Encourage rook lift to third rank
authorxoto10 <buylow001@gmail.com>
Mon, 23 Sep 2019 07:24:13 +0000 (08:24 +0100)
committerStéphane Nicolet <cassio@free.fr>
Mon, 23 Sep 2019 07:50:34 +0000 (09:50 +0200)
commitdefa1ccaa9c145b0ccff38a1ae660c052d753e81
treef175f9559788a541ea9ab5326675c7d887219ed8
parent302e0f70c653bfcca4338d7be71dfdd1166da910
Encourage rook lift to third rank

This change to the Rook psqt encourages rook lifts to the third rank
on the two center files.

STC 10+0.1 th 1 :
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 40654 W: 9028 L: 8704 D: 22922
http://tests.stockfishchess.org/tests/view/5d885da60ebc5906dd3e9fcd

LTC 60+0.6 th 1 :
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 56963 W: 9530 L: 9196 D: 38237
http://tests.stockfishchess.org/tests/view/5d88618c0ebc5906dd3ea45f

Thanks to @snicolet for mentioning that Komodo does this a lot and
Stockfish doesn't, which gave me the idea for this patch, and to
@noobpwnftw for providing cores to fishtest which allowed very quick
testing.

Future work: perhaps this can be refined somehow to encourage this
on other files, my attempts have failed.

Closes https://github.com/official-stockfish/Stockfish/pull/2322

Bench: 3950249
src/psqt.cpp