Small improvement

[tomitank]

Hi all!

Very small improvement:
don't try verify the "checks" after null move pruning (first ply).
It is unnecessary, because the opponent had to leave the check.

-Tamás

[Ras]

Not sure whether I understand correctly... but when one side leaves check, this can generate check for the other side, isn't that an issue?

[tomitank]

After null move, the check verify is unnecessary.

Code: Select all

			if (nullOK)
			{
				TakeNullMove(); // eg: replace side

				Score = -AlphaBeta(-beta, -beta+1, depth-4, false, true);

				// This call: AlphaBeta -> next node for opponent
				// No need to verify again the check at next node

				TakeBackNull(); // eg: replace side

				if (Score >= beta) {
					return Score;
				}
			}

Code: Select all

	function AlphaBeta(alpha, beta, depth, nullMove, afterNullMove) {
		......
		if (afterNullMove == false) { // Unnecessary after null move (at first node)
			inCheck = isCheck();
		}
		......
	}

If you predefine the outcome of a move, the code is even simpler.

[Evert]

You can do even better if you test for alignment of the origin (Queen-alignment) and destination (Superpiece or Amazon alignment). If neither matches, the move cannot be a checking move.

[tomitank]

I'm already using it.