Simplify RookOnPawn

Remove the RookOnPawn logic (for rook on rank 5 and above aligning with pawns
on same row or file) which was overlapping with a few other parameters.

Inspired by @31m059 interesting result hinting that a direct attack on pawns
instead of PseudoAttacks might work.
http://tests.stockfishchess.org/tests/view/5d89a7c70ebc595091801b8d

After a few attempts by me and @31m059, and some long STC greens but red LTC,
as a proof of concept I first tried a local SPSA at VSTC trying to tune related
rook psqt rows, and mainly some rook related stuff in evaluate.cpp.
Result was STC green, but still red LTC,

Finally a 100M fishtest SPSA at LTC proved successful both at STC and LTC.

All this was possible with the awesome fishtest contributors.
At some point, I had 850 workers on the last test !

Run as a simplification

STC
http://tests.stockfishchess.org/tests/view/5d8d68f40ebc590f3beaf171
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 7399 W: 1693 L: 1543 D: 4163

LTC
http://tests.stockfishchess.org/tests/view/5d8d70270ebc590f3beaf63c
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 41617 W: 6981 L: 6894 D: 27742

Closes https://github.com/official-stockfish/Stockfish/pull/2329

bench: 4037914

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index f37820afcef975b2f5bb326b30bbe16588d4b6ea..880aa1375badc42ceba8f89bf78541ad5e84f31d 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -78,7 +78,7 @@ namespace {
   constexpr Value SpaceThreshold = Value(12222);
 
   // KingAttackWeights[PieceType] contains king attack weights by piece type
-  constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 77, 55, 44, 10 };
+  constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 81, 52, 44, 10 };
 
   // Penalties for enemy's safe checks
   constexpr int QueenSafeCheck  = 780;
@@ -108,17 +108,17 @@ namespace {
 
   // RookOnFile[semiopen/open] contains bonuses for each rook when there is
   // no (friendly) pawn on the rook file.
-  constexpr Score RookOnFile[] = { S(18, 7), S(44, 20) };
+  constexpr Score RookOnFile[] = { S(21, 4), S(47, 25) };
 
   // ThreatByMinor/ByRook[attacked PieceType] contains bonuses according to
   // which piece type attacks which one. Attacks on lesser pieces which are
   // pawn-defended are not considered.
   constexpr Score ThreatByMinor[PIECE_TYPE_NB] = {
-    S(0, 0), S(0, 31), S(39, 42), S(57, 44), S(68, 112), S(62, 120)
+    S(0, 0), S(6, 28), S(39, 42), S(57, 44), S(68, 112), S(62, 120)
   };
 
   constexpr Score ThreatByRook[PIECE_TYPE_NB] = {
-    S(0, 0), S(0, 24), S(38, 71), S(38, 61), S(0, 38), S(51, 38)
+    S(0, 0), S(3, 44), S(38, 71), S(38, 61), S(0, 38), S(51, 38)
   };
 
   // PassedRank[Rank] contains a bonus according to the rank of a passed pawn
@@ -139,8 +139,7 @@ namespace {
   constexpr Score PassedFile         = S( 11,  8);
   constexpr Score PawnlessFlank      = S( 17, 95);
   constexpr Score RestrictedPiece    = S(  7,  7);
-  constexpr Score RookOnPawn         = S( 10, 32);
-  constexpr Score RookOnQueenFile    = S( 11,  4);
+  constexpr Score RookOnQueenFile    = S(  7,  6);
   constexpr Score SliderOnQueen      = S( 59, 18);
   constexpr Score ThreatByKing       = S( 24, 89);
   constexpr Score ThreatByPawnPush   = S( 48, 39);
@@ -343,10 +342,6 @@ namespace {
 
         if (Pt == ROOK)
         {
-            // Bonus for aligning rook with enemy pawns on the same rank/file
-            if (relative_rank(Us, s) >= RANK_5)
-                score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
-
             // Bonus for rook on the same file as a queen
             if (file_bb(s) & pos.pieces(QUEEN))
                 score += RookOnQueenFile;

diff --git a/src/psqt.cpp b/src/psqt.cpp
index 83d11cf1c1a8fe4e923e86eccf31fc2771a50733..655eb993663d127b2ae5b987265b856094c62bd4 100644 (file)
--- a/src/psqt.cpp
+++ b/src/psqt.cpp
@@ -59,14 +59,14 @@ constexpr Score Bonus[][RANK_NB][int(FILE_NB) / 2] = {
    { S(-48,-51), S( -3,-40), S(-12,-39), S(-25,-20) }
   },
   { // Rook
-   { S(-24, -2), S(-13,-6), S(-7, -3), S( 2,-2) },
-   { S(-18,-10), S(-10,-7), S(-5,  1), S( 9, 0) },
-   { S(-21, 10), S( -7,-4), S( 3,  2), S( 7,-2) },
-   { S(-13, -5), S( -5, 2), S(-4, -8), S(-6, 8) },
-   { S(-24, -8), S(-12, 5), S(-1,  4), S( 6,-9) },
-   { S(-24,  3), S( -4,-2), S( 4,-10), S(10, 7) },
-   { S( -8,  1), S(  6, 2), S(10, 17), S(12,-8) },
-   { S(-22, 12), S(-24,-6), S(-6, 13), S( 4, 7) }
+   { S(-31, -9), S(-20,-13), S(-14,-10), S(-5, -9) },
+   { S(-21,-12), S(-13, -9), S( -8, -1), S( 6, -2) },
+   { S(-25,  6), S(-11, -8), S( -1, -2), S( 3, -6) },
+   { S(-13, -6), S( -5,  1), S( -4, -9), S(-6,  7) },
+   { S(-27, -5), S(-15,  8), S( -4,  7), S( 3, -6) },
+   { S(-22,  6), S( -2,  1), S(  6, -7), S(12, 10) },
+   { S( -2,  4), S( 12,  5), S( 16, 20), S(18, -5) },
+   { S(-17, 18), S(-19,  0), S( -1, 19), S( 9, 13) }
   },
   { // Queen
    { S( 3,-69), S(-5,-57), S(-5,-47), S( 4,-26) },