The Chess960 analogue in shogi, xiangqi, etc Fischer said

In chess so much depends on opening theory, so the champions before the last century did not know as much as I do and other players do about opening theory. So if you just brought them back from the dead they wouldn’t do well. They’d get bad openings. You cannot compare the playing strength, you can only talk about natural ability. Memorization is enormously powerful. Some kid of fourteen today, or even younger, could get an opening advantage against Capablanca, and especially against the players of the previous century, like Morphy and Steinitz. Maybe they would still be able to outplay the young kid of today. Or maybe not, because nowadays when you get the opening advantage not only do you get the opening advantage, you know how to play, they have so many examples of what to do from this position. It is really deadly, and that is why I don’t like chess any more.

and

[Capablanca] wanted to change the rules already, back in the twenties, because he said chess was getting played out. He was right. Now chess is completely dead. It is all just memorization and prearrangement. It’s a terrible game now. Very uncreative.

and (emphasis mine)

I love chess, and I didn't invent Fischerandom chess to destroy chess. I invented Fischerandom chess to keep chess going. Because I consider the old chess is dying, or really it's dead. A lot of people have come up with other rules of chess-type games, with 10x8 boards, new pieces, and all kinds of things. I'm really not interested in that. I want to keep the old chess flavour. I want to keep the old chess game. But just making a change so the starting positions are mixed, so it's not degenerated down to memorization and prearrangement like it is today.

2 Questions: Does shogi, xiangqi or other co-hyponyms suffer any of the same problems that chess does, according to Fischer, which led him to invent chess960? Are there any analogues of chess960 in shogi, xiangqi or other co-hyponyms?
Notes to explain what I understand and to hopefully further clarify this question:
Note 1: I mean I really don't see any difference. They're abstract strategy mathematical board games that have pieces and stuff and there's always the same starting setup, soooo...
ETA Note 1.1: There seems to be an answer about how xiangqi is indeed like standard chess and yet another an answer about how shogi isn't. Most of what I know about shogi is from Shion no Ou, but I really do not see how standard chess is unique in this or at least how shogi isn't the same this regard. Again, they are all mathematical and abstract strategy games that involve pieces on a board and have the same starting position of the pieces. I believe it's the same with draughts/chequers. In each game, opening theory is I believe not only extremely viable to study but will dominate a very large portion of what a player ought to study.
ETA Note 2: Actually, I think the same problem will befall, for example the chess variants closer to the standard (in terms of the pieces used), such as 4 player chess, bughouse, crazyhouse, torpedo chess (the torpedo pawn thing), '5D Chess with Multiverse Time Travel': The initial setup is always the same, so it seems like, eventually, it's just gonna be about openings. Of course, each of these chess variants can be fixed in this regard by doing chess960 type shuffles or something.

For shogi and xiangqi, the answer is no. There is no analogue for western Chess960 in those chesses. Disclosure: I'm a decently strong player in all three.
The problems Fischer identified in those quotes you gave are that western chess favours the player with more opening preparation, and that there is no room for creativity. (Bear in mind that this is his own view as an insanely strong player who had reached the top level of the game back then.)
To answer the question from a broader context, I will give a little bit of history and cultural context to show why shogi and xiangqi, despite also suffering from the "dogma of opening theory", never arrived at randomisation of the start position as a solution - indeed, the opening theory is not even perceived as a severe problem.
(Also, I will keep the context to professional/master players; at the amateur level, really anything goes for openings in all of the chesses.)
Shogi
Opening preparation is indeed important at the top levels. Historically the game has progressed from slower, cautious buildups favoured in the 17th-19th centuries, towards the more modern, faster game of the mid-20th century to today.
There are very sharp openings where one/both sides start attacking early and both players must walk tightropes (e.g. New Rapid Ishida; yokofudori/Side Pawn Picker; some lines of Gokigen Central Rook).
There are openings that have been examined to great depths (60 ply, even 80 or more ply) and involve many move order subtleties (Double Yagura games; Bishop Exchange; One-turn-loss Bishop Exchange).
There are openings which have gone even further, to survive in the ecosystem around it. (Fujii System was analysed literally all the way to mate in some lines by its inventory, Fujii Takeshii 9-dan.)
But yet, in the middle of all this, there is still room for creativity and variety. By the 1990s, of the two main styles, Static Rook was seen as the superior choice over Ranging Rook. The great player Habu Yoshiharu sparked something of a renaissance by playing Ranging Rook as an upstart young challenger in a title match - and winning. Since then different Ranging Rook styles, and even double Ranging Rook games, have never truly fallen out of favour at the professional level, even when engines overtook humans and universally preferred Static Rook.
There is more than enough to analyse, and still more creativity to be had (especially in double Ranging Rook games) - there was not a need for randomised shogi. This is of course not even mentioning arguments from tradition - there is no way that one can redo national culture by randomising the start position.
(Oh, and yes, randomised shogi would heavily disrupt existing opening theory, at least with regard to concrete moves.)
Xiangqi
Even before I talk history, the simple logistics of it is that xiangqi pieces don't randomise well. The kings, advisors and elephants are bound to the few points they can leap to, and are almost worthless if randomly shuffled away; the cannon movement means that they also don't randomise well, since on the first move already captures may be possible.
Now the history. Again, opening preparation is important at the top level. This should be no surprise again, as top players do like to seek any advantage they can get.
In ancient times (think 800 years ago), xiangqi was thought to be a win for red, the first player - classical manuals do some analysis on opening traps and games for red to win with central cannon versus screen horses, or opposing cannons (either one).
Fast forwarding to more modern times, there was the same sort of status quo from chess and shogi at one point: it was thought that black had trouble neutralising red's initiative, and the only defence against a central cannon was screen horses. The theory debates in this flowed from the 1930s onwards in national tournaments in China, with multiple red and black setups tested in battle.
In the 1960s, Grandmaster Hu Ronghua decided to revisit a "busted" opening. Was the Fan Gong Ma defence for black really losing? With tons of effort into research and with sheer playing strength, GM Hu Ronghua managed to bring the dead opening back to life, winning big tournament games with it and drawing other masters to try it. Again, this brought forth another period of experimentation that has not quite died down; even today, masters are exploring more than ever other red openings than a central cannon, with more fertile ground waiting to be explored.


On a glass board, which is "white"? I have a chess board made of frosted and clear glass pieces. The board is also comprised of alternating clear and frosted glass squares. I'm never sure how to orient the board. Which is the official "light colour" to put in the lower right corner?

At the lower right corner, the square's color should be White.  I have seen some glass chess boards and most of the times the frosted pieces/squares represent the Black side, and the clear pieces/squares the White side.


Are there any other endgame analysis tool than Wilhelm? Are there any other endgame analysis tool than Wilhelm?

Finalgen (http://finalgenchess.ovh/home_ing.php) generates database for positions with kings, one piece each, and any number of pawns. It has it's disadvantages, but it's free.


Which sites offer good tutorials for novices to improve? Can anyone recommend sites that they have personally had experience with to be good for learning by novices? I play chess regularly, but I have never studied theory and while I am doing fairly well against most of the regulars I play against, there are several people who are able to have a clear advantage by the midgame.

I'd like to improve my openings by studying theory, but I've never looked at it before, so I wouldn't be helped much by a dry treatise on how to develop a pawn line against, for example, 1.d4. I'm looking for an objective analysis of websites that teach the theoretical principles of openings, with good examples and a minimum of references to various famous openings.

IMHO if you are struggling with the middle-game it makes more sense to study that particularly (as well as the endgame) instead of focusing on openings. I would advise you to learn to record your games in Algebraic Notation in order to learn from your mistakes (preferably with a stronger player). As far as online material you can use I can recommend Novice Nook by Dan Heisman and Modern Ideas in Chess by Richard Rèti


How do I determine who has white or black? I have used e.g. the game of paper, stone and scissors. Is there another method which determines who has white or black? If so, what is the method?

White always moves first. To determine who plays white in a friendly game, you can:

Toss a coin
Roll a dice
Play an even number of games, alternating sides
Play rock-paper-scissors
One player takes a white pawn and black pawn, and secretly places one in each hand. The other player picks the hand and therefore the colour to play
Use any other agreed method

In tournament play, who plays which colour is determined by the organisers and you should be informed of which colour to play before each game. If you are unsure, ask an arbiter or an organiser for clarification.

Please note that the initiative is a specific chess term defined below:

  Initiative in a chess position belongs to the player who can make threats that cannot be ignored.

Source: Wikipedia


What is the most efficient way to calculate attack squares in a chess engine? I have made a chess engine, and it seems from cProfile that my most expensive function is the one that calculates attack squares for both players. Here is the cProfile results for a perft function I wrote that goes 4 ply deep: https://imgur.com/a/VMoF3G5

The reason why my calculate attack squares function is so expensive is because every time a move is made in perft, the position is a new one, and attack squares for both players have to be recalculated. My question is this: Is there a more efficient way to be calculating attack squares for both players? Is there a way I can avoid having to recalculate attack squares for all 32 pieces every time a move is made in perft? Thank you.

https://repl.it/@kasparov/ImportantNotedCoderesource
My code for anyone who's curious

It may help to keep a list of each piece and the squares it attacks for the position.

Then when a move occurs, you can reduce the work calculating for the pieces that don't move. Non-moving kings, knights, and pawns will attack the same squares as before. Non-moving queens, bishops, and rooks only need to be recalculated if a piece moved to or away from a square they attacked.

Then you can update the attack squares of the pieces that actually moved.


Sicilian Lowenthal-Labourdonnais I am very interested in the Lowenthal Sicilian, specifically the 5. Nb5 a6 line:

e4 c5
Nf3 Nc6
d4 cxd4
Nxd4 e5 (signalling the Lowenthal)
Nb5 a6 (5 ... d6 is the Kalashnikov variation or what Silman refers to as the Neo-Sveshnikov)
Nd6+ Bxd6
Qxd6

[FEN ""]
1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 e5 5. Nb5 a6 6. Nd6+ Bxd6 7. Qxd6

So variations begin here with ...Qe7 or ...Qf6

Now here is where my problem starts, I can not find a book on this line of the Sicilian for the life of me. It's a fairly popular line among GM's and strong players at my club. I really want to become well versed in it. I have studied a dozen or so GM games from the Lowenthal PGN file I downloaded from chess mentor but I learn much quicker from books where they explain white and black's long-term goals and strategies.

Can anybody recommend resources that will allow me to study this line?

Any book covering the Open Sicilian from White's point of view should have a line against it. From memory White has a queen exchange, Qc7 or Qd1 in one of those variations.

