From a95d545585bb18380e72ae54b2c150b9d47a270b Mon Sep 17 00:00:00 2001
From: Bruno Dutra <brunocodutra@gmail.com>
Date: Thu, 21 Nov 2024 17:12:15 +0100
Subject: [PATCH] disable reverse futility pruning at PV nodes

---
 lib/search/engine.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/search/engine.rs b/lib/search/engine.rs
index e01654b4..6190c028 100644
--- a/lib/search/engine.rs
+++ b/lib/search/engine.rs
@@ -189,7 +189,7 @@ impl Engine {
 
         if alpha >= beta || ply >= Ply::MAX {
             return Ok(pv);
-        } else if pv.score() - self.rfp(depth, ply) >= beta {
+        } else if !is_pv && pv.score() - self.rfp(depth, ply) >= beta {
             #[cfg(not(test))]
             // The reverse futility pruning heuristic is not exact.
             return Ok(pv);