What ambiguities remain in the laws of chess? Let an ambiguous rule be defined to be a rule experienced, reasonable, well-informed opponents

are unsure how to interpret in a circumstance (however unlikely the circumstance may be) that can legally arise during play, or
are sure how to interpret, except that each opponent interprets the rule oppositely.

Answers to earlier questions (here and here) have found the FIDE's 50-move rule to remain ambiguous according to the foregoing definition. I do not say that the rule remains ambiguous according to alternate definitions of ambiguity, but according to the foregoing definition I ask: is the 50-move rule the sole remaining such plausible ambiguity in the FIDE's laws of chess, or are there others?

If there are others, what are they, please?

FACTS VERSUS OPINION

To clarify, I do not seek opinions, but seek rather insights and facts. Players indeed have opinions or my question would not exist, but I do not ask what those opinions are. Rather, I ask the fact-based question of which rules have found (or can find) themselves to be objects of opposite interpretation.

I do not ask which interpretation is right.

This is purely academical, but there is an ambiguity whether the position after 1.Nf3 Nf6 2.Ng1 Ng8 is the same as the position at the beginning of the game.

Indeed, article 9.2.2 of the laws of chess states that:

  Positions are considered the same if and only if the same player has the move, pieces of the same kind and colour occupy the same squares and the possible moves of all the pieces of both players are the same.

Indeed, the second and third requirements are met. The problem is with the first one. After 1.Nf3 Nf6 2.Ng1 Ng8 there is no doubt that white "has the move" since her opponent's move has just been made, and law 1.3 defines "having the move" as:

  A player is said to ‘have the move’ when his opponent’s move has been ‘made’.

But who "has the move" in the starting position ? If we follow textually the rules of chess and the definition above, noone "has the move" in the starting position, since noone's opponent's move has been made.

Law 1.2 just says:

  The player with the light-coloured pieces (White) makes the first move

This confirms that the possibilities after 1.Nf3 Nf6 2.Ng1 Ng8 are exactly the same as in the starting position, but doesn't define "having the move" in the starting position. So, can we say that the two positions are identical in respect to article 9.2.2 ?

Well, that's where the ambiguity lies.

Obviously, this problem can only be relevant if someone claims for a threefold repetition when reaching a position 'identical' to the starting position. Which shouldn't happen too often. And such a claim might be denied anyway for lack of affrontment. So I suppose this should not prevent us to play chess with a free mind.


How can I convert a possible pieces' moves to an actual move in a bitboard? If I have a bitboard (e.g. for knight squares he can move to) like this:
00000000
00000000
00000000
00000000
00000000
01000000
00100000
N0000000

How can I "convert" it into a move or "apply" that move?

There are actually two questions in your post

How to convert Attacks in Bitboards to a list of moves?

How to represent those moves?

How to represent those moves?

This question has been discussed here and here thoroughly. But to provide some context to the readers of this post, a very simple way to do this can be to use a class / struct to represent a move

From ( where the moving piece was )
To   ( where the moving piece will be )
Special Move Flag  ( whether the move was a special move, i.e enpassant, casting, promotion)
Promoted Piece ( if the move was a promotion move, what piece did it promote to )

You can also have extra attributes such as captured piece, type of castle etc. But that information can also be deduced using the From and To squares.
So considering the above, we can represent the move as follows
struct Move {
    char from;
    char to;
    char spMoveFlag;
    char promotedPiece;
};

However, a lot of chess engines, including mine use another method that can compress the move into just 16 bits. Read more about that here.
Once we know what a move is, we can answer the next question

How to convert Attacks in Bitboards to a list of moves?

Let's consider that we have a knight on the square d4. We also have a function that returns the attacks of a knight given the square.
. . . . . . . .
. . . . . . . .
. . 1 . 1 . . .
. 1 . . . 1 . .
. . . n . . . .   =  knightattacks(SQ_D4)
. 1 . . . 1 . .
. . 1 . 1 . . .
. . . . . . . .

So let's store this inside a variable knightAttacks
uint64_t knightAttacks = getKnightAttacksBB(SQ_D4);

If you notice carefully we already have 1 of the 4 attributes we need to represent the move, which is the From square - D4. Now all we need to do is somehow get the To square to complete this since a knight cannot perform any kind of special moves.
A very common method is to pop the least significant bit until your knightAttacks is left with nothing i.e 0.
0000011100001000
            ^
            Least significant bit (lsb)

You can follow the link I provided to know how you can perform this, or there is a chance that your compiler might already provide you with it.
You simply need to create a function that clears the lsb of a bitboard and returns its index. Let's call it poplsb().
Altogether, your code can look like this
int from = SQ_D4;
uint16_t knightAttacks = getknightAttacks(from);

while (knightAttacks)  {
     int to = poplsb(knightAttacks);
     MyMoveList.Add( NewMove(from, to, 0, 0) ); // The last two 0's denote that there is no special move
}

This works because each time you pop the lsb, a bit gets cleared until the number is == 0. That's when the loop stops and you have a perfectly good list of moves. The same idea applies to any kind of moves you have created using Bitboards.


Are isolated passed pawns good or bad? I frequently face situations in the late middle game (perhaps only a one minor piece and a rook or two on each side, no queens) where I can force a position (via exchanges) where both players are materially equal but I have an isolated passed pawn on the 4th or 5th rank. I have heard that isolated pawns are bad (because they cannot be supported by other pawns) but also that passed pawns are good. Are isolated passed pawns generally good or bad? Is it good to create them?

I realize the answer probably depends on the position, so guidelines for determining when such pawns are good or bad would make for a great answer.

I'm happy when I have a passed pawn, and my opponent has none. Yet, connected passed pawns are much better than isolated passed pawns.

Here are the raw advantages of a passed pawn:

A passed pawn can no more be exchanged against a pawn, so if it gets exchanged, it will be against something bigger.
If a passed pawn is defended by a non-passed pawn, and the opponent decides to exchange a minor piece against your passed pawn, the defending pawn becomes a passed pawn in turn, keeping your passed pawn advantage, in addition to gaining material. It makes it a little more difficult for the opponent to actually do this.

Still, there are caveats with regards to an isolated passed pawn:

Since your passed pawn can't be defended by another pawn, you'll have to mobilize something bigger to defend it. (leaving less material to act on the issues of the rest of the board)

But:

If you can have a rook defending your passed pawn from behind, you have one less rook on the rest of the board, but you can easily threaten to gain material by appropriately pushing your pawn.
If your opponent decides to block your pawn with a piece, to prevent you from pushing, well, that's one less opposite piece playing on the rest of the board.
If your opponent decides to exchange your pawn, you end up with a rook on an open file.

In the endgame, connected passed pawns beat the opposite king:

If they are side-by-side, they setup a wall of 4 controlled squares, so can't be threatened by the opposite king.

[fen "8/4k3/8/3PP3/8/8/8/8 w - - 0 1"]
If they are connected,  one row apart, the king has to capture the rear pawn first, effectively leaving the front pawn's promotion square.

All these are limited to what the specifics of every position allow.


If a pawn is promoted to queen beside the king is the king instantly in check? If a pawn is promoted to queen adjacent to the enemy king, is the king instantly in check?

Per FIDE Chess Laws, rule 3.1, a piece is said to attack an opponent’s piece if the player’s piece can make a capture on that square (and in one more special case not relevant here).  In full:

It is not permitted to move a piece to a square occupied by a piece of the same colour. If a piece moves to a square occupied by an opponent’s piece the latter is captured and removed from the chessboard as part of the same move. A piece is said to attack an opponent’s piece if the piece could make a capture on that square according to Articles 3.2 to 3.8.
A piece is considered to attack a square even if this piece is constrained from moving to that square because it would then leave or place the king of its own colour under attack.

Per rule 3.9, the king is in check when it is attacked by one or more of the opponent’s pieces.
Therefore, as soon as the move is completed, the king is in check.


Play Colle system as black? I'm fascinated by the Colle system, but I'm not sure if it's applicable when you play as black.  Does anyone have experience in this?

Playing against 1.d4 a similar pawn structure to the Colle, but with reversed colors for black, leads to a defense known as the semi-Slav:

      [FEN ""]
      [Title "The semi-Slav"]
      1. d4 d5 2. c4 c6 {The Slav defense to the Queen's gambit.} 3. Nf3 Nf6 4. Nc3 e6 {The semi-Slav defense to the Queen's gambit.}

The main characteristic of said structure are the pawns on c6, d5 and e6, mirroring the ones on c3, d4 and e3 that characterize the Colle-like systems. The standard development for black also follows the general guidelines that are common in the Colle, that is, Bd6, 0-0 (although in some variations this move is delayed), Ngd7 and e4 when allowed.

This defense is a very well respected one, and it has been used as a drawing weapon by Viswanathan Anand many times. It has the drawback of needing a huge amount of theory in order to not fall behind in development and getting a passive position out of the opening. Players willing to play this need to have patience and accept playing in an somewhat inferior position for many moves before equalizing, and only then looking for an advantage.


Is the result in mini-chess known with perfect play? I do not know, if "mini-chess" is the official name of the game I am talking about.
In mini-chess, the players only start with the pawns (In particular, there are no kings!)

The players play the moves alternate, as in the usual chess.

If a player manages to get a pawn to the opponent's back rank, he immediately wins.

If a player cannot move, he loses.

En passant is like in the usual chess.
Is it known which player wins with perfect play ?

The game is also known under the name pawns-only chess. There is a variation of this game called breakthrough that has more strategical depth by allowing the pawns to also move diagonally.

Since I had already implemented breakthrough, it was very straightforward to add an implementation of pawns-only chess to my Stockfish fork for fairy chess variants (actually I only had to define the rules in a simple structure, see the commit). I have run a single-threaded search for ~10 hours using 2GB of RAM, which yielded a mate score for all first moves, so the results should be reliable, although they are no strict mathematical proof, because Stockfish does forward pruning in its tree search.

The results of Stockfish's search state that the moves 1.b4, 1.c4, 1.f4, and 1.g4 are winning for white, whereas all other first moves are a win for black with perfect play. See the input and output below for details. Since the search was single-threaded and depth-limited, the results should be reproducible.

