'dead position'

Lichess can't detect fortresses. Sadly it seems it also can't detect forced stalemates.

Reminds me of this game

@Cedur216 said in #2:

Lichess can't detect fortresses. Sadly it seems it also can't detect forced stalemates.
IMHO the problem is that the position istechnically not a stalemate yet as black is to move. And the algorithm is not smart enough to recognize that any legal move by black would be a stalemate.

It is a draw as regardless of what black plays it is stalemate thus there is no legal set of moves that can lead to white winning (or black winning).

This is a fascinating example! According to FIDE: "The game is drawn when a position has arisen in which neither player can checkmate the opponent’s king with any series of legal moves. The game is said to end in a ‘dead position’. This immediately ends the game, provided that the move producing the position was legal."
I guess the engine doesn’t interpret it correctly, since the last move that would lead to that position wasn’t actually played. So, because the dead position never legally appeared on the board, the draw can’t be claimed.

@ajedrezconzeta said in #6:

So, because the dead position never legally appeared on the board, the draw can’t be claimed.
It's definitely a draw under FIDE rules. As soon as g6 is played, the game immediately ends and is a draw, even before Black attempts to make a move.

Those kind of positions where one side cannot win are very difficult to detect in general, so it is not feasible to look for them at all. Sure, in most cases you could come up with a simple logic to detect them, but there are just many variations of that theme, and most of them would require deep search.

Luckily, those cases are pretty rare in practice.

@kumuDan What has your game to do with this thread? This is an easy win for White, no?

So even if lichess codified it, would adding an instant stalemate for fortresses be beneficial or not?