EDIT: For starters try Dismantling the Sicilian by De La Villa. As stated above I recommend any complete repertoire book for White with the open Sicilian.


Is there a chess.com Python api? I want to program a bot and implement it on chess.com, but are there any types of chess.com Python api which will make the bot use the chess.com interface?

Yes there is a Python wrapper to the Chess.com API. Here's the package: https://pypi.org/project/chess.com/


Psychology of moving a piece I've noticed that many amateur games degrade incredibly once they enter mid-game (meaning move beyond opening theory).

There are some great questions and suggestions about improving mid-games, such as strategies to improve positions etc.

Yet, many players with mediocre ratings (myself included) cannot help but make impulsive moves, blunders, simply because they have not approached the move carefully enough.

So my question is this: Does anyone have suggestions for improving mental discipline when making moves?  I'm thinking of suggestions such as; examine how your move might weaken positional defence; or, have you observed how many pieces are attacking the square your moving too?

There has to be some methodological way of improving one's game by improving one's mental discipline.

Yes good habit building is necessary. You need a chess-checklist in your mind. Prepare your checklist before a game, and then go into the game while using it. As you become a higher-rated player your checklist will evolve.

Look for all the "check" moves you can make in a position at each turn.
Look for all the "threat" moves you can make in a position. (this may include simple tactics)
Look for all the "tempo" moves you can make in a position. (as in, attacking a piece that forces the opponent to move).
Look for all the complicated tactical moves, combinations of moves.

As you evolve the checklist becomes smarter:

Look for all "double threat" moves.
Look for all "tempo" moves but also "counter-tempo" moves (where the enemy moving the piece is actually helping your enemy's position become better).
Look for all the counter-checks
Look for all undefended pieces
Look for all weak points in enemy structure

These checklists become more elaborate in the mid-game and you play slow-games to build up that habit, until it is subconscious. Then you can play faster games.


Precise skills connected with rating value I recall a quote that went something like that: "A 1800 beats a 1500 by tactics, a 2100 a 1800 by foo, a 2400 a 2100 by bar and a 2700 a 2400 by opening(?!)". "Endgame" was in it too, I think. Anyway. Maybe one of you remembers the source and exact formulation. But is there actual truth to it, and you may correlate specific skills with ratings? Clearly, this must be seen in average - I was already an endgame titan with 10 year or so, but reached peak 2300 only decades later - individual player skill strengths exist. (Question obviously inspired by this one)

What I certainly agree with is that 2700+ vs 2600 is mostly openings, and everything under ~2000 is decided by blundering pieces e.g. simple tactics. Which, in turn, means that if one wants to reach 2000, the first task is to stop giving pieces away.


Chess challenge #3: Pinned knights Here it is a new chess problem much more difficult than the previous one. The diagram position is the following:

[fen "3rr2k/6pp/p2q1p2/5P2/3Nb3/1P1RQ1NP/6P1/7K w - - 0 1"]

Black has just played Bxe4 but that is not a good choice. How should White continue in this position?

I took this problem from the Chess Tactics Server. I hope this takes more time to be solved than the previous one.

EDIT:

  After Nxe4 Black plays Qd4 instead of Qe4, giving White the choice of playing a powerful movement.

Attempting to answer the revised puzzle:

   1.Nxe4 Qd5 2.Qg3 with the threat of 3 Ne6 winning due to double threat (4 Qxg7 and discovered attack from the Rd3).  White still carries out this threat if Black answers 2.Qg3 with either Qxe4 or Rxe4.  Presumably this is strong enough that the engines didn't even let Black answer 1.Nxe4 with Qd5.  Note that this tactic also depends on Qg3's access to d3 (after Qxe4 3 Ne6 Qxe6 4 fxe6 Rxd3) and the 8th rank (for Qxe4 3 Ne6 Rxe6 4 Rxd8+ Re8 5 Qb8!).


How are PGN ambiguities handled? How are ambiguities handled when writing the PGN when more than one piece of the same type can move into the same square?

[FEN "1R4QQ/R1R4Q/8/6pP/5P1P/8/NK1k4/1N1N4 w - g6 0 1"]

Note: It isWhite to move, with an en passant capturing square on g6.

What would happen if:

the top rook moves to b7?
one of the bottom rooks moves to b7?
the left pawn takes xg5?
the bottom right pawn takes xg5?
the top right pawn takes xg6 by en passant_?
the top left knight goes to c3?
one of the bottom knight goes to c3?

Edit (bonus question):

What would happen if any queen wants to go to g7?

From the specification:

A basic SAN [Standard Algebraic Notation] move is given by listing the moving piece letter (omitted for pawns) followed by the destination square. Capture moves are denoted by the lower case letter "x" immediately prior to the destination square; pawn captures the file letter of the originating square of the capturing pawn immediately prior to the "x" character.

And

In the case of ambiguities (multiple pieces of the same type moving to the same square), the first appropriate disambiguating step of the three following steps is taken:
First, if the moving pieces can be distinguished by their originating files, the originating file letter of the moving piece is inserted immediately after the moving piece letter.
Second (when the first step fails), if the moving pieces can be distinguished by their originating ranks, the originating rank digit of the moving piece is inserted immediately after the moving piece letter.
Third (when both the first and the second steps fail), the two character square coordinate of the originating square of the moving piece is inserted immediately after the moving piece letter.

1: Rbb7
2: Rab7 or Rcb7
3: fxg5
4: hxg5
5: hxg6
6: Nac3
7: Nbc3 or Ndc3
Note that this is simply how the specification is written. En passant captures should not be an edge case, but they are unlikely to be implemented correctly 100% of the time. You'll have to test your replayer to see whether it handles these cases correctly or not.


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

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

If you're looking for the puzzle with the longest forced sequence, it would be this position ,which contains a win for white in 549 moves.
[FEN "1n1k4/6Q1/5KP1/8/7b/1r6/8/8 w - - 0 1"]

It was found by computers from the generation of 7-man endgame tablebases, and there are several similar positions with the same distance to mate.
If that seems a little extreme, then the longest mate puzzle made by a human was Otto Blathy's 'monster', which is a mate in 292 moves but contains an illegal starting position (i.e. it could never occur in a real game).
If you won't accept that, then here are the current record-holders for the longest puzzles created by a person from legal positions - A mate in 271 with 'obtrusive units' (legal, but must have come about through piece promotion, such as having two dark-squared bishops) and a mate in 267 without those. And, surprisingly, both of those were created by the same person.
As for the "most variations that don't work" as you stated, it's probably also the mate in 549 listed above, with the number of moves that would let the other player slip out or otherwise prolong the sequence even more.


Resources on Italian Game, Two Knights Defense with 4. d3 h6 and quick ...g5 Do any books or other resources discuss this variation for Black? Does it have a name?
The general idea is to go 4...h6, then ...d6 and ...g5 in some order, depending on what White does.
S. Mamedyarov plays this line a lot.
Sample line:
 [FEN ""]
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d3 h6 5. c3 d6 6. O-O g5

FM Andrey Terekhov's Two Knights Defense repertoire on Chessable uses this variation against 4.d3.
That repertoire deserves to be more widely known: it's one of the best on Chessable, the author updates it frequently, and it's free!
In the introductory text of 4.d3 h6 he notes:

In the beginning, this line has been mostly used as a surprise weapon, but in the past two years it developed its own body of theory. GM Alexey Kuzmin published a couple of articles summarizing the latest developments in this line in "ChessBase Magazine" (in 2018) and in Russian "64" (2019) .

So those are sources too.
And according to a ChessPub discussion, there are also two analyzed games in this line in Alexander Ipatov: Unconventional Approaches to Modern Chess Volume 1; Thinkers Publishing 2019, although I don't see it in that book's list of contents.


Learning to visualize the board I have read in several sources, it's a important to be able instantly say what colour a square has or for example, if two pieces are on the same diagonal/rank/file, if their squares are given. And this skill can be learned by specific exercise for visualisation.

Is this true?

Is it important to learn this skill isolated from other chess improvement learning?

This is not specifically for diagonals, but this is how I learned to visualize the board. I am not sure that I agree that you should be able to know what color a particular square is. I have been playing tournaments for 40 years this year, more than 30 at the master level, and I still do not think about the color of squares at all with regards to calculation (sure when it comes to making my bishop bad, and other positional elements). I just know where my pieces are, and with experience, where they can go. If I can visualize the former, then the latter is easy.

This is related to tactics, but specifically meant to be different. You can use a different book, but I started with Chernev's "Combinations, the Heart of Chess". The reason I used this book is that many of the examples are longer than normal, but not full game length, and they are interesting and fun. Some get to be 20 moves, or more.

Except maybe on short ones, you are not trying at all to solve them. ALL you are trying to do is keep the position in your head accurately, including sub-variations that are given. When you have visualized it well enough that you think you have it right, put it on a board, and see how well you really did visualize the position, especially, the final position. As you get better at this, you can use full-length games. Again, unlike tactics training, you are just trying to visualize where the pieces are.

Another fun book to do this with is Chernev's "1000 Best Short Games of Chess" since it starts with 4 moves and gradually goes up to 25 max. The only problem is both books I mentioned used descriptive notation, and if that is a problem, you will need to find other interesting shortish games to do this with.

Again, I suggest trying to visualize the whole board. If you do that, you will also see diagonals more clearly.


An online dictionary of fairy chess pieces indexed by move While trying to accurately describe the intended movement of the "doubled knight" in this chess puzzle, I realized that what I really wanted right at that instant was a "dictionary" that would let me look up the established name for a fairy chess piece based on its movement (or lack thereof).
Ideally, I'd like to be able to load up a graphical board like in lichess's editor, drag-and-drop pieces (including a placeholder for "my mystery fairy piece") to create a position, and then mark subsets of the squares as "attacked" or "not attacked," something like this:

and then the tool would tell me, "Ah, the piece you're referring to is commonly known as a 'Marseillais knight'," or whatever. (Note that I still don't know what my piece's name is.)
Does such a tool already exist anywhere? I've found glossaries such as this excellent one by Stephen Emmerson for the British Chess Problem Society, but nothing that would actually let me look up a piece by "allowed moves," and certainly I've found nothing interactive.
(If, as I predict, no such tool exists yet, I'd be interested to hear about difficulties one might encounter in implementing such a tool, and good authoritative sources of fairy-piece names other than Emmerson's.)

