additionally, the majority of the players he played were quite young (all the players he played in the Hangzhou tournament are in their early twenties,) whereas Firoujza is playing a tournament against players all 40+, two of whom are under 2500. So while Ding also played several tournaments against weaker players to qualify for the candidates (though it would have been difficult to play a stronger player unless he challenged Magnus,) Firoujza is playing significantly lower-rated, older players with the hopes of gaining rating off of them.
> 3 votes

# Answer
The reason why this situation is not covered by existing rules is simply because it has not occurred before. New rules are needed, for the sake of future clarity, but not for the sake of deciding the status of these fake-ELO contests. FIDE has already given itself the right to ignore them without saying why. To influence the World Championship by introducing for comparison players so far from that status is grotesque.

It is told that when the poet Byron wished to keep a dog in his college rooms and was told that this was forbidden, he brought in a bear instead because bears were not mentioned in the college rules. I find the analogy irresistable.
> 2 votes

# Answer
FIDE could try to find reasons in their Code of Ethics, perhaps in the fair play section.
> 0 votes

# Answer
It seems that what FIDE can do in such circumstances is retroactively change the rules.

Perhaps some very recent history might shed additional light on what FIDE have announced today, Christmas Day 2023.

On December 20 the US Chess Federation sent a letter to FIDE president, Arkady Dvorkovich complaining about the match and made the following request:

> We urge FIDE to not rate the French event and take steps to require that all FIDE events be registered at least 30 days in advance of their start date. This will reduce the amount of gamesmanship that thwarts the spirit of fair competition during the biannual qualification cycle.

Today FIDE published this document, FIDE Council approves changes in tournament registration procedure. Here is the important part:

> The FIDE Council reviewed the tournament registration procedure and approved some changes, effective immediately (see **FIDE RATING REGULATIONS**). These changes primarily concern the tournaments, with at least one of the participants having a rating of 2700+.
>
> 0.2 The tournaments to be rated shall be pre-registered by the federation in whose territory it is held, and they will be responsible for the submission of results and rating fees. Council may additionally designate these rights and responsibilities to Affiliated Organisations that are representing an autonomous territory which is contained within no more than one Federation.
>
> The tournament and its playing schedule must be registered:
>
> 0.2.1 **Not later than 30 days before the tournament starts, if one of the players in the tournament is rated in excess of 2700, or a female player rated in excess of 2500**.
>
> 0.2.2 Otherwise, three days before the tournament starts.

Sure enough, if you follow the link in their announcement you come to the FIDE Rating Regulations effective from 1 January 2022 and the above is an extract from that document.

Checking the FIDE list of French tournaments registered for December 2023, sure enough, the Chartres event is missing.
> 0 votes

---
Tags: rules, fide, rating, candidates
---


# Question
Title: Why are capturing key moves "frowned upon"?
Wikipedia's article on Babson tasks says:

> However, Yarosh's problem has a small flaw: the key is a capture, something which is generally frowned upon in problems.

(The "key" of a chess problem is the first move in the solution.)

Why is it frowned upon for the key move to be a capture?

# Answer
> 19 votes
I think that the feeling with regard to starting with a capture could expressed by saying that such a move is vulgar, This may or may not worry you

ADDED IN RESPONSE TO OP

Well, it depends on what you think is the pupose of a problem. For some, rather dedicated people, it is an art form, and the composition must follow strict rules, rather like a sonnet. There is strictly no point to asking WHY a sonnet has to follow those rules, but if you don't follow them it isn't a sonnet. And enough people think that the rules are good, that the sonnet form persists. And perhaps you can understand how a purist might regard a "sonnet" that did not obey the rules as vulgar.

But in the case of a chess problem there are reasons for the rules. When playing the game it is useful to look first at forcing moves, checks and captures. Problemists like to make the key move as subtle (and hard to find) as possible and so avoid the sort of moves that a player would be attracted by. Solvers find satisfaction is overcoming that difficulty. In the case of the Babson task, matching underpomotions in attack and defence is so phenomenally difficult to achieve that starting with a capture is regarded as forgivable.

Surprising key moves were a feature of the early problemist Sam Loyd. If you Google his name you may find some entertainment.

On the other hand, if you think of chess problems just as amusing puzzles rather than a minor art form, there is no real reason to accept the artistic conventions.

