Reduce less for positions without tt move

Vizvezdenec · Disservin · commit e852d9880a6d · 2025-02-04T21:37:11.000+01:00
Continuation of work on scaling. In line with previous scaling patches this one massively reduces reduction for moves that don't go thru lmr for position without a tt move. Passed VVLTC with STC bounds: https://tests.stockfishchess.org/tests/view/679fd2450774dfd78deb12b2 LLR: 2.94 (-2.94,2.94) <0.00,2.00> Total: 74718 W: 19354 L: 19042 D: 36322 Ptnml(0-2): 5, 6724, 23595, 7024, 11 Passed VVLTC with LTC bounds: https://tests.stockfishchess.org/tests/view/67a009930774dfd78deb2346 LLR: 2.94 (-2.94,2.94) <0.50,2.50> Total: 82638 W: 21587 L: 21212 D: 39839 Ptnml(0-2): 15, 7476, 25953, 7869, 6 closes #5860 Bench: 2887850
diff --git a/src/search.cpp b/src/search.cpp
@@ -1241,7 +1241,7 @@ Value Search::Worker::search(
         {
             // Increase reduction if ttMove is not present
             if (!ttData.move)
-                r += 2117;
+                r += 1111;
 
             // Note that if expected reduction is high, we reduce search depth here
             value = -search<NonPV>(pos, ss + 1, -(alpha + 1), -alpha,

Original file line number	Diff line number	Diff line change
`@@ -1241,7 +1241,7 @@ Value Search::Worker::search(`
`1241`	`1241`	`{`
`1242`	`1242`	`// Increase reduction if ttMove is not present`
`1243`	`1243`	`if (!ttData.move)`
`1244`		`- r += 2117;`
	`1244`	`+ r += 1111;`
`1245`	`1245`
`1246`	`1246`	`// Note that if expected reduction is high, we reduce search depth here`
`1247`	`1247`	`value = -search<NonPV>(pos, ss + 1, -(alpha + 1), -alpha,`