Smart pruning doesn't activate if only one move isn't a proven loss

LeelaChessZero / lc0

The rewritten engine, originally for tensorflow. Now all other backends have been ported here.

GNU General Public License v3.0

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Smart pruning doesn't activate if only one move isn't a proven loss #1421

Closed Naphthalin closed 3 years ago

Naphthalin commented 4 years ago

TCEC S19 DivP, game 130 (Stoofvlees vs Lc0), move 40 black. Leela spent 3:50 on deciding to play 40. ... Kf8; the only legal alternative 40. ... Kh8 41. Qh7# is checkmate.

In my opinion, smart pruning should kick in if only one legal move doesn't lose the game, similar to how we play instamoves when there is only one legal move.

FEN: 6k1/1qr2bp1/5NQp/4P3/1p6/4RP1P/6P1/6K1 b - - 9 40 Link to game: https://tcec-chess.com/#div=p&game=130&season=19

Naphthalin commented 3 years ago

Never realized that I opened this issue; PR is #1489 which is already merged.