While writing this answer, I found that someone else independently had obtained the same results, see his chess stackexchange answer and github repository.

input:

setoption name hash value 2048
setoption name multipv value 16
setoption name UCI_Variant value pawnsonly
position startpos
go depth 40

output (truncated):

info depth 40 seldepth 38 multipv 1 score mate 18 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv b2b4 g7g5 c2c4 f7f5 d2d4 g5g4 e2e3 g4g3 f2g3 e7e6 g3g4 f5g4 e3e4 d7d6 d4d5 e6d5 e4d5 h7h6 a2a4 g4g3 h2g3 h6h5 b4b5 b7b6 g3g4 h5h4 g4g5 h4h3 g2h3 a7a5 b5a6 c7c6 a6a7 c6d5 a7a8
info depth 40 seldepth 36 multipv 2 score mate 18 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv g2g4 b7b5 f2f4 b5b4 e2e4 c7c5 d2d3 h7h6 a2a4 b4a3 b2a3 g7g6 h2h4 f7f6 f4f5 g6g5 h4h5 a7a6 c2c3 e7e5 f5e6 d7e6 d3d4 c5d4 c3d4 f6f5 e4f5 e6f5 g4f5 g5g4 f5f6 a6a5 f6f7 g4g3 f7f8
info depth 40 seldepth 40 multipv 3 score mate 20 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv f2f4 c7c5 e2e4 h7h5 c2c4 d7d6 g2g3 g7g6 f4f5 a7a6 a2a3 b7b5 b2b3 g6f5 e4f5 e7e6 c4b5 a6b5 f5e6 f7e6 h2h3 d6d5 g3g4 c5c4 b3c4 h5g4 h3g4 b5b4 a3b4 d5c4 g4g5 c4c3 d2c3 e6e5 g5g6 e5e4 g6g7 e4e3 g7g8
info depth 40 seldepth 40 multipv 4 score mate 20 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv c2c4 f7f5 d2d4 a7a5 f2f4 e7e6 b2b3 b7b6 c4c5 b6c5 d4c5 h7h6 h2h3 g7g5 g2g3 d7d6 c5d6 c7d6 f4g5 h6g5 a2a3 e6e5 b3b4 a5b4 a3b4 f5f4 g3f4 g5g4 h3g4 e5f4 b4b5 f4f3 e2f3 d6d5 b5b6 d5d4 b6b7 d4d3 b7b8
info depth 40 seldepth 39 multipv 5 score mate -19 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv b2b3 c7c5 c2c4 g7g5 a2a3 f7f5 b3b4 d7d6 h2h3 f5f4 g2g4 f4g3 f2g3 h7h5 g3g4 h5g4 h3g4 e7e6 e2e4 c5b4 a3b4 e6e5 d2d3 a7a6 c4c5 d6c5 b4c5 a6a5 c5c6 b7c6 d3d4 e5d4 e4e5 d4d3 e5e6 d3d2 e6e7 d2d1
info depth 40 seldepth 37 multipv 6 score mate -18 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv e2e3 b7b5 g2g4 e7e5 f2f4 e5f4 e3f4 c7c5 f4f5 d7d6 a2a3 d6d5 b2b3 h7h6 a3a4 b5b4 a4a5 a7a6 h2h3 g7g6 f5g6 f7g6 h3h4 c5c4 g4g5 h6h5 b3c4 d5c4 d2d3 c4d3 c2d3 b4b3 d3d4 b3b2 d4d5 b2b1
info depth 40 seldepth 37 multipv 7 score mate -18 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv a2a4 g7g5 f2f3 c7c5 a4a5 d7d5 e2e4 d5d4 e4e5 h7h5 g2g3 g5g4 f3f4 e7e6 f4f5 e6f5 d2d3 b7b5 a5b6 a7b6 c2c4 d4c3 b2c3 b6b5 d3d4 c5d4 c3d4 b5b4 e5e6 f7e6 d4d5 b4b3 d5e6 b3b2 h2h3 b2b1
info depth 40 seldepth 37 multipv 8 score mate -18 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv d2d3 g7g5 d3d4 b7b5 d4d5 a7a5 e2e3 h7h5 f2f4 g5f4 e3f4 h5h4 c2c3 a5a4 b2b3 a4b3 a2b3 e7e6 c3c4 b5b4 g2g4 h4g3 h2g3 f7f5 c4c5 e6d5 g3g4 f5g4 c5c6 d7c6 f4f5 g4g3 f5f6 g3g2 f6f7 g2g1
info depth 40 seldepth 37 multipv 9 score mate -18 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv h2h4 b7b5 g2g4 c7c5 c2c3 e7e5 f2f3 d7d6 d2d3 d6d5 e2e3 c5c4 d3d4 e5d4 e3d4 f7f5 g4f5 h7h5 f3f4 a7a6 b2b4 c4b3 a2b3 a6a5 f5f6 g7f6 c3c4 d5c4 b3c4 b5c4 f4f5 c4c3 d4d5 c3c2 d5d6 c2c1
info depth 40 seldepth 37 multipv 10 score mate -18 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv f2f3 g7g5 c2c4 f7f5 e2e3 e7e5 b2b4 f5f4 e3f4 e5f4 c4c5 d7d6 d2d4 d6c5 d4c5 c7c6 a2a3 a7a6 a3a4 h7h6 g2g4 f4g3 h2g3 h6h5 b4b5 h5h4 g3h4 g5h4 b5a6 b7a6 f3f4 h4h3 f4f5 h3h2 a4a5 h2h1
info depth 40 seldepth 37 multipv 11 score mate -18 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv g2g3 g7g5 g3g4 c7c5 a2a4 d7d5 a4a5 e7e6 b2b3 e6e5 c2c3 e5e4 d2d3 e4d3 e2d3 d5d4 c3d4 c5d4 b3b4 a7a6 h2h3 f7f6 f2f3 h7h6 b4b5 a6b5 h3h4 g5h4 a5a6 b7a6 f3f4 h4h3 f4f5 h3h2 g4g5 h6g5
info depth 40 seldepth 39 multipv 12 score mate -18 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv h2h3 b7b5 h3h4 f7f5 a2a3 c7c5 b2b3 d7d5 c2c3 c5c4 b3c4 d5c4 h4h5 e7e5 d2d3 c4d3 e2d3 a7a5 g2g3 a5a4 f2f3 h7h6 g3g4 f5f4 g4g5 h6g5 h5h6 g7h6 d3d4 e5e4 f3e4 f4f3 d4d5 f3f2 e4e5 f2f1
info depth 40 seldepth 37 multipv 13 score mate -18 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv d2d4 b7b5 h2h3 g7g5 e2e3 h7h5 e3e4 f7f6 d4d5 a7a5 c2c3 h5h4 b2b3 b5b4 c3c4 c7c6 d5c6 d7c6 c4c5 e7e6 g2g4 h4g3 f2g3 f6f5 e4f5 e6f5 h3h4 g5h4 g3h4 f5f4 h4h5 f4f3 h5h6 f3f2 a2a4 f2f1
info depth 40 seldepth 35 multipv 14 score mate -17 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv e2e4 g7g5 d2d4 b7b5 f2f3 h7h5 c2c3 f7f6 b2b3 e7e6 d4d5 e6d5 e4d5 f6f5 g2g3 g5g4 f3f4 a7a5 a2a3 a5a4 d5d6 c7d6 b3a4 b5a4 c3c4 d6d5 c4c5 d5d4 c5c6 d7c6 h2h3 g4h3 g3g4 h5g4
info depth 40 seldepth 35 multipv 15 score mate -17 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv c2c3 b7b5 e2e4 g7g5 d2d4 a7a5 f2f3 c7c6 g2g3 d7d6 d4d5 c6d5 e4d5 e7e6 h2h4 g5h4 d5e6 f7e6 g3h4 h7h5 b2b3 b5b4 c3b4 a5b4 f3f4 d6d5 f4f5 e6f5 a2a3 b4a3 b3b4 a3a2 b4b5 a2a1
info depth 40 seldepth 35 multipv 16 score mate -17 nodes 52290435219 nps 1359031 hashfull 1000 tbhits 0 time 38476253 pv a2a3 b7b5 e2e4 g7g5 d2d3 a7a5 d3d4 h7h5 f2f3 f7f6 e4e5 f6e5 d4e5 a5a4 g2g3 e7e6 h2h3 h5h4 g3h4 g5h4 b2b4 a4b3 c2b3 c7c5 a3a4 b5a4 b3a4 c5c4 a4a5 c4c3 a5a6 c3c2 f3f4 c2c1


Do Barry attack and 150 attack really work that well with Colle-Zukertort? As I was looking for advice on Colle-Zukertort as described here, I found additional info about 2 other attacks that can be used to improve my repertoire pretty efficiently. Here is the information I found:

Colle-Zukertort and Barry attack combined should provide a working repertoire for about 85% of my games played.
Colle-Zukertort, Barry attack and 150 attack combined should provide a working repertoire for about 90% of my games played.

What are your thoughts on this? I'm surprised that having only these 3 tricks in hand seems so effective?

There is a book which recommended this repertoire, A Killer Chess Opening Repertoire by Summerscale.  I used those lines myself when I was in the 1400 to 1800 range, but had to give them up as they were holding back my development as a player.

As a beginner, frankly you shouldn't be worrying about it.  Choosing a repertoire should be near the bottom of your list of 'areas to improve.'  How many games have you won/lost because of familiarity with the opening?  If anything, try to play good, normal, open lines, like 1.e4 e5, and just focus on the chess.  You'll get more out of that than by studying the nuances of the Barry Attack.


Catalan opening - plans for white after exchanging on d5 From theory I've encountered on the Catalan, I've understood that when black goes b7-b6 before first playing c7-c6, a good plan for white is to capture on d5. WI've understood that the rational for this might be that after black signaling that they might fianchetto, there's no longer a reason to keep not allow the exchange of the black e pawn, as their light squared bishop is anyway coming out, and that it's better for white that black recaptures with the e pawn than the c pawn (I'm guessing as after black later pushes the c pawn the hanging d- and c pawns might that become weak). However, I find it difficult to then come up with a follow up plan. What more breaks are there for white? Usually, when I still have my c pawn, I go for the e2-e4 break, but that seems less attractive in a case when there's no c pawn and I'd be landed with a isolated d pawn. Thoughts?

    [FEN "rnbq1rk1/p1p2ppp/1p2pn2/3p4/2PP4/5NP1/PP1NPPBP/R2QK2R w KQ - 0 8"]
1. Nf3 d5 2. d4 Nf6 3. c4 e6 4. g3 Bb4+ 5. Bd2 Bxd2+ 6. Nbxd2 O-O 7. Bg2 b6 *

The idea of exchanging on d5 when Black goes for an early ...b6 is usually connected with play on the c-file: Nc3, Bf4, Rc1, maybe Qa4.

In this particular position, after ...Bxd2 Nbxd2, this plan is not available and the pawn exchange is much less promising. Here, you can stand with the main plan of preparing e2-e4 (with 0-0, Qc2, Rd1), or look for an opportunity to exploit the dark squares (Ne5, e3, and someday either f4, Ndf3 or c4-c5).

If memory serves, 6.Qxd2 is a bit more promising than 6.Nbxd2 in this line.


What does ELO stand for? What does the acronym ELO stand for in the context of chess, as in the ELO rating system?

It doesn't stand for anything at all, because it's not an acronym. It should be "Elo" rather than "ELO." The Elo rating system is named after the Hungarian-American physics professor (and 8-time state champion chess master) Arpad Elo, who originally devised his rating system around 1960.


Unable to confirm theoretical evaluation Theory claims equality for Black in the below diagram.
My engine claims White is better and demolishes the line with convincing moves.
Since I have old laptop, with 2GHz dual core CPU, I was wondering if someone with stronger engine can analyze the below position for me (hopefully they will be able to prove my engine wrong).
[StartFlipped "0"]
[Title "Black to move"]
[fen "rn2kb1r/pp3ppp/2p1pnb1/q3N3/2BP2PP/2N5/PPP2P2/R1BQK2R b KQkq - 0 9"]

For a Computer, White is Better.  For a Human, it's unclear.
White has quite a few advantages here - notably more space and superior development.  Black has one major advantage, though.  White's king is exposed and shall remain so for quite some time.
Computers excel at positions in which perfect defensive play is required - that is, positions such as White has here.  A computer will almost certainly see and defuse the various tactical threats to the White king, and eventually the computer should be able to convert the many advantages White has into something concrete.  But a human playing White is quite likely to err and allow Black the chance to make an effective attack.  Some humans will prefer to take on the Black pieces, on the premise that if they play aggressively White will eventually slip.  Other humans will prefer White.  Thus, we say that the position is "unclear".


Why doesn't castling reset the 50 moves rule? Capturing a piece or moving a pawn irreversibly changes the state of the game and thus resets the counter for the 50-move rule. Since castling irreversible changes the state of the game too, it seems to me that it should reset the move counter too, but it does not. Why is that?

I don't know the reason, but I can make a guess.

In standard algebraic notation, it's fairly easy to look at a scoresheet and see whether a capture has been made or a pawn moved.  Captures have an "x" in them, and pawn moves don't have a piece listed. But if loss of castling rights also triggered the 50 move rule, you'd have to look at the rest of the game (instead of just the last 50 moves) to see whether castling rights had previously been lost. This would seem to increase the burden on arbiters.

