Simplify condition for ProbCut move count pruning
authorJerry Donald Watson <j1.donald1@gmail.com>
Tue, 13 Mar 2018 09:15:42 +0000 (09:15 +0000)
committerStéphane Nicolet <cassio@free.fr>
Tue, 13 Mar 2018 22:32:45 +0000 (23:32 +0100)
commitb605103a34be5bea7815ab3f6d4a21d487d0182b
tree7918fd4c82b9bb93b203db45d247229b38d49af9
parentc5f6bd517c68e16c3ead7892e1d83a6b1bb89b69
Simplify condition for ProbCut move count pruning

We retire depth-dependence in ProbCut move count pruning,
the move count limit condition is now : "probCutCount < 3"

STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 33895 W: 6995 L: 6897 D: 20003
http://tests.stockfishchess.org/tests/view/5aa6eaba0ebc59029781009d

LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 28959 W: 4441 L: 4333 D: 20185
http://tests.stockfishchess.org/tests/view/5aa73dfa0ebc5902978100be

Ideas for future work:

• Is a flat move count limit in ProbCut ideal? Depth dependence, or
  dependence on some other variable, could possibly be reintroduced.

• The move count limit 3 is untuned and a better value may exist.

Closes https://github.com/official-stockfish/Stockfish/pull/1486

Bench: 5741807
src/search.cpp