HCha/Stockfish
1
0
Fork 0
mirror of https://github.com/HChaZZY/Stockfish.git synced 2025-12-21 09:37:16 +08:00
Code Issues Packages Projects Releases Wiki Activity

Don't special case for abs(beta) >= VALUE_MATE_IN_MAX_PLY

Browse Source 
Remove from the search this special case and apply
null search and razoring also in mate positions.

Tested in no-regression mode and passed both

STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 65431 W: 10860 L: 10810 D: 43761

and LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 34928 W: 4814 L: 4713 D: 25401

This patch kicks in only in mate positions and in
these cases it seems beneficial in finding mates
faster as Yery Spark measured on the Chest mate suite:

Total number of positions 6425
Fixed nodes 200K per position

master: 1049
new:    1154

And also the 5446 'hard' positions again with 2000K nodes
(those not found by both engines in 200K nodes):

master: 1069
new:    1395

bench: 7710548
This commit is contained in:
Eelco de Groot
2014-06-16 21:46:42 +02:00
committed by Marco Costalba
parent 66c93245e0
commit 55a3e0af8d
1 changed files with 5 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
src/search.cpp
View File

@@ -566,7 +566,6 @@ namespace {
&& depth < 4 * ONE_PLY && depth < 4 * ONE_PLY
&& eval + razor_margin(depth) <= alpha && eval + razor_margin(depth) <= alpha
&& ttMove == MOVE_NONE && ttMove == MOVE_NONE
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
&& !pos.pawn_on_7th(pos.side_to_move())) && !pos.pawn_on_7th(pos.side_to_move()))
{ {
if ( depth <= ONE_PLY if ( depth <= ONE_PLY
@@ -594,7 +593,6 @@ namespace {
&& !ss->skipNullMove && !ss->skipNullMove
&& depth >= 2 * ONE_PLY && depth >= 2 * ONE_PLY
&& eval >= beta && eval >= beta
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
&& pos.non_pawn_material(pos.side_to_move())) && pos.non_pawn_material(pos.side_to_move()))
{ {
ss->currentMove = MOVE_NULL; ss->currentMove = MOVE_NULL;
@@ -604,7 +602,8 @@ namespace {
// Null move dynamic reduction based on depth and value // Null move dynamic reduction based on depth and value
Depth R = 3 * ONE_PLY Depth R = 3 * ONE_PLY
+ depth / 4 + depth / 4
+ int(eval - beta) / PawnValueMg * ONE_PLY; + (abs(beta) < VALUE_KNOWN_WIN ? int(eval - beta) / PawnValueMg * ONE_PLY
: DEPTH_ZERO);
pos.do_null_move(st); pos.do_null_move(st);
(ss+1)->skipNullMove = true; (ss+1)->skipNullMove = true;
@@ -619,7 +618,7 @@ namespace {
if (nullValue >= VALUE_MATE_IN_MAX_PLY) if (nullValue >= VALUE_MATE_IN_MAX_PLY)
nullValue = beta; nullValue = beta;
if (depth < 12 * ONE_PLY) if (depth < 12 * ONE_PLY && abs(beta) < VALUE_KNOWN_WIN)
return nullValue; return nullValue;
// Do verification search at high depths // Do verification search at high depths
@@ -699,6 +698,7 @@ moves_loop: // When in check and at SpNode search starts from here
singularExtensionNode = !RootNode singularExtensionNode = !RootNode
&& !SpNode && !SpNode
&& depth >= 8 * ONE_PLY && depth >= 8 * ONE_PLY
&& abs(beta) < VALUE_KNOWN_WIN
&& ttMove != MOVE_NONE && ttMove != MOVE_NONE
&& !excludedMove // Recursive singular search is not allowed && !excludedMove // Recursive singular search is not allowed
&& (tte->bound() & BOUND_LOWER) && (tte->bound() & BOUND_LOWER)
@@ -764,8 +764,7 @@ moves_loop: // When in check and at SpNode search starts from here
if ( singularExtensionNode if ( singularExtensionNode
&& move == ttMove && move == ttMove
&& !ext && !ext
&& pos.legal(move, ci.pinned) && pos.legal(move, ci.pinned))
&& abs(ttValue) < VALUE_KNOWN_WIN)
{ {
assert(ttValue != VALUE_NONE); assert(ttValue != VALUE_NONE);