From: Marco Costalba <mcostalba@gmail.com>
Date: Mon, 25 May 2009 14:48:47 +0000 (+0100)
Subject: Passed pawns evaluation tweak
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=738bf66a2d04d27ce8c5481fef52dc3adc3cafe1;hp=738bf66a2d04d27ce8c5481fef52dc3adc3cafe1

Passed pawns evaluation tweak

Do not penalize if in our adavncing pawn's path there are
non-pawns enemy pieces. Especially if they can be attacked
by us.

Patch is mine, but original idea and also fixing of a first, wrong,
version of the patch is from Eelco de Groot.

Tests with Joona framework seems to confirm patch is good

Results for patch 'disabled'   based on 5776 games: Win percentage:
41.309  (+- 0.526)  [+- 1.053]
Results for patch 'enabled'  based on 6400 games: Win percentage:
42.422  (+- 0.500)  [+- 1.000]

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
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