Simplify endgame factor for opposite colored bishops
authorSFisGOD <jonathandumale@gmail.com>
Wed, 20 Nov 2019 19:31:23 +0000 (03:31 +0800)
committerStéphane Nicolet <cassio@free.fr>
Sat, 23 Nov 2019 23:23:06 +0000 (00:23 +0100)
Stockfish is continually improving. Patches that gain elo in the past may
no longer be needed as stockfish improved elsewhere. This patch removes
passed pawns count dependence in opposite colored bishops scale factor.
We used the mean of passed count pawns (~1.4) to compensate, and changed
the base value from 16 to 22.

Passed STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 57879 W: 12657 L: 12607 D: 32615
http://tests.stockfishchess.org/tests/view/5dd1644f42928ff08153dc1e

Passed LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 121648 W: 19622 L: 19659 D: 82367
http://tests.stockfishchess.org/tests/view/5dd24572ccb823d41d4b47bb

Closes https://github.com/official-stockfish/Stockfish/pull/2419

Bench: 5067864

src/evaluate.cpp

index 7760f70..eb5719b 100644 (file)
@@ -748,7 +748,7 @@ namespace {
     {
         if (   pos.opposite_bishops()
             && pos.non_pawn_material() == 2 * BishopValueMg)
-            sf = 16 + 4 * pe->passed_count();
+            sf = 22 ;
         else
             sf = std::min(sf, 36 + (pos.opposite_bishops() ? 2 : 7) * pos.count<PAWN>(strongSide));