From: Joost VandeVondele <Joost.VandeVondele@gmail.com>
Date: Thu, 22 Dec 2016 15:02:32 +0000 (+0100)
Subject: Simplify threshold handling for probcut. (#936)
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=1ceaea701baaa79f378b0842ff0fb5d2a1f53ef7;ds=sidebyside

Simplify threshold handling for probcut. (#936)

Just use greater equal as this is what see_ge does now.

passed STC
LLR: 2.94 (-2.94,2.94) [-3.00,1.00]
Total: 226506 W: 39755 L: 39978 D: 146773

passed LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 138483 W: 17450 L: 17479 D: 103554

Bench: 5212921
---

diff --git a/src/movepick.cpp b/src/movepick.cpp
index c187c3ad..abb753ba 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -111,11 +111,11 @@ MovePicker::MovePicker(const Position& p, Move ttm, Value th)
 
   stage = PROBCUT;
 
-  // In ProbCut we generate captures with SEE higher than the given threshold
+  // In ProbCut we generate captures with SEE higher than or equal to the given threshold
   ttMove =   ttm
           && pos.pseudo_legal(ttm)
           && pos.capture(ttm)
-          && pos.see_ge(ttm, threshold + 1)? ttm : MOVE_NONE;
+          && pos.see_ge(ttm, threshold)? ttm : MOVE_NONE;
 
   stage += (ttMove == MOVE_NONE);
 }
@@ -294,7 +294,7 @@ Move MovePicker::next_move() {
       {
           move = pick_best(cur++, endMoves);
           if (   move != ttMove
-              && pos.see_ge(move, threshold + 1))
+              && pos.see_ge(move, threshold))
               return move;
       }
       break;