# Answer
> 10 votes
One reason is that a capture limits Black counterplay. So, if White had captures as options, the solver might well consider them first.

Another is more aesthetic, that a capture increases White's material advantage, and thus makes it less surprising that White managed to checkmate Black. It's considered a good thing if White manages to checkmate from a position where this might at first seem unlikely.

# Answer
> 6 votes
As an minor addition to the already accepted answer, it may be said that since the late 1860s or so 'it has always been that way'. The oldest 'rulebook' for chess problem composition that I know of is from 1878, and its second rule is:

> 2. Capture of a man on the first move of white is not regarded as good unless intricate, beautiful, and numerous variations result from it.

(See http://www.anders.thulin.name/posts/the-art-of-problem-composition/ for the full text: the rules are at the end. It is quite dated.)

Earlier, in the 1850s, many 'good' problems were of the capture-early-and-often type, and were probably designed to show off a solver as someone who could find a forced mate in 18 moves or so. As taste changed towards more modern style (starting in the 1860s), this became old-fashioned and crude.

# Answer
> 1 votes
If you capture a piece as first move, that piece loses its significance. It could have been any piece, or at least one of several. Perhaps even a vacant square would have done. All other pieces are exactly the type they need to be for the puzzle to work.

This makes 1.XxY not exactly a cook, but akin.

---
Tags: problems, terminology
---


# Question
Title: Why is move 12 a blunder for both sides?
I have trouble understanding why move 12 for both sides was such a blunder? Evaluation went roughly from -1 to -6 and back to -1.3. The engine suggests 12... Ne4. I understand that e4 is a good outpost for the black knight. But so is e5 for the white knight and they can go there with a tempo (hitting the queen). That is why I (as black) decided to retreat the knight to d7 to prevent the white knight coming to e5. Analyzing with a computer I see that somehow black is able to make progress after 12... Ne4. But I get lost in the amount of variations and I still don't get it. Is there an easy way to see it?

```
[FEN ""]
                                                                                1. d4 d5 2. Bf4 c5 3. e3 e6 4. Nf3 Nf6 5. Nbd2 c4 6. c3 Nc6 7. b3 b5 8. b4 a5 9. a3 Be7 10. Ne5 Qb6 11. Nxc6 Qxc6 12. Nf3 Nd7 13. Ne5 Nxe5 14. Bxe5 O-O 15. Be2 axb4 16. axb4 Bd7 17. O-O f6 18. Bg3 Be8 19. Rxa8 Qxa8 20. Qa1 Bg6 21. Qb2 Qb7 22. Ra1 Ra8 23. Ra3 Be8 24. Qa2 Bc6 25. Rxa8+ Qxa8 26. Qxa8+ Bxa8 27. f4 Bd6 28. Kf2 Bc6 29. Bh4 Be8 30. g4 h6 31. Bg3 Bg6 32. Bf3 Be4 33. Bxe4 dxe4 34. f5 e5 35. h4 Kf7 36. dxe5 Bxe5 37. Bxe5 fxe5 38. g5 h5 39. Kg3 Ke7 40. Kg2 Kf7 41. Kf2 Ke7 42. Kg3 Kf7 43. Kh3 Ke7 44. Kg2 Kf7 45. Kf2 Ke7 46. Ke2 Kf7 47. Kd2 Ke7 48. Ke2 Kf7 49. Kf1 Ke7 50. Kg2 1/2-1/2

```

# Answer
> 3 votes
Leading up to move 12, black has gained space on the queen's side and can open a file with axb4.

E4 is an important square, and white's Nf3 move gives it up for the short term, granting opportunities for black. As a London player, I would be trying to contest that square and work up to a pawn push to e4 so I can begin to fight back in the center or on the King's side, while undermining black's queen's side pawn chain.

Once both players' knights assume their outputs, the difference between the two is that black's knight attacks c3, a key part of the pawn chain, while white's knight doesn't attack anything substantial. The black queen losing a tempo isn't too important, since it has plenty of squares to go to, and white will need to respond to the threat on c3 after the tempo.

If white defends c3 with the queen, both sides playing axb4 means that black controls the a-file, and white still has work to do to claim e4 and begin any sort of offensive.

