Timeout with insufficient material should be a draw

[tezer2d]

FIDE rules don't say "Timeout vs. Insufficient material" but "Timeout vs. No possible sequence of legal moves that would lead to checkmate". Strictly enforcing this rule would be impossible since it could require checking large numbers of moves, so usually most chess programs use shortcuts, e.g. https://lichess.org/faq#timeout

[lucasmeneghin]

What is the difference? Thats just the nomenclature Either way if white cant possibly mate black and black timeouts it should be a draw, not win for white.

[tezer2d]

if white cant possibly mate black and black timeouts it should be a draw

yes and as I said, proving that white can't possibly mate black requires looking at all possible sequences of legal moves. And that can be impossible to compute. So your feature request can't be implemented. Only a compromise could be implemented, e.g. assuming that it's enough to prove that white can't mate black in n moves, or assuming that if white has more than a king then checkmate is always possible

[lucasmeneghin]

Well, my feature request is exactly what can be implemented Timeout vs insufficient material is ALWAYS a case of timeout vs no legal sequence of moves, so it should always be a draw

[icecream17]

Incidentally, while solving this problem very fast 100% guaranteed is mathematically impossible (for a general nxn board), it is possible to achieve 100% solving on an 8x8 board while being pretty much 100% very fast (see https://chasolver.org/)

(but realistically this issue would probably be solved by just checking the insufficient material case) (though the website does say it's ready to be used

[lucasmeneghin]

@SebLague tagging you so it gets special attention because this is basically a must for the tournament, since its base chess rules (unless you decide not to follow FIDE) I found the chasolver repo very helpful for understanding this problem better https://github.com/miguel-ambrona/D3-Chess/

• King vs Anything - Mate not possible for lone king
• In a King + Bishop vs King + Bishop situation, if the bishops are of the same color, it's a draw. However, if the bishops are of different colors, a checkmate is possible.
• A King + Knight vs King + Knight situation always has the potential for a checkmate.
• Similarly, in a King + Pawn vs King + Knight/Bishop scenario, a checkmate is also possible.

The other edge cases dont necessarily need to be included because they are less likely to happen, even lichess and chess.com have different approaches sometimes The analyser also helps with this https://chasolver.org/analyzer.html

[icecream17]

(pawnless insufficient material solver)

insufficient material:

• [x] king vs king
• [x] lone knight
• [ ] bishops of one color (this is detected in the case where neither side has more than one bishop of the same color, and admittedly counterexamples are very rare)

insufficient material for one side (if the other side times out, then the side with insufficient material can't win so it is a draw)

• [ ] lone knight vs queens
• [ ] bishops of one color vs bishops of same color, rooks and/or queens

[SebLague]

Thanks, I'll make sure the final tournament is run with this rule in place