Author: Mike S.
Date: 19:11:01 12/07/02
In a WinBoard match game Delfi 3.2 - Crafty 18.15, the following position occured before the 92nd move, after Crafty allowed it's last pawn to be exchanged (maybe that was forced, though don't think it was, didn't analyse it): [D]R7/3b1k2/8/6R1/4r2K/7P/3r2P1/8 w - - 0 92 Crafty, but also other engines, evaluate that position with a *big* advantage for black, sometimes up to -2.x. No combination involved (the material balance didn't change the next 80 moves). 4-piece tbs. + RB-R, RN-R were installed. I'd like to ask strong chessplayers especially, but also anybody else, if the following is correct: 1. Since RB-R is a theoretical draw (with few exceptions), the value of the black bishop is *less* than usual here. 2. White's pawns are connected passers and therefore *more* valuable than +2. 3. Crafty knows the basic RB-R draw within it's algos (IIRC; I didn't check it now) and will evaluate it correctly even in the quiescence search. 4. For these reasons, the position should be evaluated less (for Black) than the material balance, IOW between 0.00 and -1.00 (max.) if not with a white advantage even (White's pawns seem to be more dangerous than Black's bishop). Does the presence of the additional 2 rooks change the evaluation that much? We have RRPP vs. RRB. I wonder if something "anti human" in Crafty might be responsible for the too optimistic evaluation... Black has the potential to create mate threats still, easier than in RB-R. The game lasted until move no. 227 (!!) until it was finally drawn... Regards, M.Scheidl
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