From: Fabian Fichter <ianfab@users.noreply.github.com>
Date: Tue, 22 Dec 2020 14:43:51 +0000 (+0100)
Subject: Simplify space evaluation for drop variants
X-Git-Url: http://winboard.nl/cgi-bin?a=commitdiff_plain;h=89dbe3c429405254d4e7f02f0aa22be9890135d8;p=fairystockfish.git

Simplify space evaluation for drop variants

crazyhouse STC
LLR: 2.98 (-2.94,2.94) [-10.00,5.00]
Total: 3579 W: 1749 L: 1708 D: 122
http://www.variantfishtest.org:6543/tests/view/5fdf73c16e23db221d9e95f5

crazyhouse LTC
LLR: 2.95 (-2.94,2.94) [-10.00,5.00]
Total: 945 W: 484 L: 425 D: 36
http://www.variantfishtest.org:6543/tests/view/5fe1b6c56e23db221d9e9653

shogi STC
LLR: -2.98 (-2.94,2.94) [-10.00,5.00]
Total: 4773 W: 2324 L: 2427 D: 22
http://www.variantfishtest.org:6543/tests/view/5fdf73d36e23db221d9e95f8

shogi LTC
LLR: 2.97 (-2.94,2.94) [-10.00,5.00]
Total: 3545 W: 1785 L: 1742 D: 18
http://www.variantfishtest.org:6543/tests/view/5fe1b6b06e23db221d9e9651
---

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 539e392..9f22d43 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -1074,7 +1074,7 @@ namespace {
     bool pawnsOnly = !(pos.pieces(Us) ^ pos.pieces(Us, PAWN));
 
     // Early exit if, for example, both queens or 6 minor pieces have been exchanged
-    if (pos.non_pawn_material() < SpaceThreshold && !pos.captures_to_hand() && !pawnsOnly && pos.double_step_enabled())
+    if (pos.non_pawn_material() < SpaceThreshold && !pawnsOnly && pos.double_step_enabled())
         return SCORE_ZERO;
 
     constexpr Color Them     = ~Us;