From: xoto10 <buylow001@gmail.com>
Date: Mon, 9 Dec 2019 21:38:57 +0000 (+0000)
Subject: TrappedRook value and King positional tables
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=3ef0c3c34a00e6b13d6c96d8c2f0d8d7a6cc25a6;hp=764b9adda6cf59719b5c9c8a75d2a2e696395709

TrappedRook value and King positional tables

Small tweak to increase the TrappedRook penalty. Nice idea by Alain Savard!

STC
LLR: 2.96 (-2.94,2.94) [-1.50,4.50]
Total: 36977 W: 8212 L: 7993 D: 20772
https://tests.stockfishchess.org/tests/view/5dee1c1e3cff9a249bb9e46d

LTC
LLR: 2.95 (-2.94,2.94) [0.00,3.50]
Total: 36395 W: 6070 L: 5795 D: 24530
https://tests.stockfishchess.org/tests/view/5dee90153cff9a249bb9e479

Closes https://github.com/official-stockfish/Stockfish/pull/2447

Bench: 5176990

-------------------------

Comments by Alain Savard:

For the record, the idea was to run an experimental tuning with disabled
castling in the hope to get more hits on the TrappedRook and the king in
the c1- f1-f2-c2 area
http://tests.stockfishchess.org/tests/view/5dec57be51219d7befdc76e1

A first interpretation of that tuning was green STC (0, 4) and yellow LTC (0, 4):
http://tests.stockfishchess.org/tests/view/5ded04bc51219d7befdc773a
http://tests.stockfishchess.org/tests/view/5ded1e7a51219d7befdc7760

Thank you @xoto for trying this. Indeed, because the tuned Kc2 and Kf2 values
were quite different, it was a good idea to try something more neutral.
---

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 20d1059e..e7d30825 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -145,7 +145,7 @@ namespace {
   constexpr Score ThreatByKing       = S( 24, 89);
   constexpr Score ThreatByPawnPush   = S( 48, 39);
   constexpr Score ThreatBySafePawn   = S(173, 94);
-  constexpr Score TrappedRook        = S( 47,  4);
+  constexpr Score TrappedRook        = S( 52, 10);
   constexpr Score WeakQueen          = S( 49, 15);
 
 #undef S
diff --git a/src/psqt.cpp b/src/psqt.cpp
index 60d17ad2..c11dc5ba 100644
--- a/src/psqt.cpp
+++ b/src/psqt.cpp
@@ -79,8 +79,8 @@ constexpr Score Bonus[][RANK_NB][int(FILE_NB) / 2] = {
    { S(-2,-75), S(-2,-52), S( 1,-43), S(-2,-36) }
   },
   { // King
-   { S(271,  1), S(327, 45), S(270, 85), S(192, 76) },
-   { S(278, 53), S(303,100), S(230,133), S(174,135) },
+   { S(271,  1), S(327, 45), S(271, 85), S(198, 76) },
+   { S(278, 53), S(303,100), S(234,133), S(179,135) },
    { S(195, 88), S(258,130), S(169,169), S(120,175) },
    { S(164,103), S(190,156), S(138,172), S( 98,172) },
    { S(154, 96), S(179,166), S(105,199), S( 70,199) },