From: Fabian Fichter <ianfab@users.noreply.github.com>
Date: Fri, 18 Dec 2020 12:51:24 +0000 (+0100)
Subject: Tweak horde breakthrough bonus
X-Git-Url: http://winboard.nl/cgi-bin?a=commitdiff_plain;h=9b7d00b3a89ab43d8563018405777d0ffd9fbcdd;p=fairystockfish.git

Tweak horde breakthrough bonus

horde STC
LLR: 2.97 (-2.94,2.94) [0.00,10.00]
Total: 1952 W: 1029 L: 899 D: 24
http://www.variantfishtest.org:6543/tests/view/5fdc72e46e23db221d9e9586

horde LTC
LLR: 2.95 (-2.94,2.94) [0.00,10.00]
Total: 2054 W: 1083 L: 952 D: 19
http://www.variantfishtest.org:6543/tests/view/5fdc785c6e23db221d9e9589
---

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 7b129a2..d039ec3 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -1189,7 +1189,7 @@ namespace {
                     dist = attackedBy[Us][QUEEN] & breakthroughs ? 0 : 1;
                 else for (File f = FILE_A; f <= pos.max_file(); ++f)
                     dist = std::min(dist, popcount(pos.pieces(PAWN) & file_bb(f)));
-                score += make_score(70, 70) * pos.count<PAWN>(Them) / (1 + dist * (dist + 1)) / (pos.pieces(Us, QUEEN) ? 2 : 4);
+                score += make_score(70, 70) * pos.count<PAWN>(Them) / (1 + dist * dist) / (pos.pieces(Us, QUEEN) ? 2 : 4);
             }
     }