If white defends c3 with the rook, they lose the a-file immediately.

# Answer
> 11 votes
The point seems to be that after 12 Nf3? Ne4 Black crashes through on the lightly defended Queenside. For example 13 Qc2 loses directly to axb4 14 cxb4 Bxb4+ because Ra1 is undefended. So 13 Qc1, but Black still has Qa6 followed by opening the a-file, e.g. 14 Rb1 axb4 15 axb4 Qa3: Black soon wins the c-pawn and then the b-pawn, and White will lose the house to the connected passed b/c pawns. (Black can also play it fancy with 13 Qc1 Nxc3 14 Qxc3 axb4, either getting *three* connected passers for the piece with a clear winning path bxa3, b4, b3 etc., or winning the ending after 15 axb4 Bxb4 16 Qxb4 Rxa1+ and 17 . . . Ra4 when White is obliged to offer a Q-trade on d6. Here too it ends with Black getting connected passed b/c pawns that White has no good way to block.)

# Answer
> 0 votes
Moving a piece twice in even a somewhat "slow" opening as the London can be counterproductive. Here the idea behind Nf3 is probably to waste more time with the aggressive-looking Ne5 which would achieve little (and, as Dr. Elkies points out, runs into 12...Ne4). That said, White's position seems difficult regardless but perhaps a more effective plan would be to either castle quickly or try to create kingside/central play with h3, g4, Bg2, etc.

---
Tags: blunder, london-system
---


# Question
Title: Its possible to use PGN EXTRACT to generate split variants and random?
I'm using pgn-extract to generate a lot of positions from my theory. I would like to know if it's possible to randomize the result for losing patterns of this.

# Answer
pgn-extract can split a game with variants into separate games, but it does not have any randomisation features, unfortunately.
> 1 votes

---
Tags: pgn-extract
---


title: Seeking a particular problem

text:
# Question
Title: Seeking a particular problem
I recall seeing a problem in *Games* magazine, probably in the early 1990s, that required the solver to deduce that a capture en passant was possible (not just because that's the only way to get a solution, but using retrograde analysis). I recall that all the pieces (including pawns) on the board were congregated in one corner — if I recall correctly they were all in the first three files and the last four ranks. The solver was required to mate in a small number of moves, possibly two. Does anyone know what problem it is?

# Answer
> 9 votes
I found a problem that perfectly fits your description! I’ve played the position back a move for the double step.

```
[Title "Kurt Keller, Stuttgarter Nachrichten & Südwest Presse (Ulm) 1993, Mate In Three"]
[FEN "5RbN/5ppk/5P1P/5P1K/8/8/8/8 b - - 0 1"]
[startply "1"]
[startflipped ""]

1... g5 {Now White mates in three.} 2. fxg6+! fxg6+ (2... Kxh8 3. gxf7 Kh7 4. fxg8=Q#) 3. Nxg6 Bf7 4. Rh8#

```

If the *Games* magazine flipped the position, then this is a problem with all pieces in one corner, on the first three files and last four ranks, a short number of moves, and an en passant key! Even if it wasn’t flipped, your mind might have altered your memory. Since the problem itself is from the early 1990s, it’s safe to assume that the *Games* magazine reprinted it for show.

**Addendum 7/2/2022:** I came across a mate in two by Pal Benko that also fits the fill perfectly. (Once again, I've played it a move back so the replayer works properly.)

```
[Title "Pal Benko, 1996?, Mate In Two"]
[FEN "kbN5/npp5/B1N5/P1K5/8/8/8/8 b - - 0 1"]
[startply "1"]
[startflipped ""]

1... b5 {Now White mates in two.} 2. axb6! cxb6+ 3. Nxb6# (2... Nxc6 3. b7#)

```

While the YACPDB database actually lists the source as "Games", the Die Schwalbe Chess Problem Datase sheds series doubt that on that publication date/source.

To quote it, translated from German:" In 'My Life' \[,by Paul Benko,\] the original source is "Games 1996" - it is unclear which publication is meant. The name Benko does not appear in the index files of the 'Games and Puzzle Journal' \[Jelliss\], according to 'Chess Periodicals' \[Felice\] there were some magazines that could fit the name (see p.90ff, entries 1016ff), but their publication period ends well before 1990."

