Tweak of SEE pruning condition

Vizvezdenec · snicolet · commit acdda38b9336 · 2019-07-25T09:16:53.000+02:00
passed STC http://tests.stockfishchess.org/tests/view/5d386bda0ebc5925cf0ef49a LLR: 2.95 (-2.94,2.94) [0.50,4.50] Total: 56874 W: 12820 L: 12373 D: 31681 passed LTC http://tests.stockfishchess.org/tests/view/5d38873a0ebc5925cf0ef86e LLR: 2.95 (-2.94,2.94) [0.00,3.50] Total: 43512 W: 7547 L: 7247 D: 28718 Additional thanks to @locutus2 , @miguel-l and @xoto10 for fruitful discussion. There may be some more elo there since this tweak was the first one and numbers are more or less arbitrary. Closes #2256 Bench 3935523
diff --git a/src/search.cpp b/src/search.cpp
@@ -1041,7 +1041,7 @@ namespace {
                   continue;
 
               // Prune moves with negative SEE (~10 Elo)
-              if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth)))
+              if (!pos.see_ge(move, Value(-(31 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
                   continue;
           }
           else if (  (!givesCheck || !extension)

Original file line number	Diff line number	Diff line change
`@@ -1041,7 +1041,7 @@ namespace {`
`1041`	`1041`	`continue;`
`1042`	`1042`
`1043`	`1043`	`// Prune moves with negative SEE (~10 Elo)`
`1044`		`- if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth)))`
	`1044`	`+ if (!pos.see_ge(move, Value(-(31 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))`
`1045`	`1045`	`continue;`
`1046`	`1046`	`}`
`1047`	`1047`	`else if ( (!givesCheck \|\| !extension)`