The best tool (online, but not a web tool) was (note past tense) the list you referred to. You need to learn about movement rules (the square root notation, or x/y notation) and base piece movements, but then you can just search for movement rules. (In a few cases, you may need to update it first ...)
It is almost certainly not up-to-date anymore, though, even though it's only two years old, and that makes it non-best by the standards you set. Keeping it up-to-date as well as complete ... is probably a kind of job that very few people would do without being paid for it.  Do it once, yes. Do it for five years, ... doubtful.
Some obvious issues:
Some fairy pieces (generally called Mimics, but that term is not in the glossary as far as I can find) get their movement rules from other pieces on the board (see Imitator and Joker for two.)
Some have movement rules that separate movement and attack. In, say, Rifle Chess they apply to all pieces, and may thus be seen as a general rule or condition, but individual rifle pieces have been observed. And many of the conditions described in the glossary can also be applied to individual pieces.
So for pure movement, this might  work. But it would require the user to know beforehand that the piece is a pure 'mover', and not a mimic or another type of piece, or the lack of search find would be misinterpreted. That user is probably advanced enough to be able to go to Emmerson's list, or to Encyclopedia of Chess Problems and the relevant articles (Combined Pieces, Hoppers, Leapers, etc.), or perhaps the Piececlopedia. Even so, the probability is fairly high that the piece won't be listed.
Fairy pieces are invented fairly rapidly: a 'piece finder' would not stay up-to-date more than about ... 6 months (guess)? Encyclopedia of Chess Problems warns that its list of combined pieces is far from complete.  So there's also a management problem: someone must keep all this updated.
That also leads to the question of being 'authoritative'. As there's no clearinghouse for naming of fairy pieces, this means keeping track of names and discussions in all chess problem literature, probably to the level where actual chess problem activities would be hurt.  And one person would probably lose interest after some time, so there must be an active and working hand-over system to ensure it stays alive.  (The chess problem community is not known for doing that kind of thing well.---personal note)
I suspect that if there is a tool such as you describe, it will be short-lived. Instead, let the would-be searcher after fairy pieces create his problems without bother about terminology, and then send them to an appropriate fairy chess journal, and the editors will help with the piece names.
(I think it was J. Berger or perhaps Ph. Klett who said that unorthodox chess should be regarded as a disease. You may be seeing one of the effects of such disease ... :-)
(Added: and it just strikes me that fairy chess boards, such as grid boards, or circular boards, or torus boards would probably also add to the complexity of identifying a mover piece.)
(Added again: I would not be surprised if there already was a sub-type of fairy chess problems, where the moves are listed, and the problem is to identify the fairy piece types  and their positions that make that solution 'correct'. Hm ... )


Pal Benko's final problem EDIT: Link added

One of my chess heroes, Hungarian GM Pal Benko, is no longer with us. He overcame many difficulties in his early life to live one which was rich and full, and reached the age of 91 with his faculties undimmed. I love the clarity and variety of his problems and puzzles, and am moved by an article by another Hungarian GM, Susan Polgar, to relay his new, final composition as a tribute. First I will quote Polgar verbatim, and then give some technical comments.

  This was his final request to me, to share this Help Mate Composition
  with the Chess World!

  This is the last chess composition Pal Benko shared with me when I
  visited him and his wife at their home in Budapest last week.

  This is a a Help Mate Composition! From the starting position, White
  starts the game and checkmates Black by En Passant on the 9th move!

  In addition, the game MUST include all the SPECIAL chess moves (at
  least from one side) such as Pawn Promotion, Castling, En Passant (in
  addition to the final checkmate), and Discovered Check. There is only
  one possible solution (according to Benko himself).

  He was very proud of this Help Mate Masterpiece and asked me to share
  it with all of you! This was his final request to me.

  Enjoy!

(1) This kind of problem is known as a "synthetic", and can be very hard to solve, "a real test of chess imagination", as the veteran chess columnist Len Barden would say. It's not a proof game, but a problem with constraints.

(2) It contains a "Valladao": i.e. castling + promotion + en passant. But beyond that there is a fourth thematic move here (Discovered Check) and the constraint that these four thematic moves should be played by the same player.

(3) There is a second en passant, which delivers mate. It seems consistent with the wording that this second en passant might be the thematic Discovered Check, in which case the player of all thematic moves would have to be White. However, then White has 5 moves for promotion including e.p., 3 for second pawn, 1 for 0-0 and maybe 2 to move B&N for 0-0. That makes 10 which seems to be too many. If it's Black doing the thematic stuff: 5 for promotion including e.p. which can be discovered check, 1 for 0-0, 1 for pawn to be eped, and 2 to move B&N for 0-0. That's 9 again too many. So kB or kN must have been captured on its starting square and then got right out of the way. Maybe N captures kN and then after moving is captured by bB? (EDITED for clarity)

(4) Normally in a proof game with e.p., one can reason by uniqueness that the double pawn move must have been blocking a check, because otherwise the move might as well have been a single pawn move. But here in this thematic synthetic, that constraint is not present.

And beyond that I currently have no idea of the solution! Good luck!

No answers here, and I haven’t seen any solution in the rest of the world. So I thought I would post a work-in-progress here.

First let’s take a baby step. Which player is the one who has all these adventures?

Suppose that it’s White. Then the pawn which moves in W9 (White’s 9th move) makes 3 moves to reach the sixth rank. In addition, another pawn makes 5 moves to promote. This must have been the same pawn which executed the earlier en passant. And finally there is the castling. That exhausts 9 moves. So that means that the two or three officers which blocked the castling has to have been cleared out by Black helpful captures. Black made 2 pawn moves for en passant purposes, so that means 6 moves remain for raiding. It can’t have been a promotion because that uses 5 moves and to capture the neighbour would use the 6th, implying the promotion was to R or Q which would disturb his majesty wK. And clearly it wasn’t original R or Q which captured the officer next to wK. Capturing with N requires 4 moves to reach and 1 to retreat. So the other white officer can’t be captured. So by elimination the pieces must have been captured by black bishops. Each bishop requires 2 moves to arrive and one to run away, but in addition black’s first move did not contribute to any of this.

So we have proved that White was not the player who had all the adventures. It must have been Black.

Let’s see how the budget works out if Black is the protagonist. Black promotes, taking 5 moves including a promotion. There is 1 for castling and 1 for B8 pawn move prior to e.p. So 7 out of 8 moves are accounted for.

On the other hand White has 1 move to feed the Black e.p., 3 for the pawn which executes the White e.p. That’s 4 out of 9. But White is required to go capture at least one of the Black bank rank officers. (Another might move away using the Spare Black move.)

Could Black have castled on the queen side? In this case white must have captured two Black officers at home. With only 5 moves this can’t have been pawn or knight. Two bishops require too many moves to escape after. So at least one raider must have been R or Q. This means that the raider would capture N&B, while bQ shielded bK, and both later ran away. Can’t

Can’t quite exclude this one corner case right now, although it seems unlikely. The other, easier possibility is that Black castled on kingside.
If Black did castle kingside then the earlier argument about White castling applies. So one of the two Black officers must run from the back rank.

Therefore in either case we have exhausted the Black moves, and can conclude  that bK did not move after castling and was mated on g8 or just possibly on c8. So the final e.p. was discovered check. Since the castling rook doesn't move after the castling is complete, the discovered checkmate can't just be for bishop/queen on the diagonal. It must be rook/queen checkmate on the file as the old e.p. double checkmate is only available if the king were on 6th rank.

That all seems reasonable: indeed some actual creative thinking maybe required to progress further!


Free opening name database? Is there a database available that the gives you the names of common openings?  "Ruy Lopez", "Sicialian", "Queens Gambit", etc.  Ideally it would just be a simple map of the opening PGN to the common name.

There is an "eco" GitHub project available which I believe, based on the name, is based on the Encyclopedia of Chess Openings.

This project used to provide a JSON file with all openings, but now provides a set of tab-separated files with columns for ECO code, name, FEN, and moves.

To give you an idea of the format of the file, here's the entry for Ruy Lopez: Marshall, Main Line, Spassky Variation, which happens to be the longest opening in the file:

C89     Ruy Lopez: Marshall, Main Line, Spassky Variation       5rk1/5ppp/p1pbr3/1p1n3q/P2P2b1/1BPQB1P1/1P1N1P1P/R3R1K1 w - -   e2e4 e7e5 g1f3 b8c6 f1b5 a7a6 b5a4 g8f6 e1g1 f8e7 f1e1 b7b5 a4b3 e8g8 c2c3 d7d5 e4d5 f6d5 f3e5 c6e5 e1e5 c7c6 d2d4 e7d6 e5e1 d8h4 g2g3 h4h3 c1e3 c8g4 d1d3 a8e8 b1d2 e8e6 a2a4 h3h5


How could I defend/attack in this situation? How could I defend/attack in this situation? I feel that I'm in big trouble.

 [FEN ""]
1.d4 Nf6
2.e4 Nxe4
3.Bc4 Nxf2
4.Kxf2 d5
5.Bxd5 Qxd5
6.Ke1 e5
7.dxe5 Qxe5+
8.Qe2 Bb4+
9.c3 Nc6
10.Nf3 Qe7
11.cxb4 O-O
12.Bg5 Qxb4+
13.Nbd2 Bg4
14.a3 Qc5
15.Be7 Nd4
16.Nxd4 Qxd4
17.Nf3 Qd7
18.Bc5 Rae8
19.Rd1 Qa4

At the end I won, but thanks to my opponent, because he made a lot of mistakes.

P.S.: if anybody could give me any recommendation, to how I could defend when, the other player, moves very aggressively in the opening, it'd be welcome.

The way I see it, neither of you was aggressive in the opening -- you both tried to get rid of your pieces as quickly as possible! Being aggressive is getting many pieces in active positions quickly, not giving them away.

When we give advice, we have to take into account the level of the players. Both of you need to work on the most basic skill first: Piece safety. The first skill to learn is to recognize when undefended pieces can simply be captured, to always do that if your opponent gives you the chance, and to never give him the chance to just take a whole piece without repercussions. The moment one of you starts doing that, he'll blow the other off the board completely.

Let's show a number of positions where this was the case:

[FEN "rnbqkb1r/pppppppp/5n2/8/3PP3/8/PPP2PPP/RNBQKBNR b KQkq - 0 2"]

After 2.e4?, black can take a pawn for free, and he does.

[FEN "rnbqkb1r/pppppppp/8/8/2BP4/8/PPP2nPP/RNBQK1NR w KQkq - 0 4"]

Black gives away a full knight with 3...Nxf2. Why??

[FEN "rnbqkb1r/ppp1pppp/8/3B4/3P4/8/PPP2KPP/RNBQ2NR b kq - 0 5"]

White returns the favour immediately! Why give away a bishop with 5.Bxd5 when you could have just retreated it, say to d3?

