My engine is still simple and uses AlphaBeta (fail-hard), PVS, TT, Null Move, Reverse Futility Pruning, Razoring, Mate Distance Pruning, Minor Promotion Pruning, Late Move Reductions and Killer Moves.
I recently added Aspiration Window search which does a 3 step approach. After searching 1 depth normally it starts using a window of -30/+30, then -200/+200 and if this fails -unlim/+unlim.
I did some measurements on 400 positions (random from some test sets) and I'm wondering if the impact of Aspiration Windows should not be better. Obviously there could be many causes for the results - mainly wrong impementatiion and/or bugs or not good enough implementation of the aspiration feature.
This is why I'd like to ask you if you think these results are totally off or if PVS and Aspiration together really do not have much impact.
Btw. this is a short test searching only to ply 6 on 400 positions - could be a reason for the results as well. But my other features clearly show improvements already at ply6.
Code: Select all
Result (summing up all 400 tests): ============================================================ Test nodes nps time SIZE BASE 197.423.838 274.772.806 315.450 SIZE ALL 52.036.476 241.874.059 95.805 SIZE ASPIRATION 54.422.250 245.262.102 99.795 << impact is negative! more nodes search, longer time needed BASE: Only AlphaBeta and TT ALL: All features except Aspiration Window ASPIRATION: Aspiration WIndow active Test examples: ======================================================== Test Nodes nps search time R6R/3Q4/1Q4Q1/4Q3/2Q4Q/Q4Q2/pp1Q4/kBNN1KB1 w - - 0 1 SIZE BASE 2.304.131 194.032 11875 SIZE ALL 1.317 263.400 5 SIZE ASPIRATION 1.315 328.750 4 rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 SIZE BASE 144.535 241.697 598 SIZE ALL 37.432 256.384 146 SIZE ASPIRATION 49.646 378.977 131 r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - SIZE BASE 344.089 292.593 1176 SIZE ALL 142.740 297.375 480 SIZE ASPIRATION 205.521 322.639 637 1r3rk1/1pnnq1bR/p1pp2B1/P2P1p2/1PP1pP2/2B3P1/5PK1/2Q4R w - - SIZE BASE 277.985 515.742 539 SIZE ALL 9.926 709.000 14 SIZE ASPIRATION 9.958 905.273 11 ... total 400