Encourage rook lift to third rank

xoto10 · snicolet · commit defa1ccaa9c1 · 2019-09-23T09:50:34.000+02:00
This change to the Rook psqt encourages rook lifts to the third rank on the two center files. STC 10+0.1 th 1 : LLR: 2.96 (-2.94,2.94) [0.00,4.00] Total: 40654 W: 9028 L: 8704 D: 22922 http://tests.stockfishchess.org/tests/view/5d885da60ebc5906dd3e9fcd LTC 60+0.6 th 1 : LLR: 2.96 (-2.94,2.94) [0.00,4.00] Total: 56963 W: 9530 L: 9196 D: 38237 http://tests.stockfishchess.org/tests/view/5d88618c0ebc5906dd3ea45f Thanks to @snicolet for mentioning that Komodo does this a lot and Stockfish doesn't, which gave me the idea for this patch, and to @noobpwnftw for providing cores to fishtest which allowed very quick testing. Future work: perhaps this can be refined somehow to encourage this on other files, my attempts have failed. Closes #2322 Bench: 3950249
diff --git a/src/psqt.cpp b/src/psqt.cpp
@@ -61,7 +61,7 @@ constexpr Score Bonus[][RANK_NB][int(FILE_NB) / 2] = {
   { // 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(-1,-2) },
+   { 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) },
