...apparently it wasn't doing much anymore. inspired by rufish's recent attempts to improve this.
passed STC:
https://tests.stockfishchess.org/tests/view/
62abca2cd89eb6cf1e072c04
LLR: 2.95 (-2.94,2.94) <-2.25,0.25>
Total: 85576 W: 22766 L: 22683 D: 40127
Ptnml(0-2): 362, 9607, 22741, 9742, 336
passed LTC:
https://tests.stockfishchess.org/tests/view/
62ac90ffd89eb6cf1e07488f
LLR: 2.93 (-2.94,2.94) <-2.25,0.25>
Total: 48248 W: 13018 L: 12896 D: 22334
Ptnml(0-2): 32, 4773, 14400, 4879, 40
closes https://github.com/official-stockfish/Stockfish/pull/4088
bench
5578988
// Decrease/increase reduction for moves with a good/bad history (~30 Elo)
r -= ss->statScore / 15914;
// Decrease/increase reduction for moves with a good/bad history (~30 Elo)
r -= ss->statScore / 15914;
- // In general we want to cap the LMR depth search at newDepth. But if reductions
- // are really negative and movecount is low, we allow this move to be searched
- // deeper than the first move (this may lead to hidden double extensions).
- int deeper = r >= -1 ? 0
- : moveCount <= 4 ? 2
- : PvNode || cutNode ? 1
- : 0;
-
- Depth d = std::clamp(newDepth - r, 1, newDepth + deeper);
+ // In general we want to cap the LMR depth search at newDepth, but when
+ // reduction is negative, we allow this move a limited search extension
+ // beyond the first move depth. This may lead to hidden double extensions.
+ Depth d = std::clamp(newDepth - r, 1, newDepth + 1);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);