[FEN "r1b1k2r/ppp2ppp/2n5/4q3/1b6/2P5/PP2Q1PP/RNB1K1NR w kq - 1 10"]

After 9...Nc6, black has done nothing to prevent white taking the bishop on b4! Had he played 9...Qxe2+ 10.Nxe2 Bc5 instead he wouldn't have lost a piece.

[FEN "r1b1k2r/ppp2ppp/2n5/4q3/1b6/2P2N2/PP2Q1PP/RNB1K2R b kq - 2 10"]

But white doesn't take it!

[FEN "r1b1k2r/ppp1qppp/2n5/8/1b6/2P2N2/PP2Q1PP/RNB1K2R w kq - 3 11"]

Black still ignores the threat to his bishop! He could still have played 10...Qxe2+ and then move the bishop.

[FEN "r4rk1/ppp1Bppp/2n5/2q5/6b1/P4N2/1P1NQ1PP/R3K2R b - - 2 15"]

White just played 15.Be7??, giving away his bishop. It's attacked twice (by the knight on c6 and the queen on c5), and only defended by the queen, so black could just have played 15...Qxe7 or 15...Nxe7 !

[FEN "r4rk1/ppp1Bppp/8/2q5/3n2b1/P4N2/1P1NQ1PP/R3K2R w - - 3 16"]

Instead, black insists on giving away a knight himself with 15...Nd4. If white simply answers 16.Bxc5 Nxe2 17.Kxe2, white has won a full knight.

[FEN "r4rk1/pppqBppp/8/8/6b1/P4N2/1P2Q1PP/R3K2R w - - 2 18"]

Now white is in some trouble, because he never bothered to get his king out of the center and a rook is threatening to come to the e-file, capturing the queen. There are two options: move the king away (it can't castle anymore, it moved to f2 in the opening) and defend the bishop with 18.Kf2 Rfe8 19.Rhe1. White will try to move his queen out of the pin next, say with 20.Qd1, so he's better. The other option is to take the offered rook with 18.Bxf8 Re8 19.Bb4 Rxe2+ 20.Kxe2, and white has two rooks and a bishop for the queen, which is good.

But the point is: if you see nothing of that, then you play Bxf8, because the rook is worth more than the bishop.

[FEN "4rrk1/ppp2ppp/8/2B5/q5b1/P4N2/1P2Q1PP/3RK2R w - - 6 20"]

But white didn't and we get to the end of the game, white is in trouble. But black for some reason moved the rook from a8 to e8, so that the one on f8 can still be captured.

After 19.Bxf8 Rxe2+ 20.Kxe2 Kxf8 white has two rooks for a queen and two pawns, his king is in the middle and his rooks aren't active. White is lost. But that means nothing as long as both players keep giving away pieces at the same rate as they've done so far, anything can still happen.

Edit: as AlwaysLearningNewStuff points out, in the final position white can block the attack on the queen with 19.Be3!, he's still a knight up for two pawns, and he can probably untangle his position with Kf2, Rhe1 et cetera. That's much better.


Who won the FIDE Chess Clock Contract Bidding? It should have been announced on September 23. But still, nothing on the FIDE website has appeared. Does anyone know who won in all 3 categories?

According to the FIDE website:

FIDE is pleased to announce that, in compliance with the published
Bidding Procedure, it completed the scoring of offers submitted for
the chess clock contract tender. The winners have been determined,
conditional on the manufacturers' signing binding contracts with FIDE.

So, FIDE have chosen a winner but the winners have not yet signed a binding contract.
Presumably the contract is still being negotiated.
Note this earlier link from August 2019 - https://old.fide.com/images/stories/NEWS_2019/FIDE_News/20190805-FIDE-Bidding_procedure-ChessClocks.pdf - defining the bidding process giving the following schedule:

9. Bidding Timeline
9.1 Bidding starts August 05, 2019.
9.2 End of inquiry period for bidders August 15, 2019.
9.3 FIDE publishes responses August 23, 2019.
9.4 Deadline for bidders to submit bids September 10, 2019.
9.5 FIDE announces the winner(s) September 23, 2019.
9.6 Deadline for winner(s) to sign a contract September 30, 2019.
9.7 Contract(s) shall come into force October 01, 2019.
9.8 Contract(s) effective through September 30, 2022.

According to the schedule published in August it was planned that contracts would have been signed and come into effect by now. Perhaps over optimistic on the part of FIDE.
Assuming that contracts have been signed and FIDE are keeping it secret or are too lazy to update their website would be very foolish. For a start the winners would almost certainly publish the fact widely.


Maximum number of non-pawn pieces on the board In a reachable game, what is the maximum sum of queens, rooks, bishops, knights, and kings on the board?

For queens only, see Maximum number of queens possible

@Aschultz is correct that 26 pieces is the maximum number of non-pawn and non-king pieces on the board. Since they said that they have not seen such proof yet, here it is to be seen.
[Title "me, chess.stackexchange.com 6/18/2019, Non-Unique Proof Game In 40.5 Moves"]
[FEN ""]

1. d4 a5 2. b4 c5 3. h4 e5 4. f4 g5 5. dxc5 axb4 6. hxg5 exf4 7. g4 b5 8. a4 h5 9. c4 f5 10. c6 f3 11. c5 f4 12. g6 b3 13. g7 b2 14. Na3 Nh6 15. g5 b4 16. g6 b3 17. g8=B b1=B 18. Bh7 Ba2 19. g7 b2 20. g8=B b1=B 21. e4 d5 22. e5 d4 23. e6 d3 24. Kd2 Ke7 25. Kc3 Kf6 26. e7 d2 27. Qc2 d1=B 28. e8=B f2 29. c7 f3 30. c6 Bb7 31. Bg2 f1=B 32. c8=B Bfe2 33. Bcd7 f2 34. c7 f1=B 35. c8=B h4 36. a5 Ra6 37. Rh3 Rb6 38. Rg3 h3 39. a6 h2 40. a7 h1=B 41. a8=B


Mate Prevails - Chess Rule Is "Mate Prevails" not an FIDE rule? I couldn't see it in the FIDE website but I heard about it from many players.

UPDATE:
"Mate Prevails" is a claim some players make that they win the game after 'flag fall' if they can force a checkmate in one move.

If you make a checkmating move before your flag falls, but then your flag falls before you press the clock, you win. The relevant FIDE rules (emphasis mine) are:

5.1.a. The game is won by the player who has checkmated his opponent’s king. This immediately ends the game, provided that the move producing the checkmate position was in accordance with Article 3 and Articles 4.2 – 4.7.
6.2.a. During the game each player, having made his move on the chessboard, shall stop his own clock and start his opponent’s clock (that is to say, he shall press his clock). This “completes” the move. A move is also completed if the move ends the game (see Articles 5.1.a, 5.2.a, 5.2.b, 5.2.c, 9.6a, 9.6b and 9.7).
6.3.a. When using a chessclock, each player must complete a minimum number of moves or all moves in an allotted period of time.
6.9 Except where one of Articles 5.1.a, 5.1.b, 5.2.a, 5.2.b, 5.2.c applies, if a player does not complete the prescribed number of moves in the allotted time, the game is lost by that player.


Leela Chess Zero - UCI engine What is current use status of Leela for practical player? Is it already working well as UCI? Could anybody give some insight on strength with various thinking times, especially in analysis mode? As leela uses different thinking process, I must ask also for multiPV search. Is the speed down of many PVs still as devastating as with other engines?

I have desktop with 6x3.2Ghz CPU. As graphics card like RTX2080ti is 'just' around 1300€ with good use outside of chess too, I wonder, what performance change would it mean.

With mentioned hardware, how long would approximately leela have to think to compare to Stockfish?

Stockfish 0.1s
Stockfish 1s
Stockfish 10s
Stockfish 1min
Stockfish 10min
Stockfish 1hour

Lc0 is fully compatible with UCI. It's strength depends a ton on what hardware it's being run on. On any hardware (tested down to Raspberry Pi), it will be superhuman (over 2900 elo). With a RTX 2060 ($200ish) it should be roughly even with SF on 8 cores (although you may need to mess with settings a bit to get it there). A 2080ti puts decently (20 or so elo) ahead of 24 cores of SF. The current MultiPV mode is only a display tweak. It isn't weaker, but it doesn't give as good analysis of the non-primary lines. If you have more questions, the best place to ask is probably the Lc0 discord.


Do chess coaches ever get disappointed with their students? I'm wondering if a student can disappoint their chess coach if they lose to many games for a long duration of time or any other reasons. What have been your experience as a student or teacher?

I, as a teacher of elementary age students, don't get disappointed in the students' results.  I only get disappointed if the student doesn't try.


Other than Fairy-Max, is there a variant [fairy] chess engine that is compatible with XBoard? Fairy-Max (which ships with the XBoard package) can play variant chess. Is there any other XBoard-compatible engine that also plays variant chess (and runs on Linux or *BSD)?

The XBoard Alien GUI is reputedly better suited to playing chess variants than the standard XBoard is, but that's just an observation. There are many engines that play only a few variants.
     Here's a list of engines (other than Fairy-Max) that have been noted as playing a large selection of variants and working with XBoard (Linux environment being implicit):

ChessV (plays over 50 variants)
Nebiyu Alien (a score of variants tested in homepage; many additional [user defined] .ini files available as a collective package or individually)
Pulsar
Sjaak II (Glebbeek's, not de Man's)
SMIRF


What fraction of a Pawn do the most powerful chess engines (Komodo, Stockfish, Houdini, Fritz, Hiarcs, Gull, ...) use as their evaluation unit? I've heard that the most common evaluation unit is 1/100 of a Pawn. But some engines use 1/1000 of a Pawn as their evaluation unit.

I've also heard that Stockfish used 1/256 of a Pawn as its evaluation unit (although it was 5 years ago, maybe it has changed today).

So what about the strongest and best-know chess engines: Komodo, Houdini, Fritz, Hiarcs, Gull, etc... what evaluation unit do they use?

Chess engines use centi-pawns.

https://chessprogramming.wikispaces.com/Centipawns


In an ECF tournament, how are rapid play rules different from standard play? I am interested in entering some rapid tournaments in England, and have heard that the rules for the rapid games are somewhat different than standard play rules. For example, I was told you can legally take your opponent's king if he fails to spot a check (and win the game in the process). Also, the touch-move rule does not apply - apparently you are allowed to touch a piece, take it back and play another piece - only when you press the clock does your decision become permanent.

I have picked up these hints from casual conversations at my local club - it is entirely possible that these are not really the "official" rapid play rules (ECF or otherwise) but that of a specific tournament, that these are actually blitz rules and not rapid play rules, or it may even be my club members taking my inexperience for a ride. Is my understanding of these rules correct? If I were to enter a rapid play tournament, what other differences from the normal tournament rules could I expect?