Also, it's rather unusual for this to matter. Most people are going to move their king (and/or both rooks) before they reach a point in the game where the 50 move rule would begin to apply.


What does double-check mean in four-player chess on chess.com? The rule says:
Delivering a double-check is worth +5, and triple-checks are worth +15

Is a double check when I am

checking two players at one move
checking one player with a normal double check
checking a player that is already under check

Counting that there is a "triple check" either the rule one or three should be true because you can not give a triple check to one player by only your move. However, I am not sure if there are points for the normal double-check.

Double Check in 4 man chess basically means  checking  two kings in one move.
Same goes for triple check.

PS. It's not worth the points so don't go for it unless you win because of it.


Why is this a missed win? I found myself in this position as Black. I played Kb6, but the engine on chess.com suggested that the move Kb7  is a missed win, and the continuation below would have been winning for me. It gave no lines beyond what is below, and I can't see how this is a win for Black. Is this a fault with the engine, or is there some line that I've completely missed?

[Title "Unexplained"]
[FEN "2b2r2/2p5/p1kb2qp/1p1p4/3P4/7P/PP1BQPP1/RNR3K1 b - - 0 1"]

1...Kb7 2.Qe3 Rg8

In response to comments questioning if I have the position wrong or missed a root, I confirm I was a full rook down and felt this was a completely lost position. I have now included a screenshot demonstrating the strange opinion of the engine at chess.com

I guess it's a bug with the engine then?

This is not a missed win for black, both Kb6 and Kb7 are equally losing for black as you are simply a full rook down without any real compensation. Qe3 move simply stops black's only way to breakthrough as it stops Bxh3. That is not white's only move either, Kh1 and Rc3 (though walks in the way of the knight) are sufficiently good for white too.

So either:

The cloud engine didn't get to run sufficiently long and gave a wrong evaluation, or
you simply mis-read or mis-interpreted the evaluation of the engine, or
you're showing us the wrong position here.


Why not Ng4 in Sicilian after Nf3? After

[FEN ""]

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nd4 Nf6 5. Nc3 a6 6. Be3 e5 7. Nf3

(which is trendy at top level in 2017) I am wondering why Black doesn't play 7...Ng4.   I only found a couple old games with 7...Ng4, and both ended in a draw.

6...Ng4 doesn't look good at all.

Tactical flaw:

Black is behind in development, so White should aim for direct play with 7.Bg5 and then:

7...f6 8.Bc1 [8.Bh4] Be6 9.h3 Nh6 10.Bxh6 gh6 11.Nh4 [11.Be2] and Black has huge weaknesses on the light squares.
7...Be7 8.Bxe7 Qxe7 9.Nd5 [9.Qd2, 9.Bc4] Qd8 10.Bc4 with a nice bind is probably the lesser evil for Black.
7...Qb6 8.Qd2 [or 8.Bh4 Qxb2? 9.Nd5 and Black cannot block Nc7+] Qxb2 is too greedy: 9.Rb1 Qa3 10.Nd5 Qc5 11.h3, or 11.Be3 and 12.Nb6 winning material, or 11.Rb3 with a huge attack.

Strategic reason:

It the structure with a hole on d5, the fight for the white square is essential and probably more important than the bishop pair. White often plays Bg5xf6 in Boleslavsky, Najdorf and Svechnikov variations. Thus trading the knight for the Be3 is not a big achievement, especiallly at the cost of two tempi, even if White plays the simple 7.Qd2 Nxe3 8.Qxe3 Be6 9.0-0-0 or 9.Ng5.


Was Wolfgang Unzicker the last Amateur GM? Wolfgang Unzicker was a German GM, rated about 2550 and worked as a judge. In the sense of holding down a job while playing, he was an "amateur" player.

So was Unzicker, a GM in the 70's, the last amateur GM?

So in the sense of holding down a job while playing he was an
  "amateur" player.

  So was Unzicker, a GM in the 70's, the last amateur GM?

No. Here are 4 current British "amateur" grandmasters.

English GM Matthew Turner is a teacher at Millfield School in Somerset.
English GM Matthew Sadler is a computer consultant in the Netherlands.
English GM Luke McShane (currently on 4/7 in the Netanya Masters) is a financial trader in London
Scottish GM Dr. Jonathan Rowson is Director of the Social Brain Centre at the Royal Society of Arts in London


Where can I find the saved games or PGN files in the Play Magnus app? I have completed games on the Play Magnus app and clicked on the option "Export game as PGN file " but I don't know where to find those saved games.

Unfortuately, the Play Magnus app is not capable of creating PGN files. So, when you click on "Export game as PGN file", the game is copied to clipboard. You can then paste the game in a text editor and save it as a PGN file.


Is there published advice on giving simuls? I unexpectedly found myself giving a tiny simul recently.  I won all the games, but it left me wondering if there is any published advice on how to handle simuls as the single player.  (There is plenty of advice on how to try to beat the single player, but that's a different story!)

There are several techniques that a lot of masters commonly use in simuls.

(1) Know the players. Lower rated players can be confused easily with unsound play/attacks, leading to quick wins. You will also know which players to watch out for and spend more time on. Kasparov was very ardent on this point, and was very upset that a 2200 player posed as a 1600 once to get into his simul.

(2) Avoid heavy tactical complications against the stronger players. Simul players use intuition heavily to find good moves quickly. This is not possible in complicated positions, where a lot of time needs to be taken to calculate many lines. This is where the simul master has the most trouble. Generally, steer the game to quieter play, or make sure to only enter complications that clearly favor you. As a corollary of (1) and (2), you should try to defeat the weaker players quickly.

(3) Offer a few early draws. In games where you might not want to play on (games that are more tactical, against stronger players, worse position, etc.) you can offer a draw to reduce the games you play, and focus on doing better on the other games.

These are a few standard tactics that many simul masters use.


Is chess.stackexchange.com a good site for someone learning how to play chess? Would you say this is a good website for someone learning how to play chess?
Hello again, I'm trying to teach myself how to play chess, Im a mature adult, I caught on quickly.

No, it's not, but it might still be very beneficial to you. (Chess) Stack Exchange is a question and answer site, so:

  You should only ask practical, answerable questions based on actual problems that you face.

(taken from here).

So don't expect any tutorials here, or the possibility to play an actual game against someone. However, browsing through the site you will find a lot of resources which might help you - this question for example. If you need a resource on a specific topic, and nobody has asked it before, please go ahead and ask for it.


Does the first-move advantage for White have real meaning apart from the highest levels of play? Most games that involve taking turns, with one player going first by lot or agreement, have some sort of advantage to going first. Tic-tac-toe, for instance, is a guaranteed draw for player 1, assuming correct play. Connect 4 is a guaranteed win for player 1, assuming correct play. The first move in Go is considered so powerful that player 2 receives a bonus of 5.5-7.5 points. The first-move advantage in Chess is less obvious, although statistically speaking White has an advantage of ~52-56%.

White's advantage is essentially that of time. He can count on starting ahead of Black and in theory should not go behind except by choice. He can even attempt to trade material for time.

Black's advantage is that of choice, or response. She can let White develop the game as he chooses, or she can force the game into a different line of play altogether. Presumably she knows her purpose in playing her responses to White, and can take advantage of White's loss of choice.

This being said, does it have meaning outside the highest levels of play? Is the game theoretically close enough that there isn't a way to equalize it 100%? (Related previous discussion suggests that the first move is "worth 25-45 rating points". However, the question didn't directly deal with the first-move advantage, instead referring to it tangentially in a discussion of handicaps.)

I think any real answer to your question will have to be statistical in nature.  There's rationale behind the advantages and disadvantages of having the first move, but really, we'd be mostly guessing regarding how important these factors are.

With that in mind, I quickly ran some code to check what patterns I could pick up through the million base PGN library (check below for disclaimer / methodology):

ELO                  %W      %D      %B
1700: 56    games:  37.50 / 33.93 / 28.57
1800: 192   games:  34.38 / 35.42 / 30.21
1900: 736   games:  37.23 / 34.24 / 28.53
2000: 4682  games:  36.27 / 32.14 / 31.59
2100: 10568 games:  36.56 / 34.79 / 28.64
2200: 23486 games:  34.42 / 38.11 / 27.47
2300: 33444 games:  31.25 / 45.06 / 23.69
2400: 49706 games:  28.53 / 51.73 / 19.74
2500: 40264 games:  26.38 / 57.28 / 16.33
2600: 16946 games:  27.88 / 56.14 / 15.97
2700: 3581  games:  28.43 / 56.07 / 15.50
2800: 68    games:  27.94 / 55.88 / 16.18

As you can see, at the highest levels (around 2500 and above), the majority of games are draws (around 55%), and from the remainder, wins by White outnumber wins by Black with a ratio of around 1.75:1.  A very significant advantage, indeed.

The ratio drops rapidly at lower levels, and by the time we are around 2000 in rating, it's closer to 1.2:1.  From here, it doesn't seem to change much, and I don't really have data for under 1700 rating.  Of equal importance is the percentage of drawn games - along with the White / Black win ratio, the number of draws drops significantly.  I would interpret this data along the following lines (although I'm reading a bit into the data here):

White does have a tangible advantage, but needs to play very accurately to capitalise on it.  At the "lower levels", tactics (and thus mistakes) play a far larger role, almost drowning out the underlying small advantage.  It is still noticeable, however, even at the 1700 rating level, and with a small sample size.  So, to answer your question: yes, the choice of colour is relevant even at lower levels, although much less so than at GM level.

Disclaimers and whatnot - I ran through the million base PGN library (+- 1.7 million games), and simply discarded any games with a greater than 50 rating points difference between the players, in order to select only games between similar strength players.  Statistically, this shouldn't make all that much difference (the "unfair" games should have each other balanced out, given sufficient numbers), but there are a number of exhibition and simul games in that library which I was attempting to exclude from the data set.  In any case, this is not meant to be strictly scientifically correct; it's just the results of a few minutes of programming.


What kind of training should a Class B do for a year, if he or she wants to defeat a 2100 player? There's an Expert Class that I specifically want to have a good game with or defeat. Though I always get destroyed badly in blitz. What can a Class B do in year to become strong enough to have a really good game or even defeat an Expert Class? Any advice?

If you want to defeat specifically one opponent the easiest way would be to check his games, try to find his weaknesses, and try to prepare and then reach positions which he doesn't feel comfortable with. Maybe this will be simple positions maybe closed games with manovering, maybe sharp tactical games. See what type of positions he tries to reach, and drag him to completely different ones. Obviously you should invest most of the time to get better in this kind of positions.

If in general you want to have a fighting chance against an expert player, without investing the time and energy to get good enough, than you should do lot's and lot's of combinations, prepare an opening repertoire with gambit openings, and try to catch him in a dobious, but complicated position. You will lose more than win, but every now and then you will nail him.

And then there is the hard but revarding way of generally perfecting your game :).


Chess game viewer plugin for wordpress Do you know of any PGN/game viewer for Wordpress, which can be used to generate diagrams, and chess games?

There are a couple.  The most popular is likely Embed Chessboard.  The nice thing about it is that the tags are simply PGN references:

  [pgn parameter=value ...]
  ... chess games in PGN format ...
  [/pgn]

So if you're already familiar with PGN, put it into your Wordpress page and the plugin detects it..

Would you share your Wordpress site URL in comments once complete?


