From: Marco Costalba Date: Mon, 24 Dec 2012 08:07:17 +0000 (+0100) Subject: Introduce Null Threat extension X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=894c43a1d648d4cf160de006bde59aa5b6ba0190;hp=894c43a1d648d4cf160de006bde59aa5b6ba0190 Introduce Null Threat extension In case of null search at low depths returns a fail low due to a threat then, rather than return beta-1 (to cause a re-search at full depth in the parent node), we set a flag threatExtension = true (false by default) that will cause moves that prevent the threat to be extended of one ply in the following search. Idea and patch is by Lucas Braesch. Lucas also did the tests: 1500 games in 5"+0.05": SF_threatExtension vs SF_20121222: 366 - 331 - 803 [51.2%] LOS=90.8% 3000 games in 10"+0.1": SF_threatExtension vs SF_20121222: 610 - 559 - 1831 [50.8%] LOS=93.2% Tests confirmed by Gary after 10570 games, ELO: 2.79 +- 99%: 8.72 95%: 6.63 LOS: 94.08% Wins: 1523 Losses: 1438 Draws: 7607 And finally by me at 15"+0.05, single thread, 3824 games threatExtension vs master 768 - 692 - 2364 +7 ELO bench 4918443 ---