There is now a public 6 piece tablebase (Nalimov) and a secret 7 piece tablebase (Lomonosov).
What is the longest actually recorded stretch of over the board game between two people during which all the moves by each player were best moves, as checked against a tablebase, that has been discovered?
What is the longest actually recorded stretch of over the board game between two people during which all the moves one player were best moves, as checked against a tablebase, that has been discovered?
https://en.wikipedia.org/wiki/Chess_endgame#Longest_forced_win
In May 2006 a record-shattering 517-move endgame was announced (see first diagram). Marc Bourzutschky found it using a program written by Yakov Konoval. Black's first move is 1. ... Rd7+ and White wins the rook in 517 moves. This was determined using the easier-to-calculate depth-to-conversion method, which assumes that the two sides are aiming respectively to reduce the game to a simpler won ending or to delay that conversion. Such endgames do not necessarily represent strictly optimal play from both sides, as Black may delay checkmate by allowing an earlier conversion or White may accelerate it by delaying a conversion (or not making one at all).
In September 2009, it was found that the distance to mate (not conversion) in a similar position to the Bourzutschky-Konoval position was 545 (see diagram).[19] The same researchers later confirmed that this (along with variations of it) is the longest 7-man pawnless endgame,
With pawns, the longest 7-man endgame is the one depicted in the second diagram. White takes 6 moves to promote his pawn to a Knight, after which it takes him another 543 moves to win the game.[20]
The fifty-move rule is ignored in the calculation of these results and lengths.
/ I see you wanted to know the best that humans have done in actual over the board games. Someone running an enormous database would have to check endgame play in all games that get down to six or seven pieces against the tablebases. I haven't heard that anyone is doing that. I would guess that a majority of grandmaster games are decided without ever going that far into the endgame.
WIthout doubt, the best than humans have done would be pitiable in comparison with what has been achieved by the silcon wizards.
/There is also no prize for "best moves". What does that mean anyway? The shortest forced win against the optimal moves designed to postpone the loss as long as possible? One would have to be playing against an opponent with a tablebase to achieve anything of note.
There is now a public 6 piece tablebase (Nalimov) and a secret 7 piece tablebase (Lomonosov).
What is the longest actually recorded stretch of over the board game between two people during which all the moves by each player were best moves, as checked against a tablebase, that has been discovered?
What is the longest actually recorded stretch of over the board game between two people during which all the moves one player were best moves, as checked against a tablebase, that has been discovered?