Tuned safe checks and minor piece king protectors

linrock · vondele · commit 7f8166db8912 · 2020-05-02T17:26:51.000+02:00
A combination of terms related to king safety one tuned safe check weights, the other tuned knight and bishop king protector weights separately with some compensation in the high outpost bonuses given to the minor pieces. passed STC LLR: 2.95 (-2.94,2.94) {-0.50,1.50} Total: 39892 W: 7594 L: 7350 D: 24948 Ptnml(0-2): 643, 4559, 9314, 4771, 659 https://tests.stockfishchess.org/tests/view/5ea49635b908f6dd28f34b82 passed LTC LLR: 2.94 (-2.94,2.94) {0.25,1.75} Total: 104934 W: 13300 L: 12834 D: 78800 Ptnml(0-2): 697, 9571, 31514, 9939, 746 https://tests.stockfishchess.org/tests/view/5ea4abf6b908f6dd28f34bcb closes #2649 Bench 4800754
diff --git a/AUTHORS b/AUTHORS
@@ -42,6 +42,7 @@ Eelco de Groot (KingDefender)
 Elvin Liu (solarlight2)
 erbsenzaehler
 Ernesto Gatti
+Linmiao Xu (linrock)
 Fabian Beuke (madnight)
 Fabian Fichter (ianfab)
 fanon
diff --git a/src/evaluate.cpp b/src/evaluate.cpp
@@ -81,10 +81,10 @@ namespace {
   constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 81, 52, 44, 10 };
 
   // Penalties for enemy's safe checks
-  constexpr int QueenSafeCheck  = 780;
-  constexpr int RookSafeCheck   = 1078;
-  constexpr int BishopSafeCheck = 635;
-  constexpr int KnightSafeCheck = 790;
+  constexpr int QueenSafeCheck  = 772;
+  constexpr int RookSafeCheck   = 1084;
+  constexpr int BishopSafeCheck = 645;
+  constexpr int KnightSafeCheck = 792;
 
 #define S(mg, eg) make_score(mg, eg)
 
@@ -131,11 +131,14 @@ namespace {
   constexpr Score CorneredBishop      = S( 50, 50);
   constexpr Score FlankAttacks        = S(  8,  0);
   constexpr Score Hanging             = S( 69, 36);
-  constexpr Score KingProtector       = S(  7,  8);
+  constexpr Score BishopKingProtector = S(  6,  9);
+  constexpr Score KnightKingProtector = S(  8,  9);
   constexpr Score KnightOnQueen       = S( 16, 11);
   constexpr Score LongDiagonalBishop  = S( 45,  0);
   constexpr Score MinorBehindPawn     = S( 18,  3);
-  constexpr Score Outpost             = S( 30, 21);
+  constexpr Score KnightOutpost       = S( 56, 36);
+  constexpr Score BishopOutpost       = S( 30, 23);
+  constexpr Score ReachableOutpost    = S( 31, 22);
   constexpr Score PassedFile          = S( 11,  8);
   constexpr Score PawnlessFlank       = S( 17, 95);
   constexpr Score RestrictedPiece     = S(  7,  7);
@@ -293,17 +296,17 @@ namespace {
             // Bonus if piece is on an outpost square or can reach one
             bb = OutpostRanks & attackedBy[Us][PAWN] & ~pe->pawn_attacks_span(Them);
             if (bb & s)
-                score += Outpost * (Pt == KNIGHT ? 2 : 1);
-
+                score += (Pt == KNIGHT) ? KnightOutpost : BishopOutpost;
             else if (Pt == KNIGHT && bb & b & ~pos.pieces(Us))
-                score += Outpost;
+                score += ReachableOutpost;
 
             // Bonus for a knight or bishop shielded by pawn
             if (shift<Down>(pos.pieces(PAWN)) & s)
                 score += MinorBehindPawn;
 
             // Penalty if the piece is far from the king
-            score -= KingProtector * distance(pos.square<KING>(Us), s);
+            score -= (Pt == KNIGHT ? KnightKingProtector
+                                   : BishopKingProtector) * distance(pos.square<KING>(Us), s);
 
             if (Pt == BISHOP)
             {
@@ -399,7 +402,7 @@ namespace {
     // Enemy rooks checks
     rookChecks = b1 & safe & attackedBy[Them][ROOK];
     if (rookChecks)
-        kingDanger += more_than_one(rookChecks) ? RookSafeCheck * 3/2
+        kingDanger += more_than_one(rookChecks) ? RookSafeCheck * 175/100
                                                 : RookSafeCheck;
     else
         unsafeChecks |= b1 & attackedBy[Them][ROOK];
@@ -412,7 +415,7 @@ namespace {
                  & ~attackedBy[Us][QUEEN]
                  & ~rookChecks;
     if (queenChecks)
-        kingDanger += more_than_one(queenChecks) ? QueenSafeCheck * 3/2
+        kingDanger += more_than_one(queenChecks) ? QueenSafeCheck * 145/100
                                                  : QueenSafeCheck;
 
     // Enemy bishops checks: we count them only if they are from squares from
@@ -430,7 +433,7 @@ namespace {
     // Enemy knights checks
     knightChecks = pos.attacks_from<KNIGHT>(ksq) & attackedBy[Them][KNIGHT];
     if (knightChecks & safe)
-        kingDanger += more_than_one(knightChecks & safe) ? KnightSafeCheck * 3/2
+        kingDanger += more_than_one(knightChecks & safe) ? KnightSafeCheck * 162/100
                                                          : KnightSafeCheck;
     else
         unsafeChecks |= knightChecks;