The Games and Puzzles Journal archive is here: http://www.mayhematics.com/p/p.htm I found it not in any 1996 issue. Either it is in another issue, with a wrong date given, Benko forget the source to his own problem, another unknown source named "Games" is meant, or one of many strange possibilities is the answer to this problem's origins.

# Answer
> 3 votes
If it's from a source like *Games* Magazine, which does not have a regular chess column, then I guess the problem was not a first publication but a reprint of this Amelung classic, which fits the description almost perfectly up to reflection (and perhaps the reprint *was* reflected):

```
[Title "Friedrich Amelung, Düna-Zeitung 1897, Mate In Two (after ...g5)"]
[FEN "7R/6pp/5P1k/4PK1P/8/8/8/8 b - - 0 1"]
[startply "1"]
[startflipped ""]

1... g5 2. hxg6! Kh5 3. Rxh7#

```

There is no other possible Black move to reach the position after g5: squares f6 and h6 are blocked, so the pawn didn't reach g5 by capturing; bPh7 is on its starting square; Kg6-h6 would have WK and BK attacking each other; and Kg7-h6 would require White's previous move to be with the checking f6-pawn, which is impossible because e5,f5,g5 are all blocked (the first of these is the only reason the e5-pawn is needed in the diagram).

As it happens, in this Amelung problem (unlike the more recent Keller and Benkő problems suggested by **Rewan Demontay**) Black's g5 is not a blunder: any other move would also allow the same Rxh7 mate in the next move or two.

---
Tags: problems, en-passant, retrograde-analysis
---


# Question
Title: When has the FIDE rule against bringing the game into disrepute been invoked (if ever)?
In the current FIDE Laws of Chess article 11.1 says:

> 11.1 The players shall take no action that will bring the game of chess into disrepute.

I have heard elderly arbiters fulminating about some incident saying that this law (which has been around for a long time) should be invoked or that they would invoke it but I have never come across a case in the real world where this has happened. The talk of invoking it has been just "bar talk" as far as I can tell.

I understand the need for a chess rules equivalent of the nuclear deterrent, but has this ever been invoked?

# Answer
> 10 votes
Has the FIDE rule against bringing the game into disrepute been ever invoked? Indeed. I have found several examples of applications of the rule, based on the analysis of many resolutions by FIDE, and a few national and regional chess federations.

**N.B. Although I tried to find references in English, it was hard to do and most of the references I found are in French, Catalan and Italian. The references I could find depend on my knowledge of languages and on the publication of disciplinary resolutions by a particular federation.** (For example, I could not find such type of documents neither at the USCF site nor at the English Chess Federation's).

## Cases of application

I actually found a case similar to that presented by @Brian Towers **for committing illegal moves/actions during a game of chess**. During a rapid chess competition, the white player repeatedly made illegal actions during the last two moves of the game (captured a pawn but did not take it off the board during his own time; retired the pawn during the opponent's time and, because of this movement, displaced a bishop from d4 to f3 and interfered with the opponent; knocked down two pawns while making his next move and did not set them up during his own time). This went unnoticed by the arbiter but there was video footage. The black player made a claim, but lost by time because of this. The result of the game was overturned based on article 11.1 and 11.5 (not annoying the opponent) (decision 3/2016, in Catalan, by the competition judge of the Chess Federation of the Balearic Islands).

However, this type of application of the article seems to be rare and it is more often invoked to punish **inappropriate behavior during a match**. Here are some examples:

