From bb56779cb6e46418783e4253e424d397921335d7 Mon Sep 17 00:00:00 2001 From: Stefan Geschwentner Date: Tue, 24 Jul 2018 12:16:49 +0200 Subject: [PATCH 1/1] Revert "Tweak reductions formula: 0.88 * depth + 0.12" This patch reverts the recent commit called "Tweak reductions formula, etc." The decisions for the revert decision were as follows: 1) The original commit called "Tweak reductions formula: 0.88 * depth + 0.12" showed bad scaling at in a Very Long Time Control (VLTC) test: VLTC (180+1.8): LLR: -1.59 (-2.94,2.94) [0.00,5.00] Total: 14968 W: 2247 L: 2257 D: 10464 http://tests.stockfishchess.org/tests/view/5b559ffa0ebc5902bdb84f36 2) So there was a suspicion that the original fast passing LTC test which lead us to accept the patch may have been a statistical accident, so we organized a match against the previous master at LTC to get an Elo estimate for the patch: LTC match: ELO: -1.83 +-2.1 (95%) LOS: 4.3% Total: 36018 W: 6018 L: 6208 D: 23792 http://tests.stockfishchess.org/tests/view/5b55f8110ebc5902bdb8526f 3) Based on these results, we ran a simplification test with [-3..1] bounds for the revert at LTC: LTC: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 41501 W: 7107 L: 7020 D: 27374 http://tests.stockfishchess.org/tests/view/5b5738670ebc5902bdb86932 4) So we revert. Bench: 4491691 --- src/search.cpp | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/src/search.cpp b/src/search.cpp index 89636f23..af7a5c13 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -153,8 +153,7 @@ void Search::init() { for (int d = 1; d < 64; ++d) for (int mc = 1; mc < 64; ++mc) { - double slope = d > 2 ? 0.88 * d + 0.36 : d; - double r = log(slope) * log(mc) / 1.95; + double r = log(d) * log(mc) / 1.95; Reductions[NonPV][imp][d][mc] = int(std::round(r)); Reductions[PV][imp][d][mc] = std::max(Reductions[NonPV][imp][d][mc] - 1, 0); -- 2.39.2