Simplify eval >= beta condition from NMP

aronpetko · vondele · commit a516b517d374 · 2025-07-24T10:38:13.000+02:00
It seems that now only checking if static eval is above beta by some margin is all that's necessary. Passed Non-Regression STC LLR: 2.93 (-2.94,2.94) <-1.75,0.25> Total: 227264 W: 58430 L: 58421 D: 110413 Ptnml(0-2): 532, 26559, 59454, 26542, 545 https://tests.stockfishchess.org/tests/view/68763a77432ca24f6388c766 Passed Non-Regression LTC LLR: 2.94 (-2.94,2.94) <-1.75,0.25> Total: 72048 W: 18622 L: 18455 D: 34971 Ptnml(0-2): 26, 7775, 20272, 7908, 43 https://tests.stockfishchess.org/tests/view/687c9f2b6e17e7fa3939b0c5 closes #6175 Bench: 2759840
diff --git a/AUTHORS b/AUTHORS
@@ -31,6 +31,7 @@ Andy Duplain
 Antoine Champion (antoinechampion)
 Aram Tumanian (atumanian)
 Arjun Temurnikar
+Aron Petkovski (fury)
 Artem Solopiy (EntityFX)
 Auguste Pop
 Balazs Szilagyi
diff --git a/src/search.cpp b/src/search.cpp
@@ -848,12 +848,10 @@ Value Search::Worker::search(
     }
 
     // Step 9. Null move search with verification search
-    if (cutNode && (ss - 1)->currentMove != Move::null() && eval >= beta
+    if (cutNode && (ss - 1)->currentMove != Move::null()
         && ss->staticEval >= beta - 19 * depth + 389 && !excludedMove && pos.non_pawn_material(us)
         && ss->ply >= nmpMinPly && !is_loss(beta))
     {
-        assert(eval - beta >= 0);
-
         // Null move dynamic reduction based on depth
         Depth R = 7 + depth / 3;
 

Original file line number	Diff line number	Diff line change
`@@ -848,12 +848,10 @@ Value Search::Worker::search(`
`848`	`848`	`}`
`849`	`849`
`850`	`850`	`// Step 9. Null move search with verification search`
`851`		`- if (cutNode && (ss - 1)->currentMove != Move::null() && eval >= beta`
	`851`	`+ if (cutNode && (ss - 1)->currentMove != Move::null()`
`852`	`852`	`&& ss->staticEval >= beta - 19 * depth + 389 && !excludedMove && pos.non_pawn_material(us)`
`853`	`853`	`&& ss->ply >= nmpMinPly && !is_loss(beta))`
`854`	`854`	`{`
`855`		`- assert(eval - beta >= 0);`
`856`		`-`
`857`	`855`	`// Null move dynamic reduction based on depth`
`858`	`856`	`Depth R = 7 + depth / 3;`
`859`	`857`