Tweak reductions for captures/promotions

locutus2 · snicolet · commit 7150183d07a4 · 2020-01-13T12:09:23.000+01:00
From the third move reduce captures and promotions more if remaining depth is low. STC: LLR: 2.94 (-2.94,2.94) {-1.00,3.00} Total: 25218 W: 5008 L: 4837 D: 15373 Ptnml(0-2): 439, 2950, 5717, 3001, 499 http://tests.stockfishchess.org/tests/view/5e1b33abd12216a2857e6359 LTC: LLR: 2.95 (-2.94,2.94) {0.00,2.00} Total: 35491 W: 4760 L: 4524 D: 26207 Ptnml(0-2): 264, 3288, 10413, 3460, 294 http://tests.stockfishchess.org/tests/view/5e1b88d5d12216a2857e6385 Closes #2488 Bench: 4979757
diff --git a/src/search.cpp b/src/search.cpp
@@ -1186,6 +1186,10 @@ namespace {
               r -= ss->statScore / 16384;
           }
 
+          // Increase reduction for captures/promotions if late move and at low depth
+          else if (depth < 8 && moveCount > 2)
+              r++;
+
           Depth d = clamp(newDepth - r, 1, newDepth);
 
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);

Original file line number	Diff line number	Diff line change
`@@ -1186,6 +1186,10 @@ namespace {`
`1186`	`1186`	`r -= ss->statScore / 16384;`
`1187`	`1187`	`}`
`1188`	`1188`
	`1189`	`+ // Increase reduction for captures/promotions if late move and at low depth`
	`1190`	`+ else if (depth < 8 && moveCount > 2)`
	`1191`	`+ r++;`
	`1192`	`+`
`1189`	`1193`	`Depth d = clamp(newDepth - r, 1, newDepth);`
`1190`	`1194`
`1191`	`1195`	`value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);`