You should read the rules from this page, sections A and B. Also, I would strongly advise you to ask a referee about this just to be safe from making a mistake or from embarrassing yourself. You can come earlier before the game starts ( 1 hour will be enough for the referee to explain you everything you need to know and for you to have time to relax and psychologically prepare for the game ) and just ask him/her to explain you what you want to know ( it would be wise to write down your questions ).

  I was told you can legally take your opponent's king if he fails to spot a check (and win the game in the process).

I haven't had such a case, but if the opponent plays illegal move you can stop the clock and claim a win-see the rules in the section A in the link I posted.

  Also, the touch-move rule does not apply - apparently you are allowed to touch a piece, take it back and play another piece - only when you press the clock does your decision become permanent.

No, that is not the way I remember. If you touch the piece you must play with it but your opponent can hold it in the air / drag it over the board / continuously put it on the board-pick it up-put it on another square, until he presses the clock. This is very rude behavior but is allowed.

  If I were to enter a rapid play tournament, what other differences from the normal tournament rules could I expect?

Read the rules from the link I posted above, and talk to the referee before the tournament just so you can be sure and safe.

This is all I know, I haven't played blitz for 11 years-that is why I have advised you to talk a little with the referee.

If you have further questions leave a comment and I will try to help.

Good luck on your tournament!

THIS EDIT CORRECTS MISTAKES POINTED OUT IN COMMENTS BELOW:

I will just quote member Remco Gerlich :

About illegal move ( emphasis is mine ):

  In rapidplay, an illegal move does not lose the game. The same penalties as in slow play apply (have to take it back and move with the touched piece, opponent gets 2 minutes extra on the clock, 3rd time in the same game is game loss). The difference with slow chess is that in rapid you must claim before you make your own move, in slow chess the position will always be reinstated no matter how long ago it happened. Illegal move is only a loss in blitz chess (section B).

About making a move according to the rules:

  Also, no you can't keep moving your piece until you press the clock, you can keep moving it until you let go of it.

Best regards.


Do major chess publishers use custom software for typesetting chess books? As I try to understand how one would publish a large chess book, it feels that chess gives some pretty custom requirements for an editor or publisher. I am pretty sure that chess authors use Chessbase or similar software for writing their books and then pass them off to editors who proofread and do all the final layout and typesetting for printed version. Since Chessbase does not support proper document management (export to RTF is as far as it goes), and layout software like InDesign don't support adding chess diagrams, do software publishers like Gambit, Everyman chess, Quality Chess, etc have their own chess aware custom publishing tools? Or do editors just use regular publishing software and then insert diagrams by hand to optimize for page space as they see fit, with plenty of room for manual errors (i.e. inserting diagrams that don't match the moves)?

This is less a question about chess, than a publishing question.  The answer is:

No.  The publishing industry largely uses publishing software (open source, and proprietary) to publish books, including chess books.  You've named one - InDesign.

Software such as Adobe's InDesign or Open Source software such as SILE or LaTex can lay out a book given the correct font.  Fonts can be used with Typesetting software to represent positions and pieces.
For example a common book font is Chess Mérida:

This font also includes black backgrounds and pieces on backgrounds so you can make images such as:

The font converts that from the text:
!""""""""#
$tMvWlVmT%
$OoOoOoOo%
$ + + + +%
$+ + + + %
$ + + + +%
$+ + + + %
$pPpPpPpP%
$RnBqKbNr%
/(((((((()

(Download the font here and cut that text into a Word Document and change the text to the Chess font and see for yourself)
You can find many chess fonts to use with your publishing software here.


Find an opening based on the position of one player only Given a position for just one player, how can I check to see if there is a standard opening that leads to that position?
For example, how could I find if there is an opening that leads (or may lead, if the line is followed by black) to a position like this for white?
[FEN "8/8/8/8/3PP3/2P2P2/PP4PP/RNBQKBNR w KQ - 0 1"]

Using my free, open source pgn-extract program you can specify a grep-like FEN pattern to be searched for in a PGN file of games. The program comes with a file of opening lines (eco.pgn) so a search such as:
pgn-extract --fenpattern "*/*/*/*/3PP3/2P2P2/PP4PP/RNBQKBNR" eco.pgn

would output any matches along with the associated ECO information in the tags. I didn't find anything for this particular pattern.


Mac/iOS chess app with rates option I am looking for a chess app that you can set an exact rate to play against the computer (same as you have in chess.com where you set it to play against others).

Is there any Mac (specifically) and iOS app where you can:

play computer and choose the exact rate of the computer
have some kind of analysis of your game

It must be an offline app.

I'd like to recommend my own iOS app, SmallChess and SmallFish. They have time controls and playing strength.

In addition, there are many many other similar apps on the market. A simple "chess" keyword search in the app store will give you many results.

For MacOS, the Stockfish MacOSX program is good.


Endgame books or web-sources What books or web-sources have people worked with to improve their endgame?

I have gone over Silman's Complete Endgame Course: From Beginner to Master and
Understanding Chess Endgames.

I feel good about major piece endings but I am still tripping over BN vs NN or BB endings.

Any thoughts, pointers?

A very interesting source is 100 Endgames You Must Know by Jesús de la Villa. Jesús focuses in most common endgames, with a very practical approach and only 100 pages (Spanish version) long. I miss the K+Q vs K+R ending here, but it's a very recommendable book.

More comprehensive books, and also longer and more dense, are Fundamental Chess Endings by Muller and Lampretch and Dvoretsky's Endgame Manual by Dvoretsky. I've actually used the first one to check missing endgames in de la Villa book, as the K+Q vs K+R.

These books are about theoretical endgames. Also both Dvoretsky's School of Excellence and Jacob Aagaard Grand Master Preparation series have a book each about practical endgames play. I have read none of them, so I cannot give you my impressions about them.

Another interesting book is Practical Rook Endings by Mednis, focused in rook endings that, as you know, are the most common ones.

My personal advice is to start with de la Villa Book, to have Muller or Dvoretsky's manual as a reference (at least I cannot afford to study them), and study a book about practical endings.


How to improve on the early endgame? The late middlegame/early endgame is by far my weakest point.

I often get some kind of advantage in the opening, but then struggle to convert. I do study endgames, for example I am currently reading Silmans Endgame Course. But the point is that these kind of endgames that you can learn by rote memorization/technique (e.g. say Lucena Position, or K+P vs K etc.) is not what I struggle with. It's rather to find the right plan in positions, where there are many more pieces on the board.

I try to give an example by some positions that I encountered in tournament games, e.g. longer time controls. I hope this explains better in what kind of positions I struggle.

r1r3k1/ppp2pp1/2q2n1p/4B3/8/2Q4P/PPP2PP1/3RR1K1 w - - 0 19

1. Qxc6 bxc6 Bxf6 gxf6

I noticed by exchanging pieces, that black will end up with several pawn islands and double pawns. But I failed to convert. Later

8/p1p2p2/1rp2k1p/4Rp2/1PP2P2/P6P/6P1/6K1 w - - 0 29

1. Kf2

instead of Ra5, forcing on exchanging rooks, or attacking both the a and c pawns. I simply didn't have a proper plan here and what to do - so even though I can calculate, I did not know what to calculate. In this game black managed to ourmaneuvre me and I could barely hold a draw.

8/1p1k1p1p/2n1p1p1/p1P5/1pK1PP2/1P6/1B4PP/8 w - - 0 36

1. g4?

here I played g4? instead of seeing that I can invade with Kb5, and then Black is stuck with defending his a-pawn so that his Knight is almost not moveable. After Na7 I lost instead of securing a draw.

3r4/8/2Rnk1p1/7p/1P1p1B1P/2p2P2/5P2/6K1 w - - 0 40

1. b5??

which Black can answer with Kd5 and wins. I played b5?? instead of getting my King in the game with Kf1, which would have rescued the game.

In these positions it seems crucial to find the right plan before calculating anything. Typical endgame books kind of don't bring me forward I feel.

What kind of learning ressources and or methods can you suggest to improve in such kind of positions?

The English GM Glenn Flear has coined the phrase "not quite an endgame" or NQE to describe exactly the kind of positions you talk about. He has written a book, "Practical Endgame Play - Beyond the Basics: The Definitive Guide to the Endgames That Really Matter" about these. It covers NQEs where each player has pawns and only two pieces.

Unfortunately it is out of print but you may be able to find it for sale second hand.


What sort of strategies unfold on this elongated board? I recently found this incredibly elongated chess board on the /r/gaming subreddit, with this image:

There was a comment thread discussing the potential strategies of playing on this board, with some consensus that rooks and queens become much more important due to their ability to attack from across the board, and that the 50-move rule would be triggered due to the size of the board.

Is this the only viable strategy for this sort of board?

As soon as you change the chessboard in chess, you have to re-assess the relative value of the pieces, as a piece's value is directly affected by its mobility and scope. Note that this is already the case in game on the conventional 8-by-8 boards since how much activity our pieces can benefit from depends on how much space we control, which itself depends on the pawn structure, etc. So in any game, the relative values are changing constantly based on the configuration of the pieces. Thus, to answer your question about finding viable strategies, we first have to develop a good feel for how the values of our pieces are being affected when placing them on a longer board.

What we seem to have is an l-by-8 chessboard where l denotes the length of the elongated side (units being a square's side, or simply the count of squares). Since we've only scaled one dimension of the board, here the vertical one, then only pieces that move vertically (or generally laterally) can benefit from the scaling of the board, as they gain mobility (number of legal moves available to them) proportionally to l. The only pieces that satisfy this kind of movement are the queen and the rooks, so clearly:

Rooks and queens are the most important pieces here and have a higher relative value to the other pieces (for l>8) w.r.t the known relative values on a 8-by-8 chessboard.

So in short, the scope of our queens and rooks become greater on the longer board and whatever strategy we adopt, should emphasise the activity (and protection) of these pieces, specially early on if we are to achieve any small advantage.

