kate/BadFish
1
0
Fork 0
mirror of https://github.com/sockspls/badfish synced 2025-05-01 09:13:08 +00:00
Code Issues Releases Wiki Activity

Fix doubled pawns asymmetry

Browse source 
When evaluating double pawns we use always
lsb() to extract the frontmost square.

This breaks evaluation color symmetry as is
possible to verify with an instrumented evaluate()

  Value evaluate(const Position& pos) {

    Value v = do_evaluate<false>(pos);
    Position p = pos;
    p.flip();
    assert(v == do_evaluate<false>(p));
    return v;
  }

Passed no regression test:

STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 21035 W: 4244 L: 4122 D: 12669

LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 39839 W: 6662 L: 6572 D: 26605

bench: 8255966
This commit is contained in:
Marco Costalba 2014-11-20 12:13:00 +01:00
parent 79232be02a
commit 84408e5cd6
1 changed files with 1 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
src/pawns.cpp
View file

@ -165,7 +165,7 @@ namespace {
value -= UnsupportedPawnPenalty;
if (doubled)
value -= Doubled[f] / distance<Rank>(s, Square(lsb(doubled)));
value -= Doubled[f] / distance<Rank>(s, frontmost_sq(Us, doubled));
if (backward)
value -= Backward[opposed][f];