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Insufficient mating material in antichess #12966

Open johndoknjas opened 1 year ago

johndoknjas commented 1 year ago

In Antichess, Lichess can correctly detect when both sides have no way to win (e.g., a lone dark-squared bishop against a lone light-squared bishop). However, take a position like this. In this position, White has no legal way to win, while Black can potentially win if White blunders. As such, Lichess correctly wouldn't stop the game here and call it a draw. However, if Black were to now forfeit on time, White would be awarded the win. In such a scenario, I think the ideal outcome would be declaring the game drawn.

These cases would include any positions where one side just has a bishop left, and the opposing side has at least a bishop on the opposite colour.

niklasf commented 1 year ago

It's tricky, because in principle white can win by stalemate with the same material combination, even taking into account color complexes: https://lichess.org/analysis/antichess/6bB/6P1/8/8/8/8/8/8_w_-_-_0_1.

johndoknjas commented 1 year ago

@niklasf Ah good point, I hadn't considered that.