Now let's see how much the other pieces are affected:

Bishops: since we don't scale the board in both dimensions (and thus not changing the long diagonals), bishops's scope remains roughly the same. For example, when centralised they will have at most 14 legal moves on an empty board, while they have 13 on the 8-by-8. Moreover, they will have to go through a long zigzag across the board until they see the opponent's pieces (so they cost many tempi). Most importantly, we no longer have long diagonals that span the board, i.e., bishop fiachetti are much less meaningful now since they cannot eye the opponent's kingside or queenside, let alone taking away squares from their camp. So bishops, despite being still fast pieces, seem to be less effective on a longer board.
Knights: Knights as always are rather very slow pieces, and here it's the same. So naturally, for their activation they will cost us even more tempi that the bishops. Moreover, their scope is not affected by the scaling of the board (it would if l<8). So everything being the same, just placed on a longer board, will render knights into even slower pieces, thus their relative value suffers as well w.r.t the 8-by-8 case. Lastly, knights are particularly good when they can be estalished centrally and on permanent outposts: i.e. a square that is well covered by our own pawns but impossible to attack by our opponent's respective pawns. However, since the longer board means the pawns take l times longer to advance to anywhere near our opponent's camp, we will not be able to create meaningful outposts for our knights anytime soon. So, early on specially, knights seem to be rather useless.
Pawns: as already hinted at in the previous point, pawns will be ever slower the longer the board is. This means for a good chunk of the early game, we cannot secure any valuable space with our pawns. More importantly, there are no pawn moves that take away squares (and thus options) from our opponent's camp at the beginning, which makes a strong case for the fact that on an l-by-8 board with l much larger than 8, white's extra tempo becomes negligible and the game is already equal from the get-go. For the contrasting case of 8-by-8 see e.g. the discussions here.
Kings: King safety becomes funny to judge now, on the one hand, one can argue the king is even safer on the l-by-8 since our opponent's pieces are so far away which makes it very difficult for any threats to be made, which gives us lots of tempi to re-arrange our pieces however we want. On the other hand, if we are to start a long journey with our pieces to eventually reach the opponent's side, our king might be left stranded far away from our coverage and thus rather exposed (e.g. as soon as bishops, rooks and queens can sneak through the structure to reach our king). And if all this means that we need to collectively move our pieces towards the enemy, so they can constantly eye one another, then our advancement speed is bottlenecked by that of the king's... What is roughly the same, is the fact that the board still has edges, so castling our king so it can be tucked away to a corner and only accessible from one side is still possible, but how much of protection that offers, is hard to judge.
Rooks and queens: We have already covered those in the starting discussions.

So in a nutshell, our reassessment of the pieces is:

Rooks and queens are made even stronger relative to the other pieces.
Knights and pawns are made weaker since their mobility is not affected and they have only become slower (since it takes longer for them to cross the board and reach the opponent's side).
Bishops are neither here nor there: their scope is roughly the same (e.g. in terms of legal moves) but they are still quite fast pieces, and with a few zigzags they can cross the board and create threats or coordinate eventually with our heavy pieces. So they remain strong, but less than their worth on an 8-by-8 board since there are no long diagonals spanning the board. But clearly among minor pieces, they are definitely much stronger than knights on the elongated board.

Two basic strategies to consider:

Now that we have a better idea for how the relative value of our pieces is being affected by elongating the board, we have a better chance of finding good strategies. The obvious things that come to mind:

Use your early tempi to quickly activate your queen and rooks in order to already pose threats to your opponent, e.g. by being the first in having an active rook, you will be the first to slow down the advance of your opponent's pawns, and that ought to be your first easy way of gaining a small plus.
Once your heavy pieces activated, I see two separate options: (1) creating a small squad and moving that towards the opponent's side or (2) moving collectively all of our pieces across the board, which is safer since our king is less likely to become stranded compared to (1).

Let's delve bit deeper into each:

In (1): say your two bishops, the two rooks and the queen, that's a 5 piece squad that can coordinate an attack against your opponent rather quickly, either to win material, or to try and bait tension on one side, and sneak through on the other side with a heavy piece. Infiltrating behind your opponent's pieces and winning potentially lots of material, this is more the middle game since we're assuming our opponent's pieces are somewhat close to the center of the board. Admittedly, this strategy resembles more what typically occurs in the strategy game Stratego, where pieces have well-defined ranks which acts as their strength (a lower rank cannot capture a higher one etc), and thus, one typical strategy is to infiltrate our opponent's camp with a small squad of high ranked pieces and mop up their pieces (assuming we know where the bombs are...).
In (2): ultimately, once the gap in space between our pieces and our opponent's have become smaller, the gameplay will approach that of the conventional chess on an 8-by-8 board, and thus we can adopt our usual mindset and conventional strategies become viable again, which means we'll have a more normal game than in (1).


Extracting features from chessboard So i am implementing an intelligent chess agent with the use of reinforcement learning.I intend to use Java.

After reading the master thesis of H.Mannen i decided to use some of the features listed on Appendix B of his master that can be found on page 67.

Edit- Description of the features:

-Board control : amount of empty squares controlled by a side

-Connectivity : amount of connectedness between the pieces of a side

-King’s distance to center amount of squares a king is separated from one of the center squares e4, d4, e5, d5

-Total mobility : total sum of squares reachable by a side

-Center control : amount of pawns occupying the squares e4, d4, e5, d5.

-Isolated pawns : amount of pawns without a pawn of its own side on an adjacent line.

-Doubled pawns : amount of pawns, greater than 1, on 1 line.

-Passed pawns : amount of pawns without an enemy pawn ahead of it on the same or an adjacent line.

-Pawn forks : amount of pawns which attack two superior pieces.

Due to the fact that my project is focused on the AI part of the chess agent i would like to use some preexisting open source Java libraries or functions that automate the proccess of extracting these features from the chessboard.

After searching, the only thing i found was Chesspresso but it comes with no tutorial and i was unable to find one. So i have two questions:

-Do you know any good tutorials for Chesspresso?

-Are aware of any Java open source library that will help me extract the features i want from the chessboard so i can reduce the programming cost of the project?

Thanks in advance.

While I certainly don't know every Java library for chess, I'd be surprised to see a library designed to extract features like what you describe. There shouldn't be one because nobody else needs it.

Fortunately, everything you said is implemented and more or less there, but you'll have to do some works. You should consider to use an open-source project that has bitboard implemented (such as Droidfish or any Java engine uses bitboards). You'll need to learn how to use bitboards, but you'll find it useful to do what you want to do.

For example, you can get total mobility by masking the attacking pieces with the opponent pieces, something like:

(squares attacked by my pieces on an empty board) & (their pieces)

As another example, we can get board control by:

(squares attacked by my pieces on an empty board) & !(squares attacked by their pieces on an empty board)

For the documentation on Chesspresso, I doubt there is anything better than it's Java docs. You'll need to learn to read their documentation.


How do you teach chess to a beginner / rookie? Recently, I got some students (beginners) in chess, and I would like to teach them how to play but I don't know where to start! They already know how to move pieces and some concepts on how to play, but still they are rookies. Where can I start from ?

I have a couple of suggestions, some tried and true, others more experimental using modern technology.

1. Start from the endgame

Pros

Starting backwards will allow the player to understand chess at a deep, fundamental level
If you learn the endgame first, you are constantly moving toward a place you are comfortable with when you play the game (as opposed to a middlegame player, who is constantly moving away from his comfort zone)
The endgame is grounded on the concrete, but requires sound positional understanding to play well, thus learning it allows you to learn all aspects of the game

Cons

It can sometimes be tedious to teach and learn the endgame (I'm having this problem myself)
It requires a lot of initial investment from the student, for what seems to be little return (they may get caught by tactics, or opening traps in OTB games, making them discouraged)

2. Teach a thinking algorithm

Basically, create a simple step-by-step process (allow the student to come up with their own and then help them tweak it) which aids in making decisions OTB (i.e moves).

Pros

Very easy to do and has almost immediate results (an anti-blunder check at the end of every move goes a long way to improve one's game)
A fundamental skill which is necessary for every phase of the chess game
Can be built upon as more knowledge about the game is garnered

Cons

None, except for the fact that you aren't focusing on any one thing in particular

3. Tactics, tactics, tactics!

This is more experimental and involves drilling tactical puzzles (I recommend this book, the puzzles are beautifully arranged so that they build on one another) until they can be done "by hand" (i.e directly from memory).

Pros

All the benefits that tactical training provides, including:

Able to handle complex positions with little difficulty
Increase in visualization abilities
Confidence in one's own moves (i.e that they won't be subverted by a missed tactic)
General decrease in blunders and increase in noticing opponents blunders

Memorization of the positions, allows the creation of "building blocks". These are useful because you can often simplify complex positions in these basic blocks
Its just more fun to explore tactical fireworks

Cons

Focusing on just tactics, does not give a true understanding of the game, which is really more important for future success
There is a diminishing return, after which no amount of drilling will help
It can be tedious


How to determine the value of a chess set? I'm buying this set.

It looks expensive, yet it's cheap. So how to determine the value of a set? How much does a first class set usually cost? Does it include a timer or any accessories? Are there famous manufacturers like D&G in clothing? And what are the most expensive sets ever?

The value of a set can be pretty arbitrary. Things that affect the cost of a set include:

the materials from which it's made
the amount of skilled hand-work
the quality of the components
its rarity
size
accessories

The travel set you posted is unremarkable with respect to the attributes above:
 - it's plastic
 - none
 - historically low
 - not at all
 - small
 - magnetic board and carrying case.

Now, the same set coming from, say Germany, would get similar remarks except for the "quality" rating. I'd expect that a set from Germany would be made of better components; thicker plastic, better glue, and more careful assembly.

Now, value is a tricky beast.  The hypothetical German set I mentioned might cost $30. The Chinese set could have the same or better value.  You won't know until it is in your hand. For $17, you'll probably have a set you can use for a year or two.  Who knows, though, it could be amazing and last forever. Or it could arrive broken. Who knows.

I don't know much about travel sets.  A webs search should tell you what's out there. Then you can compare features.

I think the most luxurious sets are coming out of the House of Staunton.  You'll see some amazing sets there. Be prepared for sticker shock.  My personal insane favorite would be the set made from mammoth ivory.

Bigger is not always better, rarer materials are not always more practical, fancy is not always better than simple. HoS has more affordable sets, though many would not consider them so. The Reykjavik set has always been a favorite of mine. Boxwood and ebony are to me the perfect woods and a 3.75" King is the perfect size. The design is clean. It's $350.

What makes these sets a good value is that the wood used is rare, suited for the task, and of high quality.  The workmanship is where it needs to be. Skilled people are carving the knights (in some cases), the size is correct, the weights are correct, the styles are correct (don't take your Star Trek themed set to a tournament...), and they simply feel good to touch.


What are the laws concerning copyright of chess games? Here is my specific situation: I have written a novel in which two characters play a game, the moves of which follow exactly a known game between two ranked players in ChessGames.com. Must I get permission from the two real players? Or must I only credit them in the acknowledgments of the novel? Or need I even do that? Any information, especially with legal citations, would be greatly appreciated!