What am I supposed to learn from this puzzle? I'm still in the learning stage of playing chess, and was a bit frustrated by this puzzle.
https://www.chess.com/puzzles/problem/683680
After my initial attempt failed I tried all the moves I could think of to succeed (I usually do this and often get the solution on my second or third try) I used the hint feature to get the solution. None of this would be at all shocking to me, but the puzzle is rated at 715 and my failed attempt cost me 14 rating points.
Looking at the analysis board the line played gives only a fractional advantage to white, but any other move would result in a significant decrease in advantage.
So now I know what the correct answer is, I'm wondering if this puzzle is possibly underrated or if I'm missing something in my chess practice so far...
I seem to do a lot of puzzles on Chess.com where a seemingly simple mate-in-3 is rated 1000+ and then puzzles like this one that make me doubt my training so far.
Any thoughts on what I can takeaway from this puzzle, or what I can do to fill this gap in my knowledge so far?

@B.Swan incorrect. Everything is -3 but the line played, +3. The puzzle is meant to help you learn the power of the pin (you trade and then Rc2 is played, so the knight cannot move because of the king behind it and you win a free piece). Even a free pawn can make or break a game; a piece is amazing, and if you can get it, you are likely to win the game. It is hardly a "fractional advantage".


What is the format for USCF's Golden Database? I was wanting to collect some statistics about players, and also just easily update player ratings for my local club. I tried the web crawls on USCF's Member Services Area (even using the thin pages http://msa.uschess.org/thin.php), but it takes too long just waiting for the server to respond. How can I read the players from the Golden Database into a program I have made?

You probably found all of this on your own already, but here is what I've learned:

The "Golden Database" can be downloaded in many formats, one of them as a tab separated text file. If you have made a program already, coding the import of the file should be trivial. Each line consists of:

LASTNAME,FIRSTNAME(S)   USCFID  EXPIRYDATE  STATE   RATING  OTHERRATING

These files have certain limitations.

Only room for 2 ratings, so 2 files is provided with either speed or
blitz rating as the 2nd.
Fields have limited lengths, so long names might be cut off.
Rating numbers can come in many variants, 1234/12 means the rating is
based on 12 games, while I forget what 1122* means. (Provisional?)
Ratings can be texts as well, like 'Unrated' or 'Duplicate', etc.

If not you, then I hope this helps someone else...


Firouzja vs Kovalev: what went wrong for black in the opening? In the first round of the ongoing Wijk aan zee Masters tournament, Firouzja won vs Kovalev. Apparently, right out of the opening white had gained a winning edge. In particular, somewhere around 16...c4 it seems to be where black went somehow wrong (computers also favoring white there). But from the opening point of view,

how can Kovalev's 16...c4 be so bad that white has already a substantial edge? Was this a mix-up in the opening variations? First glance, it seems b5 is indeed weak as c4 frees d4 square for the knight, but can we not hold on to the b5 pawn differently? for example with Qb6?

Position at move 16:

 [title "Firouzja vs Kovalev 16...c4"]
 [fen "r2qrbk1/1b3pp1/p2p1n1p/1p1P4/Pnp1P3/5N1P/1P1N1PP1/RBBQR1K1 w - - 0 17"]

tl;dr: Wrong move order by black in the opening: the c4 advance must be prefaced with Nd7 in the played Zaitsev variation.

That said, and although your hunch about the early c4 is correct, I'm afraid there's no simple answer that immediately explains why the immediate c4 is bad and why Nd7 is so crucial, since the Ruy Lopez and the Zaitsev are highly theoretical openings and thus, all about nuances and concrete assessments.

In any case, here's an attempt to answer it in a simplified manner.

Bit of context first: the game started out as a classical Ruy Lopez which then transitioned into the Zaitsev variation. Then in particular after 11...Bf8, Firouzja opted for the older system with 12.a4 which is
a variation rich in theory dating specially back to the Kasparov-Karpov games (see e.g. 1990 games). Instead of 12.a4, nowadays the more go-to and modern
option is 12.d5. So, seeing 12.a4 might have come as a bit of a surprise.

Fast-forwarding to the key moment of the opening, in the a4 variation white often waits out the d5 advance until black has played c5. Then after 15...c5 16.d5

the main and key move by black is to play Nd7 (diagram below): which concretely prepares either options of c4 or f5:

c4 (left diagram): with ideas of establishing either a knight or a protected advanced pawn on d3
f5 (right diagram): directly undermining the defense of the d5.

However, Kovalev played the immediate c4 advance without the inclusion of Nd7, this was the main inaccuracy! The problem is black's losing a pawn in the all ensuing lines without any dynamic or positional compensation for it. Let's see some of these lines in the annotated diagram below:

 [title "16.c4 without Nd7"]
 [fen ""]
 [StartPly "33"]

 1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 d6 8. c3 O-O 9. h3 Bb7 10. d4 Re8 11. Nbd2 Bf8 12. a4 h6 13. Bc2 exd4 14. cxd4 Nb4 15. Bb1 c5 16. d5 c4 17. Nd4 {b5 pawn is attacked twice now} Nd7 {this is what happened in the game, but Nd7 here is too late} (17...Qb6 {an attempt to directly defend the pawn, but the queen ends up being completely misplaced as we'll see and too far away from the kingside.} 18. N2f3 {defending the d4 knight and preparing Be3} g6 19. Be3 Qc7 {side-stepping the discovery} (19...bxa4 {just for the sake of discussion, let's see how black loses by force if they do not side step the discovered threat and take on a4 instead} 20. Ne6 Qb5 21. Nxf8 Rxf8 22. Qd4 {and white's kingside attack is too much to parry as the king on g8 is defenceless}) 20. axb5 {winning the b5 pawn if black recaptures, so only chance is to take on e4 instead} Nxe4 21. Ne6 {and white's nearly winning already as black's position is collapsing after fxe6 Bxe4. Ne6 is a thematic move in these structures with the pawn on d5.} ) 18. axb5 axb5 19. Rxa8 Bxa8 20. Nxb5 Qb8 21. Na3 {c4 is falling next, as happened in the game} Nd3 22. Re3 Nxc1 23. Qxc1 g6 24. Naxc4 {rest of the game is not included here}

In contrast, here's how the variation usually continues when c4 is prefaced by Nd7:

 [title "Correct move order: Nd7 before c4, actually setting up Nd3"]
 [fen "r2qrbk1/1b3pp1/p2p1n1p/1ppP4/Pn2P3/5N1P/1P1N1PP1/RBBQR1K1 b - - 0 16"]
 [startflipped "0"]

 1...Nd7 {black entertains both options of f5 and c4 after Nd7} 2. Ra3 {These are nuanced moves which were specially polished in Kasparov-Karpov games of 90's. Ra3 is a multi-faceted move, moving the rook to a protected square so that axb5 axb5 lines do not force white to exchange rooks at once, moreover activates the rook along the 3rd row both additional coverage of d3 square and potential rook swings to kingside} c4 3. axb5 axb5 4. Nd4 Rxa3 5. bxa3 Nd3 {black appears to be losing a pawn nonetheless, however as demonstrated by Morozevich among others, black is in fact able to maintain the awkwardly advanced d3 pawn with Nc5 which gives black sufficient dynamic compensation for the pawn} 6. Bxd3 cxd3 7. Re3 Nc5 {and black is well on time with Nc5 as opposed to what transpired in the game where black delayed Nd7 to after c4!} 8. Nxb5 {not white's best choice} (8. Bb2 {white's best choice here is not to take the pawn as that gives black too much counter-play.}) Qa5 9. Nd4 Qc3 {and Qa1 threats are constantly in the air. Additionally, the knight on d2 is bound to the defense of the e4 pawn. Black is clearly better.}

It would go beyond the scope of this post to exhaust all possible sub variations both with and without Nd7, however I hope the above discussion and lines clarify the importance of the inclusion of Nd7 (and the playability of the ensuing lines) in contrast to the inaccurate early c4 without Nd7 as happened in the game.


Engines tuned to masters’s styles I saw a stream by IM Eric Rosen where he showed a stronger version of stockfish than the one on lichess.org. He said that it is a version that is given to masters with the evaluation function specifically  tuned to their playing style.
Does anyone have an idea how this personal tuning is accomplished? I know that stockfish regularly gets tuned, but I believe that is for strength optimization not playing style “fitting”.

There are many elements that a computer looks at to determine how the computer plays.  A more defensive computer would place more value on the pawns around the king.  A more attacking computer would place more value on retaining pieces, to maintain the attacking possibilities.  The choice of opening and the central pawn structure affects the overall playing style.
Galahad chess and Chessmaster had to option to change around two dozen of these evaluation values.  Beowulf read these values from a config file, but they weren't easily modified.


How does lichess rating compare with chess.com rating? I have accounts on both of these websites, but I don't know the difference of how they do the rating. Can anybody tell me at least a difference between lichess and chess.com rating?


Piping Stockfish input I'm trying to write a Linux command line UCI interface for Stockfish. My program writes a bunch of commands to a text file and then tries to pipe them to Stockfish via the command line. My problem is, whenever I try to analyse a position, the program exits almost immediately:

sf.txt:

position startpos moves e2e4
go movetime 5000

output:

~$ stockfish < sf.txt
Stockfish 261014 64 by Tord Romstad, Marco Costalba and Joona Kiiski
info nodes 0 time 2
bestmove a7a6 ponder (none)

As you can see, the program exits in 2 ms instead of waiting for the analysis to finish. Has anyone delt with this issue before? Is there a preferred way of interfacing with Stockfish?

Solution: Use 'expect' script as shown below. Tested with stockfish_8_x64_modern.

  BlindKungFuMaster: "I think the main problem is that the uci protocol is a dialog."
    I agree!

#!/usr/bin/expect

spawn ~/stockfish_8_x64_modern

expect -timeout 1000  Linscott

send "setoption name Ponder  value false \r isready \r"

expect -timeout 1000  readyok

send "setoption name Hash    value 2048 \r isready \r"

expect -timeout 1000  readyok

send "setoption name Threads value 8    \r isready \r"

expect -timeout 1000  readyok

send "setoption name MultiPV value 4    \r isready \r"

expect -timeout 1000  readyok

set row8 "rnbqkbnr"

set row7 "pppppppp"

set row6 "11111111"

set row5 "11111111"

set row4 "11111111"

set row3 "11111111"

set row2 "PPPPPPPP"

set row1 "RNBQKBNR"

send "position fen $row8/$row7/$row6/$row5/$row4/$row3/$row2/$row1 w KQkq - 0 1 moves e2e4 \r isready \r"

expect -timeout 1000  readyok

send "go infinite \r"

expect -timeout 999999  readyok


Why is Byrne vs. Fischer (1956) regarded as the "Game of the Century"? (This is the game in question.) Is it because it was played by a 13-year-old Bobby Fischer?  Would it have been different if it were played by a much older player?  Who labeled it the "game of the century" and did this game between Tal and Smyslov (1959) miss being the "game of the century" by 3 years?

The "Game of the Century" was a term coined by Hans Kmoch in Chess Review. In short it was a bit of sensationalism. While Fischer did show a talent for combinations and an impressive sacrifice, the real importance of the game was the story of a leading chess master vs a phenomenal prodigy about to begin his historic rise.

Still, it's helpful to note what David Levy said: "In my opinion, however, the game, attractive though it is, can in no way be held in such high exaltation. It was merely the fact that the combination was created by a thirteen-old boy that brought the game so much publicity. Had it been played in the Barnet League between two sixty-year-old men it is doubtful whether it would have been considered worthy of publication".

As for the game between Tal and Smyslov, the similarities in age are easy to spot, but the chess playing doesn't really compare.

The full game and commentary can be found over at Wikipedia.