* A player broke havoc in disguise during the final of 86th French Championship as part of a prank. According to the arbiter that reported the event, "His behavior and actions have brought discredit to our sport". The player was suspended for two years (Resolution 2011-14 of the Federal Committee of Discipline of the French Chess Federation, in French).
* An adult player shouted to an underage player, accusing him of having touched a piece and not played it. The adult player was suspended for 30 days (Resolution 2020/277 of the National Sports Judge of the Italian Chess Federation, in Italian).
* Two players started quarreling during a match about some pieces having been knocked down. Both players lost the game and were suspended for 30 days (Resolution 2019/259 of the National Sports Judge of the Italian Chess Federation, in Italian).
* A player insisted on using swear words and acting disrespectfully, even after several requests by the arbiter. The player was suspended for two months (Resolution 2017/155 of the National Sports Judge of the Italian Chess Federation, in Italian).
* While playing against an underage player, an adult player repeatedly went to the bar for alcoholic drinks (although he apparently was not inebriated). He was reprimanded on the grounds of article 11.1 (Resolution 20/2019 of the Catalan Chess Federation, in Catalan).
* A player was reprimanded on the grounds or article 11.1 for shouting during a match when his opponent's phone alarm rang (Resolution 7/2019, of the Catalan Chess Federation, in Catalan). (The other player was reprimanded for telling the delegate, but not his opponent of the fact that the alarm would ring to remember him to take his medication. The competition rules specified he should have told both about it.)
* Several players were reprimanded for misbehaving (shouting, speaking aggressively) because of a conflict during a match (Resolution 07/2017 of the Catalan Chess Federation, in Catalan).
* A team's delegate was reprimanded for acting angrily when making a claim (Resolution 06/2017 of the Catalan Chess Federation, in Catalan).
* A player was reprimanded for refusing to shake hands as customary at the beginning of the game (Resolution 17/2016 of the Catalan Chess Federation, in Catalan).
* An adult player has suspended for six months for acting pejoratively against two underage opponents. The decision was confirmed during an appeal based on grounds of article 11.1 and 11.5 (Appeal Resolution 15/2016, of the Catalan Chess Federation, in Catalan).

Article 11.1 has also been used to punish **affronts and offenses against chess organizations**:

* The president of a chess club was suspended for three years for offenses against the French Chess Federation on Twitter and for manhandling a couple of underage players he trained (Resolution 2019-14 of the Federal Commission of Discipline of the French Chess Federation, in French). Although the resolution does not cite explicitly the article 11.1, it says that such actions (the insults on Twitter) "are of such a nature to attack the image of the French Chess Federation and the game of chess" (my translation).

## Penalties

As is apparent from the examples above, in case of minor transgressions penalties are limited to admonitions with more severe punishments in case of re-incident behavior. In more severe cases it results in the loss of the game or even license suspensions.

## Alternatives to article 11.1

The invocation of article 11.1 seems to depend on the actual regulations of each federation. In fact, the offenses listed above are related to violations of ethical codes in some federations.

For example, the article 2.2.10 of the FIDE Code of Ethics is approximately equivalent to article 11.1 of the Laws of Chess. It states:

> "In addition, disciplinary action in accordance with this Code of Ethics will be taken in cases of occurrences which cause the game of chess, FIDE or its federations to appear in an unjustifiable unfavorable light and in this way damage its reputation."

This article was used to suspend former FIDE president K. Ilyumzhinov (case 2/2018 of the FIDE Ethics Commission) for pursuing his own interests instead of FIDE's in addition to other actions.

Also, in France disrespectful behavior is usually judged as violations of the Ethics and Deontology Chart of the French Chess Federation (e.g., Appeal decision 2017-02 for hitting a player, decision 2019-01 for insulting and menacing two players, decision 2019-13 for shouting to the opponent, in French).

Finally, the ruling 2/2020 of the FIDE Ethics & Disciplinary Commision regarding an attempt of match-fixing states that "Art. 2.2.10 is a more general rule, primarily aimed at targeting acts or omissions by players or office holders that is not covered by any of the more specified articles in the Code of Ethics." I think this should also be applicable to article 11.1 of the Laws of Chess.

# Answer
> 9 votes
The closest I have come to a definitive positive answer is this post in the English Chess Forum by Canadian International Arbiter Pierre Dénommée.

Here is the relevant part of the post -

```
[fen "8/p7/1p2q1k1/4p1P1/2P5/1P1R4/4K3/8 w - - 0 1"]

```

> White did move his rook between d5 and d6 and pressed his clock, he could have tripped his rook after, this would not have changed anything. Black assumed that the rook was on d5 because it would be unprotected on d6. Black did play Kxg5. White then adjusted his rook to d6 and played Rxe6. ***The final result was 0-1 for bringing the game*** ***of chess into disrepute***. No illegal move has occurred, but doing nothing when a player change\[s\] a completely lost position into a won position by an unsportsmanlike conduct is not acceptable

Emphasis added by me.