Chess games without annotation can't be possibly copyrighted. You don't need to inform them. You don't need to acknowledge them.

I've been using Carlsen's games (without annotation) for commercial. I literally sell his moves and the games. So far, the world champion has not complained.

Game annotations are protected by the laws. Make sure you only use the game moves.

@itub has some links, such as:

https://chess24.com/en/read/news/us-judge-agrees-with-chess24-on-chess-moves


Positions that stump engines Chess engines are so strong that it is becoming increasingly hard to find positions that they are demonstrably evaluating incorrectly. I'm interested in collecting examples—if there are any—of positions where we know the correct evaluation, but that are very difficult for engines.

Below is a beautiful study that I encountered recently in Chapter 5 of the book Barrycades and Septoku: Papers in Honor of Martin Gardner and Tom Rodgers, by Thane Plambeck and Tomas Rokicki (eds.), MAA Press, 2020.

[Title "Carlos Pereira dos Santos, White To Play And Win"]
[FEN "bR2r3/2nK4/kp1pp1pp/p1R2p2/1P1P1P1P/p7/P2P3P/8 w - - 0 1"]

The engines I have access to are old and out of date, but after 1.b5+ Ka7 they want to play 2.Rxe8? and miss the winning continuation 2.Rxa8! Nxa8 3.Rc8! Rxc8 4.Kxc8 with a win for White. I would be curious to know if stronger engines are able to find this win.  [EDIT: Thanks to Oscar Smith for pointing out that I can download Stockfish 11 for free. It had some difficulty at first, but after searching about 2.5 billion nodes it finally found 2.Rxa8!]

Years ago, there was a ChessBase article on this topic.  They give some examples of positions, such as fortresses, where the engines' numerical evaluation is way off.  However, sometimes the engine plays the position correctly anyway, finding the drawing moves even though it thinks it's losing, and such examples are not so interesting to me.  What is more interesting to me is a position where the engine loses a position that a perfect player would draw, or draws (or even loses) a position that a perfect player would win.

Probably the best example from that article is a study by Behting, shown below.

[Title "K. K. Behting, Baltische Schachblätter 1908, White To Play And Draw"]
[FEN "8/8/7p/3KNN1k/2p4p/8/3P2p1/8 w - - 0 1"]

As of 2012, careful analysis demonstrated that the study is sound but that engines had serious trouble with it.  Is that still true today?  [EDIT: It seems so; after searching 25 billion nodes, Stockfish 11 was still unsuccessfully trying the 1.Ng7+ line that is analyzed in detail here.]

There is one other type of example that I know about, namely tablebase positions where White has an extremely subtle win.  For example, below is a position that I found on Wikipedia.

[Title "Lomonosov Tablebase, White To Play And Win"]
[FEN "8/r6n/2Q5/8/5k2/3K4/7N/3b3q w - - 0 1"]

Clearly, if an engine without tablebases plays White and an engine with tablebases plays Black, the engine playing White is not going to win.  Sooner or later it is bound to blunder away the win.  I would be curious if there are any humanly comprehensible examples of this type.

In the process of typing up this question, I found another question on this site that asks a very similar question.  Unfortunately, some of the answers there seem to be (no longer?) valid.  Also, let me emphasize again that for my purposes, a fortress position that the engine thinks is losing but that it plays correctly anyway does not count.

In short, my question is this:

  Are there other good examples of positions that stump engines?

There are plenty of positions that stump engines, and it's not too difficult to find some from engine tournaments. Example, this position stumped Stockfish:

[FEN "1k1r4/pp4pp/4pb2/2Q5/2P5/8/P5PP/6K1 w - - 1 28"]

Stockfish actually reached +2.76 eval later, even though White has no way to break through. In fact Black can afford to give up the e6-pawn and the position is still drawn. Lc0 evaluated the position accurately as a draw, which doesn't mean Lc0 is some kind of goddess at evaluating fortresses, since this position stumped Lc0:

[FEN "5k2/5p2/p3pPp1/3pN2p/b6P/2P5/P5P1/7K w - - 0 35"]

Black plays ...Bb5 and defends along the f1-a6 diagonal, and White will never get anywhere, especially since if the Knight moves too much Black advances the e6-pawn with counterplay. This time Stockfish accurately assessed the position as drawn, while Lc0 was at +1.6 - or about 60% chance to win - or so for quite a while.

If you're wondering about positions with study-like solutions that humans think is pretty - that's a different question.


Chess books about how to deal with time troubles Do any of you know if there is any book that is written about the theme "How to deal with time troubles"? It does not need to be only about time management, but at least if it has something on that topic it would be great to have the title of it. If there are any examples from real games it would be excellent.

There are a lot of books that tackle the problem of time trouble at least somewhat. I would recommend The Seven Deadly Chess Sins by Jonathan Rowson. It's not solely about time trouble but touches upon time trouble often enough to be definitely useful in that regard.


A simple free opening editor? I am looking for a simple and free opening editor where I can save openings and variations.  I know Chess Position Trainer is free, but I am looking for something much more simple.

You can go here: http://www.caissa.com/chess-tools/pgn-editor.php and select the tab "2. Game Moves", then make your moves. The fourth tab will show the fen and the pgn of the game.

As far as where to store them, create a folder somewhere named openings, and save each different set of fen/pgn as a text file with the output.


Chess GUI with Time Handicap for Engine vs Engine matches I want Stockfish to play for 1 hour per move and I want Komodo to play for 2 minutes per move. Is there a GUI that can do this?

Arena has the option to set the seconds per move but both engines will have the same time control. I want a different time control for each engine.

Arena can do this!

Suppose a game has a time control with x minutes for y move(s). In your case you need x=2 for Komodo and x=60 for Stockfish. You achieve this by doing the following:

Go to menu Engines > Manage and in the tab Details find each engine in the left panel Installed Engines. In the right panel Selected Engine go to the tab Special and change the value for Strength(%). In your case, when starting a game with 60 minutes for 1 move, the adjusted strengths would be:

Stockfish 100%; resulting in 1*60 minutes for 1 move
Komodo ~3%; resulting in 0.03*60 minutes for 1 move


What is a good opening software program? I am trying to find a good program to help me perfect my opening play. It needs to be something simple because I am no computer expert. I don't understand the opening trees and all that high tech stuff. I was wondering if there was any program that lets you make moves and it tells you what opening you are using and shows the most popular responses and right and wrong moves. If you could provide in your answer what it is exactly that the program does and how you use it I will greatly appreciate it. If it matters my rating is 1430.

Try 365chess.com Chess Opening Explorer.

Gives number of games win/lose/draw statistics and shows what opening was played. You can also click into a game for the moves when the tree gets down to one game.


Why do people say today's chess is dominated by computers? Everytime I read articles on chess, I see people who say that chess nowadays is dominated by computers. For example if you look for a thread on the subject 'fischer vs carlsen' (just an example) you see people comment that if fischer had access to computers, he would have been better. Why? What do modern GM's do with computers?

Masters use computers as training tools.  They allow a master to quickly check the viability of variations and understand why some moves are good or bad.  Further, they afford searchable instant access to millions of positions and countless openings to the master.

In short, the computer is your sparring partner, second, and librarian, and who works for cheap.


Is the expression 'fixing pawns' or 'fixed pawns' - a proper term to describe blockaded pawns? I feel this 'fix' terminology may have come as a direct translation from Russian chess literature (so I see it used in Dvoretsky's books); is 'fixed' really a proper English term to describe pawns that are blockaded (especially in the endgame) by opponent's pawns and have little or no chance of advancing?

Often pawns are "fixed", it's more than them just being blockaded.  For example assume Black's pawns are on b7 and a6.  If White pushes his a-pawn to a5, he is fixing the b-pawn on the b7 square, since it's backwards and can't move.  However, in this example no one would really think White's also "fixing" the a6 pawn, even though it's blockaded.

But then you have another case like the following: suppose Black has an isolated pawn on c5.  If White pushes his c-pawn to c4, many would say he is fixing the weak c5 pawn, so that it can be easily attacked.

But assume Black had two extra pawns on d6 and e7, forming a pawn chain from e7 to c5.  If White played c4, I doubt there would be many that considered White was "fixing" the c5 pawn.

So, when someone says "fix" they are most often talking about when you keep one of your opponent's weak pawns from moving.  This is just arbitrary terminology though, and I don't think saying a blockaded strong pawn is "fixed" is wrong.


What are the biggest events in chess by viewership? I realise chess viewerships have skyrocketed due to organic growth in popularity, and especially due to more people being stuck indoors in the last year.
Are there statistics on how many viewers each chess tournament receives, and if so, what are the biggest chess tournaments by viewership (including online viewers) in recent years?

Please note, this does not answer the question, but I find this information gives some helpful clues. This is twitch daily viewerships of all chess channels combined for the past 5 years. It shows peak and average daily viewers. But it doesn't say what the events were corresponding with the heightened figures.

Source: https://sullygnome.com/game/Chess/1825/summary


Is capturing on empty square with a pawn legal? How is it possible to move c4 to b3?

This type of capturing with pawn called capturing en passant.

Here's the rule explained on Wikipedia:

  When a pawn advances two squares from its starting position and there
  is an opponent's pawn on an adjacent file next to its destination
  square, then the opponent's pawn can capture it en passant (in
  passing), and move to the square the pawn passed over. This can only
  be done on the very next move, otherwise the right to do so is
  forfeit.


How is a perpetual check reached in this puzzle? This puzzle on chesstempo caught my eye. We play as White:
[FEN "4Q/4p1bk/1p1qp2p/p1p1n2B/4P/2P3B1/PP4P/6K b - - 0 1"]

1. Nf3

Side Note: The answer is of no importance here, so no spoilers from me. :)
The puzzle is tagged with avoiding-perpetual, yet I cannot see the perpetual check here. It has been discussed in the comments under the puzzle:

Why not just gxf3 and after Qxg3+, run away with the king to the left board edge and hide between pawns?
Because he can’t hide. When the king reaches c2, the black queen attacks from e2. When the king is on b3, the queen moves to b5, and perpetual.

However, I do not think this is quite right. b5 is protected by the White queen.  So, where and how is perpetual reached on this board? I would appreciate a hint instead of the full solution. :)

I think that Kf2 is actually the winning move for White and the perpetual results after gxf3.
[FEN "4Q/4p1bk/1p1qp2p/p1p1n2B/4P/2P3B1/PP4P/6K b - - 0 1"]

1. Nf3 gxf3 2. Qxg3+

Now the White king can not escape the perpetual even though the Black king is very close to checkmate.


