I have problem with Delta Pruning.
From chess wiki:
It's ok...but..For safety reasons, delta pruning should be switched off in the late endgame, since otherwise quiescence search would be blind to insufficient material issues and transitions into won endgames made at the expense of some material.
Problem:
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White to move.
White close to mate (win: arround 600-800 cp).
White have !Queen!-> important, Rook, Pawns >> greater material than in end game.
White Queen or Rook is under attack. (still white to move)
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In the next step white lose Queen or Rook.
When i take back and re-search, this does not happen again.
(I was thinking the hash table the reason, but this happens after i implemented delta pruning)
Fruit 2.1: Dont prune Queen capture in a Qsearch
Kontra: Most (top) engine does not use it.
Stockfish:
Code: Select all
futilityBase > -VALUE_KNOWN_WIN
Why is it so high?
Kontra: Senpai, Rodent does not use it, but still works well.
DiscoCheck:
Code: Select all
best_score = std::max(best_score, opt_score); // beware of fail soft side effect
Currently delta margin is: Pawn endgame value. I tried: 2*Pawn value.
I think the "alpha mate" should be caught. Is this a good solution?
Kontra: Most (top) engine does not use it.
I'm clueless.
Has anyone been like that? What did it solve?
Sorry if it is difficult to understand.
Thank's, Tamás