From 5ec63eb6b6f43cbd4e25b8f8b97bc8980dbbabef Mon Sep 17 00:00:00 2001
From: Michel Van den Bergh <michel.vandenbergh@uhasselt.be>
Date: Tue, 13 May 2014 22:33:41 +0200
Subject: [PATCH 1/1] Drop to qsearch at low depth in razoring

If razoring conditions are satisfied and
depth is low, then directly drop in qsearch.

Passed both STC
LLR: 2.98 (-2.94,2.94) [-1.50,4.50]
Total: 12914 W: 2345 L: 2208 D: 8361

And LTC
LLR: 2.95 (-2.94,2.94) [0.00,6.00]
Total: 50600 W: 7548 L: 7230 D: 35822

bench: 8739659
---
 src/search.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/search.cpp b/src/search.cpp
index 3d755586..aa63fcb4 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -582,6 +582,10 @@ namespace {
         &&  abs(beta) < VALUE_MATE_IN_MAX_PLY
         && !pos.pawn_on_7th(pos.side_to_move()))
     {
+        if (   depth <= ONE_PLY
+            && eval + razor_margin(3 * ONE_PLY) <= alpha)
+            return qsearch<NonPV, false>(pos, ss, alpha, beta, DEPTH_ZERO);
+
         Value ralpha = alpha - razor_margin(depth);
         Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1, DEPTH_ZERO);
         if (v <= ralpha)
-- 
2.39.2