Limit double extensions

mirror of https://github.com/opelly27/Stockfish.git synced 2026-05-20 13:17:44 +00:00

Double extensions can lead to search explosions, for specific positions.
Currently, however, these double extensions are worth about 10Elo and cannot
be removed. This patch instead limits the number of double extensions given
to a maximum of 3.

This fixes https://github.com/official-stockfish/Stockfish/issues/3532
where the following testcase was shown to be problematic:

```
uci
setoption name Hash value 4
setoption name Contempt value 0
ucinewgame
position fen 8/Pk6/8/1p6/8/P1K5/8/6B1 w - - 37 130
go depth 20
```

passed STC:
https://tests.stockfishchess.org/tests/view/60c13161457376eb8bcaaa0f
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 73256 W: 6114 L: 6062 D: 61080
Ptnml(0-2): 222, 4912, 26306, 4968, 220

passed LTC:
https://tests.stockfishchess.org/tests/view/60c196fb457376eb8bcaaa6b
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 166440 W: 5559 L: 5594 D: 155287
Ptnml(0-2): 106, 4921, 73197, 4894, 102

closes https://github.com/official-stockfish/Stockfish/pull/3544

Bench: 5067605

This commit is contained in:

Joost VandeVondele

2021-06-09 23:23:13 +02:00

committed by

Stéphane Nicolet

parent 785b708097

commit 559942d64d

2 changed files with 11 additions and 4 deletions

									
										src/search.h
									
		+1
		
												View File
												
				@@ -52,6 +52,7 @@ struct Stack {

				  bool inCheck;

				  bool ttPv;

				  bool ttHit;

				  int doubleExtensions;

				};