Why is the definition of check not circular? If you want to determine whether a player is in check I think you would:

1.1) determine every legal move of the opposition;

1.2.) determine whether such a move threatens our king (i.e. could 'take' the king)

To determine 1.1) above you need to:

2.1.) consider every active piece of the opposition and its possible moves;

2.2.) see whether that move conforms to a valid type of move (i.e. moves likes a castle,knight etc)

2.3.) confirm that such a move doesn't place the opposition in check (otherwise it's not a valid move)

Yet 2.3 requires us to go back to 1.1-in order to determine whether the opposition's move is not check (and thus valid) we need to consider all the possible moves of our side (the side which we wanted to determine if it was in check originally).

It seems that this leads to some horrible circular dependency. Obviously, it doesn't as otherwise chess wouldn't be a game!

Where am I going wrong?

A move can be illegal because the opponent could "take" the king. This "taking the king" move does not need to be "legal". See Can a piece pinned to my king put the opponent's king in check? and Is the king actually in check if the attacking piece cannot be moved?


Is there still any top grandmaster who still regularly plays Queen's Gambit Accepted? I believe Anand used to play QGA, but it seems like he stopped - presumably after losing several games to Kramnik with it.

Of players who have been inside top ten it is Ponomariov who uses this opening the most often. Ivanchuk plays it too, but then again he plays most anything. And Nakamura played it a few times last year.

You can do searches for free online at 365chess.com.  Here is an example:
http://www.365chess.com/search_result.php?search=1&p=1&m=4&n=109&order=belo&ms=d4.d5.c4.dxc4&rev=&start=50


List of female chess players by peak FIDE rating Update/Request: The answer currently doesn't include countries and other trivia like in the original one. Please consider posting an answer like this or editing current answer to include these. However, I consider the current answer complete even with this update. This update/request is just some additional thing.

There is a Wikipedia list is for all of the top-rated FIDE chess players. But where is the list of female chess players by peak FIDE rating?
I'll start:
1 - Hungary - Judit Polgar - 2735 - 2005-07 -   1976 - N/A

The raw data which could be used to extract this information is available on the FIDE website (from 2001) and the Olimpbase website (before 2001). What you will need to do is clean the data (the older the data the more "dirty" it is), construct a relational database and insert the data. Then you will be able to use SQL to search the database for the data you want.
Having done this, here is a list of the top female players of all time above 2500 appearing in the periodic FIDE rating lists (i.e. not the live list, because that data is not available to us)
FullName    Max Period

Polgar, Judit 2735 7/2005, 10/2005
Hou, Yifan 2686 3/2015, 5/2015
Koneru, Humpy 2623 7/2009
Muzychuk, Anna 2606 7/2012, 8/2012
Ju, Wenjun 2604 3/2017
Goryachkina, Aleksandra 2593 2/2021
Kosintseva, Tatiana 2581 11/2020
Zhao, Xue 2579 9/2013, 10/2013
Polgar, Zsuzsa 2577 1/2005 ->
Kosintseva, Nadezhda 2576 11/2010
Xie, Jun 2574 1/2008 ->
Dzagnidze, Nana 2573 6/2015 - 10/2015
Muzychuk, Mariya 2563 3/2016, 4-6/2019
Kosteniuk, Alexandra 2561 1/2018, 2/2018
Lahno, Kateryna 2560 12/2018 - 2/2019
Galliamova, Alisa 2560 7/1998
Stefanova, Antoaneta 2560 1/2003, 5-7/2010
Chiburdanidze, Maia 2560 1/1988
Cramling, Pia 2550 10/2008
Gunina, Valentina 2548 6-7/2015
Zhu, Chen 2548 1/2008
Lei, Tingjie 2545 3/2018
Harika, Dronavalli 2543 11-12/2016
Cmilyte, Viktorija 2542 6/2017
Sebag, Marie 2537 3/2013
Zatonskih, Anna 2537 5/2011
Khotenashvili, Bela 2531 6/2013
Tan, Zhongyi 2530 3-4/2016
Batsiashvili, Nino 2528 3/2018
Danielian, Elina 2521 7/2011
Ioseliani, Nana 2520 7/1977
Saduakassova, Dinara 2519 1/2020
Xu, Yuhua 2517 4/2006 - 7/2007
Paehtz, Elisabeth 2513 9-10/2018
Wang, Lei 2512 10/2001
Hoang, Thanh Trang 2511 11/2013 - 2/2014
Pogonina, Natalija 2508 7/2014
Kovalevskaya, Ekaterina 2507 7/2001
Zhu, Jiner 2507 10/2019
Arakhamia-Grant, Ketevan 2506 7/2009
Wang, Pin 2506 10/2000
Polgar, Sofia 2505 7/1998
Girya, Olga 2505 9/2017
Socko, Monika 2505 4/2008
Ruan, Lufei 2503 1/2014
Mkrtchian, Lilit 2503 1-3/2010
Matveeva, Svetlana 2502 1/2004
Krush, Irina 2502 10-11/2013
Ushenina, Anna 2502 7/2007
Qin, Kanying 2501 7/2000
Skripchenko, Almira 2501 1-4/2003


Can you identify this game with a mate in 12? I vaguely remember it being from a game played in the USSR ca. 1960.  I'm certain it was from before 1985.

[fen "2k1r2r/ppn3pq/b7/5p2/5Qn1/2N1B1P1/1P3PB1/2RR2K1 w - - 0 1"]

I can't find the actual game neither in my database nor at, say, chessgames.com. However, the position appears as puzzle 210 -- with the apt description "Running around like a squirrel in a cage" -- in the book 1000 Checkmate Combinations by Victor Henkin, and there it is attributed to a game Aleksandrov-Zaitsev 1974.


Why was 49...Rb4+ played in this puzzle? I was looking at the answer of today's puzzle in chessgames and see that the reason I wasn't able to solve it because I missed a key move in the solution:

Black played 49...Rb4+
note: this is not the puzzle position, this was taken from the middle of the puzzle solution.
note2: the board seems to be correctly flipped.

8/7p/1pBP2pk/pP6/K6P/6P1/1rp5/4R3 b - - 1 49

I don't really see the advantage of doing that move, is it something related to winning tempos? If so, how?

Moving the king once like that is a priming move in order for Black to be properly aligned at a crucial point in a few moves.

Without the priming move this happens which allows White to win

8/7p/1pBP2pk/pP6/K6P/6P1/1rp5/4R3 b - - 1 49

1... Rb1 2. d7 Rxe1 3. d8=Q c1=Q 4. Qf8 Kh5 5. Bf3++

So it is desirable to get a check in when promoting in order to win the game:

8/7p/1pBP2pk/pP6/K6P/6P1/1rp5/4R3 b - - 1 49

1... Rb4 2. Ka3 Rb1 3. d7 Rxe1 4. d8=Q c1=Q+ 5. Kb3 Re3+ 6. Qd3 Rxd3+ 7. Ka2 Ra3++

I decided to show a simple mate ending. It is possible for white to prolong the inevitable . This would be done with 3. Be4 . Although it is possible for white to slightly delay, Black still wins with Rb1.


Consistently playing moves below my potential Basically: I make blunders. The most disgusting, reprehensible, indefensible mistakes that I would've discarded had even one neuron in my brain noticed it before I moved. I know everyone experiences them to a greater frequency than they would prefer. But I can say that they are without a doubt the number one deficiency in my play, and also the number one thing detracting from my enjoyment of the game.

I play mostly online, and am around 1900-2000 on lichess after several on-and-off years of chess. Up until recently I have always played with long time controls (~30 minutes with increment), although I have started experimenting with blitz  in an attempt to remedy my tendency to take an unreasonably long time studying certain positions and still making outright blunders; this hasn't helped. Regardless of the time controls, I still always feel myself at an imbalance compared to my opponent because while I may have slightly superior technique that'll allow me to chisel fractions of a pawn of an advantage each move, I am more prone to naked blunders throwing the whole game away in one move (and unless it's blitz, I have little hope of recovering since my opponent can play consistently).

I really don't think this is just in my head. I've tried "slowing down" (even though my calculation/processing style is already very laid back), I've tried "checklisting" for blunders (but the checklisting just becomes a hollow routine that can't even cover all the dynamic ways I can screw up), I've tried just waiting throughout months of playing but I don't feel I'm adapting. I love studying and practicing the more refined aspects of chess, and I feel like I'm capable of it the vast majority of the time, but I'm really only as strong as the weakest link in my performance. Has anybody else that's felt the same as me managed to improve their recurrent blindness?

I don't know that I have any good answers for your question, but I wanted to commiserate with you.  One can learn a new opening variation or master an unfamiliar endgame, but such improvement is only incremental as this new knowledge gets applied only once in a while.

What you are asking for is to improve something that is central to defining your playing strength.  If we could all have perfect tactical vision, we would be as strong as computer engines.

I'm also relatively weak in this area, but recently I was able to go from uscf 2200 to 2300+.  One thing I tried to do was consider additional candidate moves in my thought process to better avoid tactical blunders, but I didn't find that helped much.

What did help though a bit was me focusing on bringing harmony to my pieces and position with every move.  What I mean by this is that I made it a priority to make sure that my pieces protected each other instead of being potentially hanging on a limb unprotected.  As GM John Nunn has said, loose pieces drop off.  If you have harmony in your position among your pieces, then there are many fewer opportunities to blunder material because even if you miss something the tactics will tend to work out in your favor more often.


Stockfish ELO vs search depth Could Stockfish beat Magnus Carlsen if its moves were calculated with the UCI command "go depth 16"?
If not, how can I find the depth "d" at which Stockfish's strength surpasses top GMs?

We assume Magnus has standard time controls, and Stockfish limited only by search depth.

I would love to see a graph of Stockfish ELO (against an opponent with standard time controls) vs search depth. Does anything similar exist?

Context: I'm analyzing GM games to see when humans make mistakes, like this.
I want to set my search depth "d" so that when the engine and human moves disagree, I can be confident that the human has made a mistake.

There actually is an ambitiously worked out answer out there:

http://web.ist.utl.pt/diogo.ferreira/papers/ferreira13impact.pdf

On page 77 you get the relevant table:

depth: elo:

20    2894

19    2828

18    2761

17    2695

16    2629

15    2563

…

So my comment was slightly off, depth 20 is already very strong. Still the point remains, that it is hard to compare search depth between different engines, because it is never brute force and selectively they go much deeper than the given depth. (In the paper they used Houdini 1.5, maybe some engine expert can relate Houdini-search depth to Stockfish search depth.)


How can pawns win a whole game without any strong pieces? How can a pawn or two or three win a entire chess game on it's own?
I am playing as white pawns on the chessboard against my opponent. I tried moving to the end of the other and trading it for a strong piece. The opponent took my queen out with his bishop. This is a challenge I am willing to take on without moving any other pieces, and it can be easy eliminated.
What are a few tips I can use to defend my pawns from getting eliminated by strong pieces?
Attempts

I tried using some of my pawns to defend one pawn, but the knights and the rooks take advantage over them. (#Attempt 1)
I put 2 pawns in front of the regular pawn by match, but the rook slid under, camping the low one. Because it is on the 4 row and all my other pawns can capture it. (#Attempt 2)
I tried using 5-7 pawns, but I couldn't because the opponent needs it's turn. (#Attempt 3)
What I expect in the answer
I need tips on what I can do with some pawns that can get me a victory, and I need advantage:
Advantage Tips
Number of recommended pawns
Rare Strategies
If possible, list a few defense tips.
P.S.: I play on the internet.

Why don't you try use pawn chain to defend your pawns? Say if a pawn is at a2(white) and you want to defend  a pawn at b4 just move the pawn at a2 to a3. If a roke or a queen tries to take b4 it is defended by a3. If a roke tries take a3, it is defended by the roke at a1. It doesn't matter if you lost your queen or not. You can still win by make pawn chains and use your other peaces wisely with the pawns.


