Tweak isolated pawn penalty for losing chess variants

giveaway STC
LLR: 2.98 (-2.94,2.94) [0.00,10.00]
Total: 1699 W: 626 L: 526 D: 547
http://35.161.250.236:6543/tests/view/5c1954786e23db24728955bb

losers STC
LLR: 2.97 (-2.94,2.94) [0.00,10.00]
Total: 4610 W: 2045 L: 1890 D: 675
http://35.161.250.236:6543/tests/view/5c1954b76e23db24728955be

diff --git a/src/pawns.cpp b/src/pawns.cpp
index bea3e55..04b727b 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -139,7 +139,7 @@ namespace {
             score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s, pos.max_rank())];
 
         else if (!neighbours)
-            score -= Isolated, e->weakUnopposed[Us] += !opposed;
+            score -= Isolated * (1 + 2 * pos.must_capture()), e->weakUnopposed[Us] += !opposed;
 
         else if (backward)
             score -= Backward, e->weakUnopposed[Us] += !opposed;