Use single value for KingProtector.

After some recent big tuning session, the values for King Protector were
simplified to only be used on minor pieces. This patch tries to further
simplify by just using a single value, since current S(6,5) and S(5,6)
are close to each other. The value S(6,6) ended up passing, although
S(5,5) was also tried and failed STC.

STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 14261 W: 3288 L: 3151 D: 7822
http://tests.stockfishchess.org/tests/view/5b4ccdf50ebc5902bdb77f65

LTC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 19606 W: 3396 L: 3273 D: 12937
http://tests.stockfishchess.org/tests/view/5b4ce4280ebc5902bdb7803b

Bench: 5448998

diff --git a/AUTHORS b/AUTHORS
index b396db817e07b975632016d7ddc355523bba1dbc..029109acd512a8ad29fbde9b8fd5b7cd932fc64a 100644 (file)
--- a/AUTHORS
+++ b/AUTHORS
@@ -82,6 +82,7 @@ Mark Tenzer (31m059)
 Michael Byrne (MichaelB7)
 Michael Stembera (mstembera)
 Michel Van den Bergh (vdbergh)
+Miguel Lahoz (miguel-l)
 Mikael Bäckman (mbootsector)
 Mike Whiteley (protonspring)
 Miroslav Fontán (Hexik)
@@ -118,4 +119,3 @@ Tom Vijlbrief (tomtor)
 Torsten Franz (torfranz)
 Uri Blass (uriblass)
 Vince Negri
-xoroshiro

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 2fb0e55a9d47b08ed61fa7319aca386200140390..b1e94ab7cf86e38a5765fbd465709e3cbfecdcfd 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -154,9 +154,6 @@ namespace {
   // PassedDanger[Rank] contains a term to weight the passed score
   constexpr int PassedDanger[RANK_NB] = { 0, 0, 0, 3, 7, 11, 20 };
 
-  // KingProtector[knight/bishop] contains a penalty according to distance from king
-  constexpr Score KingProtector[] = { S(5, 6), S(6, 5) };
-
   // Assorted bonuses and penalties
   constexpr Score BishopPawns        = S(  3,  7);
   constexpr Score CloseEnemies       = S(  6,  0);
@@ -164,6 +161,7 @@ namespace {
   constexpr Score CorneredBishop     = S( 50, 50);
   constexpr Score Hanging            = S( 52, 30);
   constexpr Score HinderPassedPawn   = S(  4,  0);
+  constexpr Score KingProtector      = S(  6,  6);
   constexpr Score KnightOnQueen      = S( 21, 11);
   constexpr Score LongDiagonalBishop = S( 22,  0);
   constexpr Score MinorBehindPawn    = S( 16,  0);
@@ -342,7 +340,7 @@ namespace {
                 score += MinorBehindPawn;
 
             // Penalty if the piece is far from the king
-            score -= KingProtector[Pt == BISHOP] * distance(s, pos.square<KING>(Us));
+            score -= KingProtector * distance(s, pos.square<KING>(Us));
 
             if (Pt == BISHOP)
             {