The most efficient valid move generation for minimax Problem
I am creating a chess engine in Python using Minimax algorithm (with alpha/beta pruning) but I have some issues with performance. Currently the thinking time looks something like this for a mid game position:

Depth 1: 0.01 s
Depth 2: 0.07 s
Depth 3: 0.76 s
Depth 4: 19.8 s

I have timed each function and here are the worst performing functions, time is per move at depth 4:

get_valid_moves (10 s)
deepcopy (8 s)
get_all_possible_moves (8 s)

What I have tried
I have tried to have the board represented as a 2D array (8x8) which is the easiest solution. With a 1D representation (10x12) I got a tiny bit better performance but not enough to increase depth.
What I need feedback on
Before I try to optimize my minimax function with transposition table lookups and such, I was hoping to have the most efficient way of calculating valid moves and all moves. Here is the process I currently use:

Looping through 8 directions from the king location to find if I am in check and what pieces are pinned (8x8 loop)
Get all possible (pseudo?) moves without considering checks or pins (8x8 loop to find all pieces on board and then add each pieces possible moves to a list)
Get valid moves by seeing if I am in check or double check (removing moves from the all_possible_moves list if they are not legal)

Here is an example of how I calculate possible moves for a piece, bishop in this case:
def get_bishop_moves(self, row, col, moves):
    piece_pinned = False
    pin_direction = ()
    for i in range(len(self.pins)-1, -1, -1):
        if self.pins[i][0] == row and self.pins[i][1] == col:
            piece_pinned = True
            pin_direction = (self.pins[i][2], self.pins[i][3])
            self.pins.remove(self.pins[i])
            break

    directions = [(-1, -1), (-1, 1), (1, -1), (1, 1)]
    enemy_color = 'b' if self.is_white_turn else 'w'
    for d in directions:
        for i in range(1, 8):
            end_row, end_col = row + d[0] * i, col + d[1] * i
            if all(0 <= x <= 7 for x in (end_row, end_col)):
                if not piece_pinned or pin_direction == d or pin_direction == (-d[0], -d[1]):
                    end_piece = self.board[end_row][end_col]
                    if end_piece == '--':
                        moves.append((row, col), (end_row, end_col))
                    elif end_piece[0] == enemy_color:
                        moves.append((row, col), (end_row, end_col))
                        break
                    else:
                        break
            else:
                break

Board 2D respresentation:
start_board = np.array([
            ['bR', 'bN', 'bB', 'bQ', 'bK', 'bB', 'bN', 'bR'],
            ['bp', 'bp', 'bp', 'bp', 'bp', 'bp', 'bp', 'bp'],
            ['--', '--', '--', '--', '--', '--', '--', '--'],
            ['--', '--', '--', '--', '--', '--', '--', '--'],
            ['--', '--', '--', '--', '--', '--', '--', '--'],
            ['--', '--', '--', '--', '--', '--', '--', '--'],
            ['wp', 'wp', 'wp', 'wp', 'wp', 'wp', 'wp', 'wp'],
            ['wR', 'wN', 'wB', 'wQ', 'wK', 'wB', 'wN', 'wR']])

Final questions
Is there any way of doing the valid move generation differently (without using bitboards)? Am I overlooking something? It is not fun to work on the evaluation function when my engine doesn't reach more than depth 4... :)

You should not stop after figuring out where the bottlenecks are, you should go on to identify them.  For example, do you invoke the get_xxxx_moves() every time around?
On the chance that you do:
Instead of listing all moves each time,  you may be able to reduce the work needed by
only updating the piece move lists that are affected by a move.   The other pieces (status and valid move lists) are unaffected, and don't need recalculation.
Thus, the opening move e2-e4 only affects pieces that cover/attack the start square e2 (wQ, wK, wBf1 and wNg1), so those are the only recalculations needed.  Nothing covers/attacks e4, so no more work to do right now.
And so on.
Bitboards can be more efficient, but as you explicitly said to exclude those, ...


Where to download a 6 man Nalimov endgame tablebase? Can anyone tell me whereabouts I can download a 6 man Nalimov endgame tablebase? I've seen some websites with 6 man Nalimov (case in point: http://contentdb.emule-project.net/view.php?pid=1630). However, so far all I have come across is dead links.

Can someone able to point me to some working link(s)?

From the ICCF site:
Players who wish to have access to the 7 men tablebases may purchase any of the following programs: ChessOK Aquarium 2017, Houdini Aquarium 2017, Houdini PRO Aquarium 2017, Chess Assistant 17 with Houdini 5  and Chess Assistant 17 PRO with Houdini 5 PRO.

Free Android application
One more way to access 7-man tablebases without having a key is to use Android application.

Search for Lomonosov Tablebases or use https://play.google.com/store/apps/details?id=com.convekta.android.lomonosovtb

Alternatively, if players only want access to 6 men tablebases they may visit this page to use the 6-piece Nalimov tablebases: http://chessok.com/?page_id=361


How to decide what openings to stick with? I've come to the conclusion that I'm at the point where it would be better for me to stick with a handful of openings I can know well as oppose to how I would normally just play quite a large range of openings. My question is how I would find out what openings suit me since I plan to constantly play them because honestly with so many openings it feels difficult to choose. For instance I can't decide whether I prefer e4 or d4? Also I don't really have an "official" repertoire against openings that aren't d4 or e4 such as g3/g6 or b3/b6 openings, is this an issue? I normally just follow opening principles (control the center, develop etc.) to get by those openings.

Yes, it is better if you concentrate on just a couple of openings. Even though it feels difficult to choose, you should know if you like closed positions (then, generally speaking, play 1. d4 as White, and choose e.g. French and the King's Indian as Black) or open positions (when it makes more sense to play 1. e4, and e.g. Sicilian and the Grünfeld). If you have no preference, check your results - play the openings which you were successful with in the past.

Although, to become a better chess player, you need to practice all types of positions. (But not all openings.)

To answer your last question: if your opponent plays an 'odd' opening, you should indeed be fine if you develop along the general principles (but watch out for sudden tactics).


What is the correct placement for the King and Queen on the chessboard? What are the correct placements for the King and Queen set up on the board? I've heard things like, "white on the right and queen on her own colour" and "kings must not be facing each other." I'm sure its just an exact mirror on both sides; am I correct in placing the white square on the right and Queen on her own colour?

Each player has a white square on their near right corner. The queen goes on the square of her own color; as a result, the kings and queens face each other.

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


What are any USCF tournament rule changes since 1990? I have not played competitive chess since 1990 and I plan to start playing tournaments again. Are there any rule changes I need to know about?

The biggest thing that caught me was the new clock "delay" style. I had to buy a new clock to be able to use mine in a tournament, after taking a break from 2000 to 2010. My old, somewhat expensive digital clock only had "Bronstein", where you add time each move. The newer digital clocks all support the "delay" setting, where you can delay starting the timer each move until a certain number of seconds in. In standard USCF tournaments, they now require a 5 second delay. (I'm not sure when it was implemented, but I assume sometime between 2000 and 2010).

Aside from that, there was something about allowing the new electronic pocket devices for taking down moves. This has caused some controversy, because some of the devices can run chess engines, and can be used for cheating, so TDs and players alike should be careful to note how they are being used. I personally prefer paper.

There is also an entirely new method of calculating ratings, so forget what you knew from back then. (This isn't really a rule.)

Sorry if this isn't comprehensive, but hopefully it is useful.


What would you suggest I play vs. the Ruy Lopez, if I already play the Two Knights Defense vs. 3. Bc4? I play the Two Knighs Defense as Black vs. 1. e4 e5 2. Nf3 Nc6 3. Bc4, in the spirit of counterattack. What would you suggest I play as Black vs. the Ruy Lopez?

There's a simple reason for which 3...a6 and 3...Nf6 are by far the most common replies to the Ruy Lopez: they're the most solid for black. It's very hard to force white into playing something dynamic without comprimising your own position. Of course, you can try something like the Schliemann Defence with 3...f5, though objectively this is dubious for black. However, assuming you aren't playing against titled players, it can still be worth trying if you have good preparation and if you trust that your tactical ability is better than your opponent's. Another option instead of the Schliemann is the so-called "Siesta variation", which features a similar f5 pawn break, though black scores better here than in the Schliemann.

[FEN ""]
1. e4 e5
2. Nf3 Nc6
3. Bb5 a6
4. Ba4 d6
5. c3 f5

This leads to very dynamic play. GM Laurent Fressinet used this in 3 different games at the World Blitz Championship 2017 against other GMs, and won all 3 of them. GM Valeri Yanderimov also has many games in this variation, with mixed results.

Alternatively, if you want something different, you can always try the Cozio defense, both the standard and the deferred variations. This is more solid, though players at lower levels are less likely to be prepared in this opening, and the resulting positions can be surprisingly dynamic with potential pawn storms and black having a strong bishop on g7. The answer to this question provides good insight into the differences between the direct and deferred versions. Of course, the dynamic character of the Cozio depends largely on what white decides to play, and thus you still have to be ready for more quiet or more drawish positions.


Javascript based Chess engine In one of my previous questions I asked about comparison of the strongest chess engines and got a really good answer. While there are little or no doubts that chess engines are stronger than humans, I am curious: Is there any strong javascript implementation of a chess engine that performs well (what is the ELO of the engine)?

Knowing that a lot of high level chess engines are opensource, has anyone made an effort to port something like stockfish or critter to JS?

Stockfish has been ported to Javascript:

https://github.com/exoticorn/stockfish-js


When Lichess analyzes a game, how deep does it analysis? In reference to the request computer analysis feature, how how deep is Stockfish analyzing, such as looking 12 moves ahead?

It tells you at the top right.

The first number (19) tells you the depth it has analyzed to (19 ply = 9.5 moves). Note that because of engine heuristics, it doesn't exhaustively search for every single move 9.5 deep. The second number (23) tells you the max depth to which the engine is searching for. After the bar fills up, there is an optional feature that lets you increase the depth beyond 23 if you want to explore a specific position further.


100 Endgames You Must Know - What's the difference between 3rd & 4th Eds? Does anyone know the difference between the 3rd and 4th edition of "100 Endgames You Must Know"?  I just looked at the Table Of Contents and they are identical and random pages on Amazon look the same too. I would imagine there must be some new use of the new tablebases that were completed since 2012?

De la Villa's "100 Endgames you must know", though apparently a good book seems to have been plagued by an abundance of typos and mistakes as detailed in this blogpost.

So although the culprit in this case has been the 2nd edition, maybe it does make sense to go for the latest edition. Here you can look at the errata page which presumably contains errors that have now been corrected, although as I mentioned some of these corrections probably already happened in the third edition.