Question about the computer's valuation My friend recommended me this good community. However, I'm new to this format so I had no idea about including a chess game in my text. By looking at the previous questions, there should be some way to include my game, but I couldn't find this so instead I brought the picture of the part I was wondering about.
Why the above position almost winning for me? As indicated in the picture, chess.com's depth 18 engine is marking it as -7.4, but I have no clue about it. I couldn't find any tactics nor throughout the computer's suggestions.
Some information about that would help you answer: My chess.com rating is at 1100~1200, and been playing chess for about six months. I have mo experience in learning chess theory, only solving puzzle rush every day.

White can't defend the a3-pawn. The White king is defenceless on the queenside, and you have the knight on a great outpost near the White king, the bishop a mere ...d5-d4 away from joining the attack. The Black queen is entering the fray either via Qb6 or Qa5. both Black rooks can participate in the attack through Rc6-b6 or Rc6-a6, or along the c-file.
Basically a chess engine can't find a way to defend against the oncoming attack along the a- and b-files aimed at the White king.
Black's immediate threat is to play ...Nxa3 threatening ...Rxc2+. White defends that by playing c2-c3. White's best option at this point is to evacuate the king over to the kingside, so White's best moves of Rd1-f1 are there to clear space for the White king to walk from c1-d1-e1-f2. While he's doing that, Black is bringing his pieces quickly into White's half of the queenside attacking the king directly.


What is the record for the most stalemates in one? Is there a known record for the most possible stalemates in one in a legal position, for with and without promoted pieces? I did some constructing myself for a start.
For without promoted pieces, I found 105, counting different promotions as different moves.
[Title "me, chess.stackexchange.com 2/24/2020, Stalemate In 1"]
[FEN "kN6/P1PPPPPP/2P5/4K3/6Q1/2NBB3/1R6/R7 w KQkq - 0 1"]

For promoted pieces, I remembered a position from elsewhere on this site. I switched two pieces, made come counting deductions, and I arrived at a number of 205 moves for with promoted pieces.
[Title "me, chess.stackexchange.com 2/24/2020, Stalemate In 1"]
[FEN "R6B/3Q4/1Q4Q1/4Q3/2Q4Q/Q4Q2/pp1Q4/kBNN1KR1 w - - 0 1"]

I managed to find the ultimate records in the Die Schwable Chess Problem Database.

[Title "Anthony Stewart & Mackay Dickens, Feenschach 9/1969, 113 Stalemating Moves"]
[FEN "6R1/PPPPPP2/7R/1K6/2N1BN2/2B4p/P4P1k/3Q4 w - - 0 1"]

Source Page

[Title "Anthony Stewart & Mackay Dickens, Feenschach 1/1969, 211 Stalemating Moves"]
[FEN "4Q2R/1K4Q1/3Q4/Q4Q2/2Q4Q/4Q3/1Q4Rp/1N1BB1Nk w - - 0 1"]

Source Page


Why is it called a draw? There's no information as to why it's called a draw. Some of my students start to take out a pencil and paper and literally draw in the middle of the game.

Why is it called a draw?

I do not think that you will ever get a definitive answer. I did find an interesting article of a dedicated etymology site here.

I will quote part of it here:

  By the Oxford English Dictionary’s (OED) reckoning, the earliest
  record of draw, as in a contest that ends with no winner, comes in
  reference to an 1856 US chess match. Over the next few decades,
  writers marked off draw with quotes or italics, which shows the word
  was novel. The word was familiar by the 1870s.

  This draw is short for draw-game, which the OED finds for a “tie” by
  1825. A draw-game, in turn, is a variation on a drawn battle or drawn match. The OED dates drawn match to a 1610 letter from English
  diplomat Sir Dudley Carleton: “It concluded, as it is many times in a
  cock pit, with a drawn match; for nothing was in the end put to the
  question.” (Before pilots occupied them, game-cocks fought in
  cockpits.)

  Why such a battle or match is characterized as “drawn” is unclear:
  Indeed, etymology often ends in draws. Drawn may be clipped from
  withdrawn, as in fighters who have withdrawn from the battlefield.
  Withdraw, “to take back or away,” features an old and original sense
  of the preposition with, “against,” even though it now, ironically
  enough, means “together.” Draw, meanwhile, is related to drag. And
  withdraw itself might be a calque, or loan translation, of Latin’s
  retrahere, “to retract.”

That is probably as close as you will get.


How good is 1. e4 e5 2. Qh5 Nf6? When I play online blitz, playing black, I usually answer 1. e4 e5 2. Qh5 with 2... Nf6!? 3.Qxe5 Be7.

[FEN ""]
1. e4 e5 2. Qh5 Nf6 3.Qxe5 Be7

White often collapses quickly due to lack of development and exposed queen.

How good is this gambit objectively? Is there an established main line?

Is it playable in Blitz?  GM Nakamura played 2. Qh5 against GM Sasikiran in 2005 who responded with 2... Nc6. Nakamura lost due to an error in the middle game.

Here's the Nakamura game.  It follows the mainline 2... Nc6 but shows, to my surprise, White has a good game, contrary to everything I ever heard about moving the Queen too early.

[FEN ""]
1.e4 e5 2.Qh5 Nc6 3.Bc4 g6 4.Qf3 Nf6 5.Ne2 Bg7 6.Nbc3 d6 7.d3 Bg4 8.Qg3 Qd7 9.f3 Be6 10.Bg5 Nh5 11.Qh4 h6 12.Be3 Na5 13.Bb3 Nxb3 14.axb3 a6 15.d4 Qe7 16.Qf2 exd4 17.Bxd4 Nf6 18.O-O-O O-O-O 19.Nf4 Rhg8 20.Rhe1 Kb8 21.Kb1 g5 22.Nfe2 Rge8 23.g4 Qf8 24.Ng3 Nd7 25.Be3 Qh8 26.Nge2 Be5 27.h4 Qg7 28.Rh1 Nf6 29.Bd4 Nd7 30.Qe3 Qf6 31.hxg5 hxg5 32.Bxe5 Qxe5 33.Rh5 Rg8 34.Nd5 Rde8 35.Qc1 Qg7 36.Ne3 Nf6 37.Rh2 Rh8 38.Rg2 Nd7 39.Nd4 Rh3 40.c4 Qf6 41.Rf2 Reh8 42.b4 Qe5 43.c5 dxc5 44.bxc5 Nxc5 45.Qc3 f6 46.Rc2 Na4 47.Qb4 Bd7 48.Nb3 Rh1 49.Rxh1 Rxh1+ 50.Ka2 Nb6 51.Qf8+ Qe8 52.Qxe8+ Bxe8 53.Nc5 Nd7 54.Nxd7+ Bxd7 55.Kb3 Re1 56.Rc3 Be6+ 57.Kc2 Re2+ 58.Kc1 a5 59.Nc2 Rf2 60.Nd4 Bd7 61.Rc5 b6 62.Rd5 Kc8 63.e5 fxe5 64.Rxe5 c5 65.Nb3 Rf1+ 66.Kd2 a4 67.Nxc5 bxc5 68.Rxc5+ Kb7 69.Rxg5 Rxf3 70.Rd5 Be6 71.Rd3 Rf1 72.Rg3 Rf2+ 73.Kc3 Kb6 74.Kb4 Rf4+ 75.Ka3 Kb5 76.Re3 Bd5 77.Rd3 Bc4 78.Re3 Rd4 79.g5 Rd1 80.b3 axb3 81.Re8 Ra1+ 82.Kb2 Ra2+ 83.Kc3 Rc2+ 84.Kd4 b2 85.Rb8+ Ka4 86.g6 Bb5 87.g7 b1=Q 0-1

The opening has a few names.  Most are not complementary.  One less caustic name is the Wayward Queen Attack.  It is classified technically as the C20: KP, Patzer opening.  This opening is considered 'irregular' and does not have a more specific classification. The sub-variation we're interested in, even moreso.

There are no masters game in my database that include 2... Nf6.  There are many amateur games, but sometimes these are games by USCF C-players which does not help us here.  Out of those games, however, Black is heavily favored.  This does not mean the variation is fatal for White, per se.  It could mean that White has to play better or be better prepared than Black.

This means that, for blitz, this continuation is splendid for either side.

Here's Stockfish's continuation after 15 minutes. Stockfish rates the position above as White being up 1/3 of a pawn. I am sure this is very much within the "error noise".  I would not really trust it beyond 2 or 3 moves but it shows the gist.

[FEN "rnbqk2r/ppppbppp/5n2/4Q3/4P3/8/PPPP1PPP/RNB1KBNR w KQkq - 0 1"]

1.Qf4 Nc6 2.e5 Nd5 3.Qe4 Nb6 4.Bb5 O-O 5.Nf3 d5 6.Qe2 Nb4 7.d4 Bg4 8.a3 a6 9.Ba4 Nxa4  10.axb4 Qd7 11.c3 f6 12.O-O fxe5 13.dxe5 Bxf3 14.gxf3 Nb6 15.f4 Qf5 16.Na3 *

Okay, what you see here is a pretty sharp continuation.  Again, superb for a prepared blitz player.

Here's a game at 1 minute per side.  If the result of this game differs from the result of a game with longer controls, perhaps we can deduce that one side has a subjectively easier game and thus an advantage.

[FEN "rnbqk2r/ppppbppp/5n2/4Q3/4P3/8/PPPP1PPP/RNB1KBNR w KQkq - 0 3"]

3.Qf4 O-O 4.Nc3 Bd6 5.Qh4 Nc6 6.d4 Nxd4 7.Bd3 Re8 8.Be3 Be5 9.O-O-O Nc6 10.Nce2 d6 11.f4 Ng4 12.Qxd8 Nxd8 13.Bd2 Bf6 14.Rf1 Be7 15.Nf3 Ne6 16.Nc3 Nc5 17.Bc4 c6 18.h3 Nh6 19.g4 b5 20.Nxb5 cxb5 21.Bxb5 Bb7 22.Bxe8 Rxe8 23.g5 Nxe4 24.gxh6 Ng3 25.Rhg1 Ne2+ 26.Kd1 Nxg1 27.Nxg1 Bf6 28.b3 Bg2 29.Rf2 Bc6 30.Rf1 gxh6 31.Ne2 Kh8 32.Ng3 Bg2 33.Re1 Rxe1+ 34.Bxe1 Bxh3 35.c4 Kg7 36.Nh5+ Kg6 37.Nxf6 Kxf6 38.Ke2 Bd7 39.Bb4 Ke6 40.Kf3 h5 41.Kg3 d5 42.cxd5+ Kxd5 43.Bc3 Bg4 44.Be5 a6 45.Kh4 Be2 46.Kg5 Ke4 47.a3 Bg4 48.b4 Bd1 49.Bd6 Kd4 50.Be7 Bg4 51.Bc5+ *

A typical alien-looking game, where each move is coldly logical. It's looking drawish with Black having less than a pawn advantage according to Stockfish.  But the game is no 'trade the pieces' draw; I'd wager there are many ways to lose this.

Next will be a game at 10 minutes per move.

Edit - my machine crashed twice yesterday while grinding through the game at 10 minutes per move.  It was about halfway through the last time I looked.  It found 2 moves that could be improved by .3 pts or more.  I'm not going to rerun it.


How does opening preparation work at GM level? From what I can gather, one studies what the opponent has been playing, and prepare responses for their favourite lines. The problem is, there's no guarantee the opponent will play a given opening. For example, suppose I'm playing against Kramnik with white. Kramnik is the person who famously defeated Kasparov with the Ruy Lopez Berlin, so I prepare something special for 1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6. But then in the actual game, all I can control is the first move. After 1. e4, it's conceivable that Kramnik plays 1...d5,  1...Nc6, or 1...e6.

My guess would be that GMs have some kind of plan mapped out for every possible response - but that sounds like a formidable amount of lines to remember, especially with opening lines running 15+ moves deep.

