This patch continues work on altering search for ttPv nodes, using recent idea to alter it more in not PvNodes. Previous tweak based on this idea adjusted singularBeta - this one adjusts value of singularLMR, so they are both related to singular extension search.
passed STC
http://tests.stockfishchess.org/tests/view/
5e700737e42a5c3b3ca2e659
LLR: 2.95 (-2.94,2.94) {-0.50,1.50}
Total: 140608 W: 27053 L: 26659 D: 86896
Ptnml(0-2): 2425, 16337, 32439, 16625, 2478
passed LTC
http://tests.stockfishchess.org/tests/view/
5e7068eae42a5c3b3ca2e687
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 79318 W: 10463 L: 10064 D: 58791
Ptnml(0-2): 567, 7416, 23359, 7685, 632
closes https://github.com/official-stockfish/Stockfish/pull/2588
Bench:
4952322
// Decrease reduction if ttMove has been singularly extended (~3 Elo)
if (singularLMR)
- r -= 2;
+ r -= 1 + (ttPv && !PvNode);
if (!captureOrPromotion)
{