draw for insufficient material

shouldnt it be a draw?

As stated in the rules :
"In the event of one player running out of time, that player will usually lose the game. However, the game is drawn if the position is such that the opponent cannot checkmate the player's king by any possible series of legal moves (FIDE handbook §6.9)"

...



The system gave me a loss tho... even if by no means white was check-mating me!
(I was the black)

Oh yeah!

You could have lost if you did not take the bishop, promoted the pawn to a knight, and got this position:

lichess.org/analysis/knB5/8/1K6/8/8/8/8/8_w_-_-_0_1

In this case, Bb7# is mate.

Makes me wonder, if there was a black pawn also on h4 would it be drawn or lost? The FIDE rule referenced would make it a draw because the king is forced to take the bishop, but I wonder if the Lichess evaluator is smart enough to see that or if it only considers material.

@browni3141 : with a black pawn on h4 it is won for white from the lichess perspective.
I tried it with this FEN: 8/8/8/4K2p/5q2/7k/6pp/7B w - - 0 1 and set the time control to 1 min. Stockfish first takes the queen, I move the pawn to h4 (now after first move my time starts to run), Stockfish takes the pawn and I let the time run..
result: win for white

Lichess currently only uses some simple rules to check for this, partly because situations like this are extremely rare. In 99.9% of cases it's like in OP's game where it's not actually impossible to mate.

There is a proposal to improve this and properly detect all situations but it's not yet clear whether it will be accepted since it will take a decent amount of computational power to check this on all relevant games.

@Sputnik_Monroe Thanks for checking!

@benwerner Aren't there some positions where it would be difficult for a computer to determine if a helpmate is possible? Although they might only exist as compositions. The way Lichess handles it now is fine, IMO.

Black CAN win this game, anyway, so it's a win for white on time. You can read this for better info : lichess.org/faq#timeout .

@browni3141 It's definitely not something that can be determined at a glance but somebody managed to come up with a pretty performant algorithm that can handle all cases in just a few milliseconds and the vast majority in microseconds.

That's definitely good enough to handle even the vast number of games on Lichess with a decent dedicated server. But ofc that's still not free and I'm also not sure whether it's worth it given that the current behavior is certainly good enough for 99.9% of cases.

Losing on time, drawing and insufficient material
In the event of one player running out of time, that player will usually lose the game. However, the game is drawn if the position is such that the opponent cannot checkmate the player's king by any possible series of legal moves (FIDE handbook §6.9).

In rare cases this can be difficult to decide automatically (forced lines, fortresses). By default we always side with the player who did not run out of time.

Note that it can be possible to mate with a single knight or bishop if the opponent has a piece that could block the king.