From 426f55b78d8d83ad779772dc46ad4f645177c4c4 Mon Sep 17 00:00:00 2001 From: Marco Costalba Date: Sat, 20 Mar 2010 12:42:23 +0100 Subject: [PATCH] Use fail soft in null search If null search fails high return null value instead of beta. With TT hash there may be a small advantage for fail-soft since storing slightly better bounds may cause slightly more hash hits. After 990 games at 1+0 Mod vs Orig +171 =665 -154 +6 ELO Signed-off-by: Marco Costalba --- src/search.cpp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/search.cpp b/src/search.cpp index 4592ac08..f5552e78 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -1379,12 +1379,12 @@ namespace { if (nullValue >= beta) { if (depth < 6 * OnePly) - return beta; + return nullValue; // Do zugzwang verification search Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID); if (v >= beta) - return beta; + return nullValue; } else { // The null move failed low, which means that we may be faced with // some kind of threat. If the previous move was reduced, check if -- 2.39.2