Professional chess is hard.

Yes. Professional elite players prepare as many opening lines as they can. They have seconds who are dedicated to opening preparation (generally on a computer). The most well paid players such as Magnus Carlsen has a team of seconds. Read more about chess seconds here.
The seconds are paid for improving the master's opening preparation. Those guys are generally grandmasters. They would use database, recent trends, common sense etc to make preparation. Some players such as Maxime Vachier-Lagrave are easy to predict. MVL has been a consistent Najdorf players for years.
Of course, nobody can prepare every single possible response in chess. However, the more a GM prepares the better competitive advantage he has. Chess is a relative game - you don't need to play perfectly, you just need to play better than your opponent.
No preparation is perfect. All players must sooner or later make a new move. However, the more prepared you are the less likely you're the first player "out of book".
All professional chess players need to know extraordinary number of possible opening variations. Sometimes they don't remember the exact lines, but they know similar lines or ideas. Then, we would think over the board.
Most prepared lines are used later on against someone else.


Should I accept doubled pawns to remove the opponent's bishop pair advantage? I understand that this can be very situational which is why I don't provide a position as I am seeking some more generally applicable answer or things to consider.

Assuming that the opponent has a bishop pair would you feel that a combination that leaves me with doubled pawns and the opponent with only one bishop (but no other difference in material). is worth it? I guess another way to ask the same question is whether doubled pawns are a half point disadvantage.

In general, the two bishop advantage is worth half a pawn, while double pawns are only a minor disadvantage. Sometimes doubled pawns can be an advantage if they do not block your pieces and control important squares. OTOH, creating doubled isolated pawns on a half open file is likely to be worth the loss of a two bishop advantage.

Long term imbalances that occur early in a game are easier to deal with than those that occur late in a game. Let us take for instance the Nimzo-Indian line

[FEN ""]

1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.a3 Bxc3 5.bxc3 c5 6.e3 O-O 7.Bd3 d5 8.cxd5 exd5

Black has just allowed white to undouble the pawns that he gave up his dark square bishop to double. The key to understanding this is that the doubled pawns are not such a big deal. Black is looking to keep white's dark square bishop permanently bad (because of the pawns on e3 and d4), while getting good squares for his knights. Black's light square bishop will be not so bad (still bad because of the d5-pawn) and will also look for opportunities to trade his light square bishop for white's.


What are must read chess books every chess player has to read to become an Expert Class? I'm a Class B chess player. I would like to reach Expert Class one day. What are must read chess books. Please provide a list of books.

Some favorites:

Secrets of Modern Chess Strategy
My 60 Memorable Games
The Life and Games of Mikhail Tal
My System
Fire on Board

These books are all famous and very good.

Books by Nunn, Aagaard, Dvoretzky or Yusupov are recommended, though you have to be careful to find those suitable for your level.

The Polgar trilogy is very good and there is an upcoming series by Boris Gelfand. Two absolute top players, but nevertheless very accessible books.

Metachess: I really liked The Seven Deadly Chess Sins and Move First, Think Later.

Still, although I always read a lot of books, I would maintain that playing a lot of tournament games against stronger players is far more important.


Simul in which the GM has to make identical moves Consider two simultaneous matches in which a GM plays against Players A and B, constrained by the rule that the GM must make identical board moves in both games. Players A and B can play as usual.

Thus, for example, if Player A takes one of the GM's pawns, but Player B does not, then the GM forever loses the ability to move that pawn on Player B's board as well.

The GM only wins by winning against both Players. We can also stipulate two versions, in one of which Players A and B can cooperate, and in the other of which they cannot.

Question: Could two average Players A and B always win against the GM in this setup? Would it matter if they are allowed to cooperate or not?

(I'm not necessarily looking for a mathematical demonstration of the answer, though if there is a simple winning strategy, that would be nice. I would be glad to hear from good players about what they think would happen.)

If I understand your proposal, I think that the constraint that you are imposing would make it too easy to defeat the poor GM. Let's imagine the following pair of games with the GM playing Black:

1. e4 e5
2. Qh5 Nf6
3. Qxf7#

1. e4 e5
2. Qf3 Nf6
3. a3

Qxf7 on the first game is "checkmate" because even though Black would simply capture the queen in a normal game, they can't do it here because they can't make the same move on the second board.


Would studying the games of old players hurt my progress? I was watching a video last night by Ben Finegold on Paul Morphy and some of his games. He mentioned that some current GMs would discount Morphy's ability since all of his opponents were "terrible". However, Ben countered by observing that ok even if that's true, almost all of Morphy's moves were the best move.

I went back and looked through more of his games and like his style - extremely aggressive, and always gets his pieces out and working together, something I have a tough time doing. So the question is as in the title: for someone at my level (still very much a beginner, probably sub-1200 once my rating stabilizes), does it make sense to study older players like this, or stick with newer games? The problem I have studying newer games is that they are completely inscrutable. I can almost never figure out why certain moves are begin made once they're outside theory, so I'm not sure how much mileage I actually get out of it.

The answer from SmallChess is good. There's also an illustrative tweet from Garry Kasparov on the subject:

  For beginning chess players, studying a Carlsen game is like wanting to be an electrical engineer & beginning with studying an iPhone.


Where to keep the scoresheet Does anybody know if there is a standard "place" to keep the scoresheets of past games? I am currently using a photo album since the size of developed photos is more or less the size of my scoresheet when I fold it once, but I would like something more "professional" (that is, less homespun).

I know that there are scorebooks, but that would mean that I have to write up again all my games. I would like to keep the scoresheets, and if possible for fast review (for preparation purposes).

I used to keep scoresheets in the past, but it's tedious to keep them. Firstly, you may not recognise the writing that you recorded in hurry during the game. Besides, it is hard to be systematic with them: a single shuffle will make your games jumble up, and it will waste a lot of time.

Therefore, instead of doing it manually, I do it electronically. The main recommendation of mine is chess apps. For me, it's just Droidfish. You can get them on apps stores and it is free. Now comes the fun part. You can input your game by manual, which is playing out moves on your phone in double player mode and save it. You can also play the moves out in programs and get its pgn, then input into your phone using a cable. Either way its good.

Alternatively, chess5.com is a good website to keep your games. And do remember, if you use droidfish, keep a copy of the pgn file of your game in your computer in case your phone breaks.

Have fun


Self-Solving Chess Problems Are there any longer "problems" like this, which is white to move and mate in 6?

(Namely, where one is actually forced to achieve the "goal".)

The Wikipedia page on Joke chess problems has a section on self-solving chess problems, and it links to Tim Krabbé's Open Chess Diary, where a few more examples are in item 267. He calls them "no-brainers".


Is pawns supporting pawns a good opening strategy? For my opening strategy in most chess games I play, I usually move my pawns forward two, then one in an alternating strategy, until I have a sort of WWW shape with my pawns. That way, if anyone takes a pawn at the top, a pawn at the bottom can avenge the pawn by destroying it. I've only ever used this strategy when opening, with mixed effectiveness. Is there any better way to execute this strategy, without diverging from its core too far?

EDIT: An attempt at algebraic notation: 1. a3(a4)2. b4(b3) etc. If A is 3, then B is 4, and C is 3 again. However if A is 4 then B is 3, and C is 4. This effectively renders one of my bishops useless.

Using pawns to support pawns is a common practice.  However, it seems you're taking it too far; in the beginning of the game you probably want to focus on controlling the center and getting some pieces into the game.

Moving pawns without reason can cause holes and reduce at least one bishop to uselessness.  It can make your king hard to defend.

Play through some master games and see how they do it; they don't move a lot of pawns.


Chess position for a cake As weird as this question may seem, I am looking for a famous chess position to put in a birthday cake. Ideally the position should involve at least one knight and about 6 pieces.

Any idea of a good position matching this constraints?

How about Philidor's mate?

http://ashbyivanhoechessclub.org.uk/juniors/checkmates/philidors-mate/

[Title "Philidor's Mate"]
    [FEN "1r4k1/3Q2pp/8/6N1/6K1/8/8/8 w - - 0 1"]

    1. Qe6+ Kh8 2. Nf7+ Kg8 3. Nh6+ Kh8 4. Qg8+ Rxg8 5. Nf7#

A well known pattern that involves a (sham) Queen sacrifice, a double-check, and a smothered mate delivered by the lowly Knight.


What is the last piece to be developed, and why? Statistically speaking, for white and black, what is the last piece moved from its starting position, and why?

I think a good approach to this is to see what pieces most likely move first.

Central pawns normally always come out.

The bishops and knights come out early

If you castle early, one of the rooks plus the king will have moved

The other rook is sometimes left stationary unless there is an open file.

The queen normally gets into play.

Since you want to keep the king safeguarded, especially if castled, I would say most players would try to move the pawns in front of the castled king last or leave them on their original squares.


Why does Black want to trade off her King's Bishop in many d4 lines? I feel that in many lines starting with d4, such as the Queen's Gambit Declined, or especially the Nimzo-Indian, Black is more than happy to trade her King's Bishop for White's knight on c3. For instance, one frequent line in the Nimzo-Indian (reached in 3200 games of the chess365 database) would be the following:

[FEN ""]
1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. a3 Bxc3+ 5. bxc3

What strategic benefit does this hold for Black? She has given up the bishop pair, given White the chance to capture toward the centre with her b-pawn, in turn strengthening the d4 square for White, and moved the same piece twice in the opening. And yet, this seems to be a line where Black enjoys a higher win percentage than White, which puzzles me as it contradicts my naive understanding of opening principles.

Black gains a tempo. Black has played two bishop moves, but white has played Nc3, a3, and bxc3. Once the smoke clears, black has a lead in development with one minor piece out (vs none) and can immediately castle. Also, it doesn’t hurt that the doubled pawns are a weakness that can be exploited later.

If white does not play a3, black has no immediate need to take the knight, and it makes more sense to keep the pin. This is especially true because black does not gain the tempo without a3.


Real Chess Board which detects the moves we do We a friend and I play chess we usually don't write down our moves.

It would be great if there would be chess boards which detects our moves.

We could play using a tablet computer, but we prefer to play with a real world chess board.

Are there chess boards which detects the moves we do?

The board does not need to be smart.  For me it would be enough if it could act detect the moves and output the moves like a usb keyboard.

Yes, there are boards that record moves made automatically. This link should give you ample information about so called DGT-boards.

Because DGT-boards are pretty expensive, maybe you want to take a look at this discussion, in which the Novag Citrine board computer is proposed as a slightly cheaper alternative.

If the Novag is still too expensive, I would look further into the board computers/usb-boards, but those probably don't recognise the pieces automatically, which means they have to pressed on the starting and ending square of each move.


Team Tournament Rating Strategy In high school I played on a chess team, but that was fairly straightforward because there were no rating restrictions for teams.  Every team just grabbed the 5 strongest players and then ordered them by strength.

In most other team tournaments (except for the Chess Olympiad), there is a rating limit (i.e. the average rating of the 4 players must be less than or equal to the limit).  Additionally, most team tournaments are comprised of teams of 4 players.

That was all a build up to a request for the best strategy for a team of 4 in terms of ratings.  Given a rating limit of 2000 (as it is in this upcoming tournament), what are the best strategies to create a highly competitive team?  Similarly, what are the average ratings on each board?

For example, a team of 4 equal rated players (2000, 2000, 2000, and 2000) would likely be at a disadvantage on the top 2 boards, but would most likely have a rating edge on the lower boards.  On the other hand, a top heavy team (2500, 2000, 1800, 1700) would be more likely to have an edge on the top board, but at the cost of the second board.

A perfect answer would draw on statistics from past tournaments, but I would love to have personal anecdotes as well!

My own experience (from high school, decades ago), is that balanced teams do better. That's because most opposing teams are unbalanced.

