Author: Tony Werten
Date: 09:42:19 01/12/02
Go up one level in this thread
On January 11, 2002 at 14:27:47, Dann Corbit wrote: >On January 11, 2002 at 13:00:46, Miguel A. Ballicora wrote: > >>On January 11, 2002 at 12:47:29, David Rasmussen wrote: >> >>>On January 11, 2002 at 12:40:03, Matthias Gemuh wrote: >>> >>>>On January 11, 2002 at 11:44:39, David Rasmussen wrote: >>>> >>>>>[D]2Q2n2/2R4p/1p1qpp1k/8/3P3P/3B2P1/5PK1/r7 w - - 0 1 >>>>> >>>>>In the above position, my search tree explodes because of extensions. It takes > >>>>>3 minutes and 42 million nodes to finish an 8 ply search. How does your program >>>>>do? >>>>> >>>>>Any good ideas on how to limit extensions in such a position. >>>>> >>>>>P.S. Solving the position is no problem. It is a simple mate in 5 plies, and is >>>>>found very early on at depth 1 or 2 or so. Still, there must be something >>>>>unsound about my extensions, or at least room for improvement, when this >>>>>position makes the tree explode. >>>>> >>>>>/David >>>> >>>> >>>> >>>> >>>>My HyLogicChess has the following stats: >>>>All extensions active. >>>>Quiescence moves: 29% (no explosion, my average is normally have 40%) >>>>Total moves searched: 11000 >>>>Speed; 84 kN/s >>>>Move Ordering: 78% (normally 90%..92%) >>>>[1] (0.18) 1.f3 (00h:00m:00s) >>>>[2] (0.12) 1.Qb7 e5 (00h:00m:00s) >>>>[3] (14.50) 1.Qxf8 Kh5 2.Rxh7 Kg4 3.Qxd6 (00h:00m:00s) >>>>[4] (+Mate in 3) 1.Qxf8 Kh5 2.Rxh7 Kg4 3.f3 (00h:00m:00s) >>> >>>My program performs similarly if only searching to ply 4, but try letting it >>>search to ply 9, even though it has already found the mate. That is what I am >>>talking about. >>> >>>/David >> >>Gaviota's output: >> >>setboard 2Q2n2/2R4p/1p1qpp1k/8/3P3P/3B2P1/5PK1/r7 w - - 0 1 >>d >>+-----------------+ >>| . . Q . . n . . | >>| . . R . . . . x | >>| . x . q x x . k | >>| . . . . . . . . | >>| . . . o . . . o | >>| . . . B . . o . | >>| . . . . . o K . | >>| r . . . . . . . | >>+-----------------+ >> >>sd 9 >>go >> 104 1: 0.0 +30.78 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8xd6 >> 392 2: 0.0 +30.78 Qc8xf8 Kh6-h5 Rc7xh7 <EMPTY> >> <-transp >> 455 3 0.0 :-) Qc8xf8 >> 530 3 0.0 :-) Qc8xf8 >> 565 3 0.0 :-) Qc8xf8 >> 1637 3 0.0 :-) Qc8xf8 >> 3104 3: 0.0 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 4023 4 0.1 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 4475 4: 0.1 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 5444 5 0.1 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 8853 5: 0.1 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 11891 6 0.1 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 18148 6: 0.2 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 24692 7 0.2 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 48189 7: 0.4 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 62166 8 0.6 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 152926 8: 1.5 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 172449 9 1.6 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> 262305 9: 2.3 +Mat_3 Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 >> Qf8-g8 >> >>Ply: 9 >>Qc8xf8 Kh6-h5 Rc7xh7 Kh5-g4 Qf8-g8 >>Score: 125.37 (32094) Evals: 90689 Time: 2.3s nps: 115400 Q/all: 0.36 >> nodes cutoffs missed tree_exp >>path 168830 26576 823 1.03 >>quies 93475 31592 1083 1.03 >>all 262305 58168 1906 1.03 >>hashtable= attempts: 284553 hits: 35.3% perfect: 23.2% >>move c8f8 > >For a mate in 3, it does not make any sense to search past ply 5 if you already >see it. After all, when you have searched ply 5 and have a mate in 3, you >cannot possibly improve it. Yes you can. Nullmove and pruning can take care of hiding a short mate until deeper searchdepth. The safe assumption is that when you have a mate in 5 ply and you're deeper than 4 ply in the search you can cut off since it will not improve the score. Tony
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