This was posted as part of a discussion about players knocking over a piece in blitz and pressing the clock without putting the piece back in place and so, unfortunately, no further details of the game or decision were included.

# Answer
> 6 votes
This has now happened in a world championship event, thereby setting a precedent that arbiters at lower levels are likely to follow. The chief arbiter in the 2023 World Blitz championship has decided that top players Dubov and Nepomnichtchi colluded before the game to decide the result.

Here is the game:

```
[Title "Dubov - Nepomnichtchi, World Blitz Championship 2023"]
[fen ""]

1. Nf3 Nf6 2. Nd4 Nd5 3. Nb3 Nb6 4. Nc3 Nc6 5. Ne4 Ne5 6. Ng5 Ng4 7. Nf3 Nf6 8. Ng1 Ng8 9. Nc5 Nc4 10. Na4 Na5 11. Nc3 Nc6 12. Nb1 Nb8 1/2-1/2

```

Here is the decision:

FIDE's announcement of the decision on Twitter/X.

---
Tags: rules, history, fide
---


# Question
Title: Is 9... Be6 a good move in this position?
```
[FEN ""]
[Startply "19"]

1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 d6 8. c3 O-O 9. h3

```

In this position, most top players will continue with 9...Na5, 9...Nb8 or 9...Bb7, and extremely rarely (about 1 percent of the time) do we see the move 9... Be6. However, an engine seems to suggest 9... Be6 in this position. Should I trust the engine's judgment on this move? Or should I trust the traditional opening theory?

# Answer
> 2 votes
The first thing to note is that 9...Na5 and 9...Be6 can transpose if white replies to each with 10. Bc2. Before playing 9...Be6 you should decide how happy/comfortable you would be if white chooses to exchange with 10. BxB. If you prefer to keep pieces on the board or dislike the change in pawn structure then choose one of the other moves, maybe go with 9...Na5.

The moves 9...Na5, 9...Nb8 , 9...Bb7 and 9...Be6 are all played with different ideas in mind. Although they are all evaluated similarly by engines they can lead to very different positions. Which one you choose should be decided by how comfortable you feel in the types of position which result, how familiar you are with those positions and to a lesser extent how familiar/comfortable you believe your opponent is.

> Is 9... Be6 a good move in this position?

It is perfectly sound. The decision which move to make in this position is one of style/familiarity and preference.

---
Tags: opening, engines, ruy-lopez
---


# Question
Title: Which federation would a cruise ship FIDE rated tournament be rated under?
I know bridge tournaments are a big thing on cruise ships. I think I've seen adverts for a chess tournament on a cruise ship several years ago but can't remember the details or find anything online. Chess tournaments on cruise ships don't seem to be a thing, maybe because of problems registering them for FIDE rating.

Suppose you were a cruise ship company wanting to stage FIDE rated tournaments. Given that they would take place in international waters outside the jurisdiction of any national federation how would you register your tournament for FIDE rating?

Normally if you want to register a tournament for FIDE rating you give the details to the hosting federation's IRO (international rating officer) usually via an automated online form and they register with FIDE.

I know there is a special federation, FID, for players who can't be registered with their national federation. Currently a lot of Russian players are registered as FID. In the past Iranian players who have been persecuted by their federation have moved to FID. But I don't think FID has an IRO through which you can register tournaments for rating.

# Answer
> 3 votes
Because this is "legalese" it can be somewhat tricky to pin down an answer because with all things legal the magical phrase "It depends" will arise a lot.

Generally speaking though. Maritime law is only focused on safety and operation standards whilst at sea, outside of a countries maritime economic zone. This doesn't mean, free for all no laws on the high seas.

Usually boats will operate under similar laws to where the boat is registered. Again , this raises an interesting issue , because a large portion of boats are registered under what is called "A flag of convenience".

> Example: Swedish shipping company registering their ships in Panama for tax purposes.

Over time the drift from the "laws" observed on a boat have shifted from their registered nation, to the nation of which the parent company is primarily operated from.

All the above is kind of a moot point however. FIDE is a governing body over a sport with ultimately no legislative power. They can recognise a Chess Tournament operated outside of any country jurisdiction if they so choose. More importantly , generally speaking any "legal" writs that may arise would be civil in nature and operating outside of any jurisdiction would not be a recognised defence. This is seen repeatedly where Party A from Country A sues Party B from Country B , and the court hearing could occur in Country A,B or anywhere else (sort of).