I was first board on my team, and "league average" against other first boards.

But my lower boards were barely worse than me. They "cleaned up" against their counterparts, few of whom were "barely" weaker than me.

Hopefully your first board will get you a "random" result, and the lower boards will prevail against their opponents.


Is it ethical to spar against an engine when playing correspondence? I started playing correspondence on chess.com purely for the fun of it and to gain some deep learning (i.e. there's no prize involved).

We are about 10 moves in and coming close to me being out of book. To help my learning, I'd like to set the position up against a computer and spar against that. I am not interested in the computer's evaluation, recommended moves for me etc. I'm really just interested in practicing from a specific position.

My question is, is it ethical to spar against a computer between moves in a correspondence game?

Chess.com's site rules have the following to say:

  You can NEVER use chess programs (Chessmaster, Fritz, etc) to analyze current ongoing games unless specifically permitted (such as a computer tournament, etc). The only type of computer assistance allowed is games databases for opening lines in Turn-based Chess and Vote Chess. [...]

So it boils down to the question if playing out positions from a corr game against an engine counts as analyzing.

The answer can only be "yes" because for some possible continuations of your game, the engine provides its best moves. This is clearly an act of analysis.

There will be plenty of time to play against your engine after the game jas finished.


Chess environments for reinforcement learning I want to try some reinforcement learning techniques (borrowed from AlphaZero, etc.) and so I need a chess environment in order to run games.

I code in python, so I found python-chess but unfortunately it is too slow to generate a large amount of games. Playing 100 games with random moves (average length of ~400 moves for a random game) takes 8 seconds, which doesn't scale to higher orders of magnitude well. My profiling shows that over 99.9% of the time taken is with the library as opposed to other code, so I can't optimize any further.

Is there already an existing chess environment that is faster than this in python?

Generating high volume of data directly in an interpreting Python environment is a bad idea. Furthermore, the python-chess package is not made for high performance; the package is not a wrapper for native C/C++.

If you want to generate hundreds and thousands of games quickly, you don't have any reason for avoiding native coding such as C++. Take the Stockfish code base, modify it for making games. That was what the Leela project had done, and it worked!

Please consider going into C++. Mutlit-threading if you haven't done it already.


Online Correspondence Chess Competition Please tell me of a free and easy to use website for organizing an online correspondence chess competition for kids. Thank you very much.

You may want to use the echecsemail website. You can create round-robin tournaments for up to 9 players. For bigger player-pools, you'll have to split them in groups (or maybe talk to the admins).

They also offer the possibility of choosing an alternative starting position (for opening practice purposes mainly)

I hope those kids speak French, though!


Unable to run Stockfish on Python I know this isn't a programming forum, though it's chess-related, hence the placement on here. Basically, I'm trying to setup stockfish with Python on my PC. I installed it via pip install stockfish.
So I went on and tried to setup the Stockfish via:
from stockfish import Stockfish

stockfish = Stockfish(r'C:\Users\Acer\Desktop\chess\stockfish-11-win')

That throws a WinError 5, access denied:
Exception ignored in: <function Stockfish.__del__ at 0x0429AA48>
Traceback (most recent call last):
  File "C:\Users\Acer\AppData\Local\Programs\Python\Python38-32\lib\site-packages\stockfish\models.py", line 270, in __del__
    self.stockfish.kill()
AttributeError: 'Stockfish' object has no attribute 'stockfish'
Traceback (most recent call last):
  File "<pyshell#4>", line 1, in <module>
    emily = Stockfish(r'C:\Users\Acer\Desktop\chess\stockfish-11-win\src')
  File "C:\Users\Acer\AppData\Local\Programs\Python\Python38-32\lib\site-packages\stockfish\models.py", line 33, in __init__
    self.stockfish = subprocess.Popen(
  File "C:\Users\Acer\AppData\Local\Programs\Python\Python38-32\lib\subprocess.py", line 854, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "C:\Users\Acer\AppData\Local\Programs\Python\Python38-32\lib\subprocess.py", line 1307, in _execute_child
    hp, ht, pid, tid = _winapi.CreateProcess(executable, args,
PermissionError: [WinError 5] Zugriff verweigert

I tried different Stockfish Downloads, running the Idle or CMD as admin, re-installed and used different PCs, but I somehow don't get to work with Stockfish - anyone able to help me out bypassing the access denied? What do I miss when initializing?

The argument needs to point to the Stockfish executable. If you download the v11 zip from the Stockfish website, extract it and find the directories with the executables.
I extracted it to C:\Users\<username>\Downloads\stockfish-11-win
The executables are in C:\Users\<username>\Downloads\stockfish-11-win\Windows

To use the executable, give the path to the executable like so:
from stockfish import Stockfish

stockfish = Stockfish(r'C:\Users\<username>\Downloads\stockfish-11-win\Windows\stockfish_20011801_x64.exe')

The default value for the path you give is "stockfish", so if you add your directory with the executables to the path, and rename the exe you want to stockfish, you should be able to do:
from stockfish import Stockfish

stockfish = Stockfish()

Re. your comment:

no other stockfish related "commands" will work: OSError: [Errno 22] Invalid argument  ... so it seemingly fixed a problem but the next instantly occured.

The ArgumentError is presumably because you're passing a wrong argument. For example, I ran the commands in the readme in the github repository and it works perfectly fine.


What is the disadvantage of the move 3. ..h6 in the Queen's Gambit Declined? One of my opponents keep playing 1. d4 d5 2. c4 e6 3. Nf3 h6!? against me. Thus avoiding the main lines of the Queen's Gambit Declined that start after the normal 3) ..Nf6 4. Bg5 Be7 5. Nc3 etc.

Is there any disadvantage of the move 3) ..h6 that White may try to exploit? And if 3) ..h6 was a playable move for Black then why it is so seldom played?

I had a look at my database and I found a meager 32 games starting with 1. d4 d5 2. c4 e6 3. Nf3 h6, those are played by the lower rated players only. For the part of comparison, the Albin-Counter Gambit I have found are 100x games. Surely there must be a reason why it is so seldom played?

I understand that Black should try to develop the pieces in the opening firstly and 3) ..h6 doesn't look so terrible active, but on the other hand, the position is quite closed and after e.g. 4. Nc3 Nf6 5. Bf4 (I do not want to shut the Bishop with 5. e3) 5 .. Bd6!?, now the Black catches up in development and has a very solid position. What would you play instead?

[FEN ""]
1. d4 d5 2. c4 e6 3. Nf3 h6!?

I suspect that a good try for white here is to go into Colle-Zukertort system: http://en.wikipedia.org/wiki/Colle_System#Colle.E2.80.93Zukertort_System

Then 3...h6 is not only a tempo loss, but also a unpleasant weakness of the king side.


A Consistent Grunfeld Repertoire I'm starting to play against stronger competition who know how to play their openings, so I'm trying to figure out my repertoire. I have recently decided to stick to playing the Grunfeld against 1.d4, and prepared some responses against those who avoid playing an early c4 and go for the Tromp/London/Barry etc.

However I'm a bit stuck when it comes to playing against openings where White avoids an early d4, and goes for a Nf3/g3/Bg2/0-0 and c4 setup before going d4, maybe even avoiding d4 altogether and going for a b3 hypermodern approach.

Since Grunfeld is all about letting White achieve a broad center and attacking it from afar, it feels awkward when White refuses to take the center immediately.

I can look up some specific responses, such as going 1.c4 e5 and aiming for a Reversed Dragon, but I'd rather have a more consistent repertoire that at least involves a Kingside fianchetto, so that at least there is a chance that the game might transpose back into a Grunfeld.

Of course if this means that I might get move-ordered into a bad position then I'll play something else, but I find it hard to believe a Kingside fianchetto can ever really be bad against the kind of hypermodern White opening I described.

Any experienced Grunfeld players want to chime in on this?

Anyway you cannot prevent someone avoiding the Grunfeld by move order. For instance, 1.c4, Nf6; 2. Nc3, g6; 3.e4, and it's done with the Grunfeld. The trick is it is better to play Grunfeld and KID (Bologan's KID book has a chapter devoted to this, i think) complementarily, even against the fianchetto variation. Quality chess books by Avrukh on the grunfeld are excellent, so are also The safest grunfeld and in a lesser measure Dembo's (but not bad at all). I think there is no other way out. You could also listen to Svidler's lectures on chess24, they are excellent.


How to limit lines in scid vs pc in annotate mode? I would like to reduce the number of lines calculated by the engine to speed up the analysis but I cannot find the appropriate option for that. Does anybody know how to do this in Scid vs PC?

In Scid vs PC, after you turn on an engine, a window with analysis opens. In that window you can see icons like Stop Engine, Add Move, Add Variation etc. (see picture below).

Among them, there is a small box with a number (marked by a red circle in the picture below), namely the number of lines suggested by the engine. Adjust that according to your preference. If I understood your question correctly, that should solve your problem. Just for the sake of completeness, I have the version  4.13 of Scid vs PC.


Which is better-Stockfish 10 or AlphaZero? I know AlphaZero (an AI) is one of the best top chess engines but Stockfish is also improving. Which one is better at chess? Also is there a new Stockfish level?

We can't say for sure since AlphaZero is a private engine, i.e. we don't have games between it and the latest versions of Stockfish. Still, if AlphaZero hasn't improved since it was unveiled, it will likely lose to the latest version of Stockfish. That's because AlphaZero beat Stockfish 8 by +155 = 839 -6, which is an elo difference of about 50. The latest versions of Stockfish are capable of beating Stockfish 8 by about 150 elo (see also this). It's true that elo isn't transitive (i.e. engine A can beat engine B, which beats engine C, but C could still beat A in a match); however, the differences are so large that it would be incredible if AlphaZero is capable of beating the latest versions of Stockfish. You ask about Stockfish 10 (not latest Stockfish), which still beats Stockfish 8 by 100 elo, so it should be capable of beating AlphaZero as well.
Having said that, Leela Chess Zero is an engine based on AlphaZero techniques. It incorporates many new innovations not in the original paper, and therefore should be stronger than AlphaZero. Indications are it's competitive with Stockfish, and (for now at least) stronger: it won the most recent version of the Top Chess Engine Championship by five games - an elo difference of about 15.
Caveats:

In the world of computer chess, 100 games is an incredibly small sample size. Engine developers regularly need tens of thousands of games to conclusively say that one engine is stronger than the other. These games are played at bullet time controls, which isn't really chess as us humans understand it. Still, we can't play ten thousand games at long time controls - that takes too long - so we have to be satisfied with 100.
Stockfish continues to improve. As of time of writing, Leela has kinda stalled while a new net is being trained. So while Leela was (probably) stronger two months ago, it might not be the strongest engine right now.
Stockfish is not Leela's only competitor. In fact just two seasons ago, Leela actually failed to qualify for the superfinal, losing out to AllieStein. Like Leela, AllieStein is a neural network engine; unlike Leela, AllieStein includes human knowledge. Plus, as of time of writing, all three of Leela / AllieStein / Stockfish are behind Stoofvlees in the qualification tournament for the superfinal.

You might be interested in the ongoing Season 18 of the Top Chess Engine Championship, live games are available here.
tl; dr: AlphaZero is probably inferior to Stockfish 10, and even more so to the latest versions of Stockfish. Leela is at least competitive with Stockfish, and there's a good chance it's stronger (right now) as well. For the question "who is the strongest engine right now?", the situation is fluid; there are several engines that could all claim to be #1 at any one time. For the foreseeable future, this situation is likely to remain the case.
Edit: Deepmind acknowledges that AlphaZero would probably lose to the latest versions of Stockfish and Leela. They don't perceive it as a challenge, however, because they're not a chess engine company and don't view having the best engine as a big deal.