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Movecount pruning reduction logic

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This patch refines search reduction logic in case the position is not a former PV node and is pruned based on move count.

passed STC
https://tests.stockfishchess.org/tests/view/5e8092bde42a5c3b3ca2ed35
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 78848 W: 15480 L: 15170 D: 48198
Ptnml(0-2): 1406, 9310, 17773, 9438, 1497

passed LTC
https://tests.stockfishchess.org/tests/view/5e80bb13e42a5c3b3ca2ed4b
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 86596 W: 11451 L: 11033 D: 64112
Ptnml(0-2): 624, 7993, 25687, 8329, 665

closes https://github.com/official-stockfish/Stockfish/pull/2605

Bench: 5138771
This commit is contained in:
Praveen tummala
2020-03-30 10:22:42 +05:30
committed by Joost VandeVondele
parent f2430bf034
commit b7ecdaada7
2 changed files with 9 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
AUTHORS
View File

@@ -1,4 +1,4 @@
# List of authors for Stockfish, as of January 7, 2020 # List of authors for Stockfish, as of March 30, 2020
Tord Romstad (romstad) Tord Romstad (romstad)
Marco Costalba (mcostalba) Marco Costalba (mcostalba)
@@ -123,6 +123,7 @@ Pasquale Pigazzini (ppigazzini)
Patrick Jansen (mibere) Patrick Jansen (mibere)
pellanda pellanda
Peter Zsifkovits (CoffeeOne) Peter Zsifkovits (CoffeeOne)
Praveen Kumar Tummala (praveentml)
Rahul Dsilva (silversolver1) Rahul Dsilva (silversolver1)
Ralph Stößer (Ralph Stoesser) Ralph Stößer (Ralph Stoesser)
Raminder Singh Raminder Singh

10
src/search.cpp
View File

@@ -962,6 +962,7 @@ moves_loop: // When in check, search starts from here
value = bestValue; value = bestValue;
singularLMR = moveCountPruning = false; singularLMR = moveCountPruning = false;
ttCapture = ttMove && pos.capture_or_promotion(ttMove); ttCapture = ttMove && pos.capture_or_promotion(ttMove);
bool formerPv = ttPv && !PvNode;
// Mark this node as being searched // Mark this node as being searched
ThreadHolding th(thisThread, posKey, ss->ply); ThreadHolding th(thisThread, posKey, ss->ply);
@@ -1054,8 +1055,8 @@ moves_loop: // When in check, search starts from here
&& tte->depth() >= depth - 3 && tte->depth() >= depth - 3
&& pos.legal(move)) && pos.legal(move))
{ {
Value singularBeta = ttValue - (((ttPv && !PvNode) + 4) * depth) / 2; Value singularBeta = ttValue - ((formerPv + 4) * depth) / 2;
Depth singularDepth = (depth - 1 + 3 * (ttPv && !PvNode)) / 2; Depth singularDepth = (depth - 1 + 3 * formerPv) / 2;
ss->excludedMove = move; ss->excludedMove = move;
value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, singularDepth, cutNode); value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, singularDepth, cutNode);
ss->excludedMove = MOVE_NONE; ss->excludedMove = MOVE_NONE;
@@ -1143,13 +1144,16 @@ moves_loop: // When in check, search starts from here
if (ttPv) if (ttPv)
r -= 2; r -= 2;
if (moveCountPruning && !formerPv)
r++;
// Decrease reduction if opponent's move count is high (~5 Elo) // Decrease reduction if opponent's move count is high (~5 Elo)
if ((ss-1)->moveCount > 14) if ((ss-1)->moveCount > 14)
r--; r--;
// Decrease reduction if ttMove has been singularly extended (~3 Elo) // Decrease reduction if ttMove has been singularly extended (~3 Elo)
if (singularLMR) if (singularLMR)
r -= 1 + (ttPv && !PvNode); r -= 1 + formerPv;
if (!captureOrPromotion) if (!captureOrPromotion)
{ {