An interesting article link regarding legal implications for sports and jurisdictions. This specific edge case isn't covered.

**EDIT:**

Following writing this,

I have found the following: https://www.schachturnier-auf-see.de/english/the-tournament

This is a ship operated by Norwegian Cruise Line Holdings, which is registered in the Bahams (flag of convenience), travelling between Puerto Rico and Portugal where they are holding a FIDE recognised chess tournament being overseen by a Private Company who is using the German chess body as the overseeing group.

---
Tags: fide, rating, tournament
---


title: Outside-the-box mate-in-one challenge

text:
# Question
Title: Outside-the-box mate-in-one challenge
> I've received an (I would say impossible) `mate-in-one challenge` and I have already checked all movements, but couldn't solve it yet. It came from a trustable source and they say *you need to think outside the box*, so certainly there's a solution. Can someone help me to find it out?

```
 [FEN "2q1rb2/pR3pkr/3p2pN/2nPp1QP/1nB1P1b1/6N1/PBP3P1/5RK1 w - - 0 1"]

1. Qg6 Kh8 (1. Qf6 Kh6) (1. Qe5 Re5) (1. Be5 Re5) (1. Ngf5 Kh8) (1. Rff7 Kh8) 2. Qg8

```

White moves, and it is pretty close to win. `Qxg6, Qg8` could be a two-movement winning sequence. However, as said in the challenge statement, **it is possible to be victorious in the very next movement**, so I have been wondering how!

## The original statement is:

> Today's puzzle is one of the most trickiest chess problems you'll ever see. All you need is to think outside the box. White to move and mate in one! Yes, in one move. No, no extra pieces are appearing on the board likewise no removal. It's achieved with one unique valid movement, are you able to solve it?

There's just 6 possible checks white can do (I mean, i just saw 6). All them are included in above board followed by how black escape from it.

Can anyone find the solution?

Also also also also, for honesty here, I googled the FEN to find the answer.

# Answer
> 18 votes
I checked with Stockfish and indeed there is no normal mate in one for White, and there isn't a mate in one for Black either. So this obviously a trick/joke problem.

The trick is this: What last move of Black would allow a mate in one?

Solution:

> The mate in one is “1. dxe6#” en passant! This move takes away the Black king's only flight square on h8, which is what stops any other attempts by White.

Explanation:

> The joke is that it can't be proved that Black's last move was “0... e5”. The accepted convention in chess problems is that an en passant capture is only allowed on the first move of the solution if it can be proved that the captured Black pawn made the double-step as Black's last move. It is obvious that Black has plenty of possible last moves other then e5, hence why this a trick problem.

# Answer
> 4 votes
> It's an "en passant" problem.
> Black's last move had to have been `0..., e5`. Then when white captures the pawn en passant with `1. dxe6 e.p.`, black is mated by the white bishop on b2 since the black f7 pawn is pinned by the white b7 rook and can't interpose to block the bishop.

# Answer
> 2 votes
Black touched the white queen rook but moved their own rook from d8. Therefore, they have to undo the rook move, putting that rook back on d8. And capture the white rook with the Queen. Then B x P is mate. Because the board is upside down. Well, okay, if the board is upside down, it wasn't White's Queen rook, but the King Rook. NO matter.

# Answer
> 0 votes
Black's last move was 1.....e7-e5, & so the mate in one is achieved with 2.de6 en passant (ep). Stockfish will have to do better. I have featured this study on my YouTube channel, plus a lot more. Happy solving! NB. I note in the 'spoiler' that it is of the opinion that Black had many alternatives to 1....e7-e5. Not so, because White's last move was evidently 1.Bb2+ (B at c1 to b2, as per my video on YouTube from 11 months back), requiring either the given reply or 1...f6 (2.Bf6# to finish). This proves my answer is not repeating others, but, on the contrary, identifying the correct sequence & that no 'trick' or 'spoil' exists. To sum up & leave no room for doubt (thus vindicating the composer),if the Black e-pawn were on e6 then 1...f6 would not be possible (f-pawn pinned by the Rook at b7, hence no alternative move at all), & that e6-e5 would not enable White to deliver mate in one & so e7-e5 is the only possible & logical reply to 1.Bb2+ to bring into being a # in 1.

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Tags: analysis, checkmate, problems
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title: free alternatives to SwissSys?

text:
# Question
Title: free alternatives to SwissSys?
I was going to do a tournament recently, and then, I found out just *how much* ***$$*** SwissSys Tournament software costs...

My question is:

> What good alternatives to this expensive mainstream software are there, if any?

# Answer
> 2 votes
The FIDE's software Swiss manager has a free demo version. It contains many options for different types of "tournaments". But you will need a bit of time to learn how to use it. I have already used this program with success.

# Answer
> 3 votes
The one I like is Vega - http://www.vegachess.com/tl/index.php. This is free on Linux. The guy who wrote it is an open source supporter who welcomes feedback and is willing to make changes. He is also an active FIDE arbiter. It is also free on Windows for up to 30 players and 50 euros for unlimited use.

There is a review by an English arbiter here - http://chessarbitersassociation.co.uk/Vega.pdf.

# Answer
> 2 votes
The answer to this question depends at least in part on what rating system you want to use when running an event, as well as what your definition of "good" is. It's worth noting that pairing programs require a lot of time, testing and maintenance. So, if you see "good" as synonymous with "cheap" or "free", there probably isn't anything available that will work.

If you're planning a FIDE rated tournament, you can find a list of the approved pairing programs here: https://www.fide.com/FIDE/handbook/C04Annex3\_FEP18.pdf. Of these, Swiss Manager is, IMO, the best bet, not least in part because it offers one-button Web publishing of results and pairings.

if you're planning a US Chess rated tournament (as opposed to the FIDE rating system), your best options for pairings are as follows:

You won't be able to generate the files required for electronic submission of US Chess rating reports without either SwissSys or WinTD. Either pairing program would work well for you.

There is a reasonable argument that arbiters should learn how to pair by hand before jumping in to using a pairing program.

# Answer
> 2 votes
Our chess club, Media Chess Club, uses Chess Nut for club management and pairing. It is free and user friendly. The automatic Swiss pairing works as well as SwissSys (which is what we were using before Chess Nut). It also comes with a bunch of additional features that SwissSys does not, like member management and public joinable events (with landing pages and public urls). Its relatively new and they are rapidly enhancing it. They are responsive and take our club's feedback which is nice. Definitely check them out in your search

# Answer
> 1 votes
You can try my program VinczeSwiss. Freeware! Now (25.12.2022) in 7 languages! ... Websites: http://vincze.euweb.cz OR https://sachy-hb.cz/vinczeswiss\_eng/

# Answer
> 0 votes
French Chess Federation has developed a nice software named PAPI.

It is free for anybody who has a licence with the French Federation. If you don't, you can ask for a copy via un email to Mr. Erick Mouret (erick.mouret@free.fr).

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Tags: software, tournament, tournament-directors
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# Question
Title: Need help on a specific situation (beginner friendly)
I am a beginner and got myself into this situation. (I'm white) Is there any way to get out of it or some tips somebody can give me or is this situation hopeless? I would appreciate it if you took a tiny bit of your time to help me! (by the way, the pawn on Black rank is an accident it's supposed to be a bishop)

# Answer
> 2 votes
First off, if this is a game in progress against a person, it's generally considered cheating to be asking other people for advice. I'll assume you're against a computer or it's a friendly game and you have permission from your opponent to ask.

So... you're down a rook, a bishop, a knight, and a pawn. I'd call that hopeless if your opponent is any good. The main thing you have going for you is that Black hasn't yet developed their extra pieces, but they can do so very quickly.

1.Qxh5 wins a pawn and threatens 2.Qf7+ forking the king and rook. But if Black plays 1...Nd7 then 2.Qf7 isn't a check. And trying to get fancy with something like 1.Qxh5 Nd7 2.Qd5 doesn't really work because then Black plays 2...Bc5+. This breaks the pin and you'd lose have to give up your rook for the bishop, and Black's rooks are guarding each other. Even if Black doesn't see Qf7 and you win the rook for free, you're *still* down a bishop and knight, which is more than enough for Black to win if they're any good.

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Tags: analysis, strategy
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