Author: leonid
Date: 15:37:06 07/07/01
Go up one level in this thread
On July 07, 2001 at 16:27:46, Heiner Marxen wrote: >On July 07, 2001 at 12:47:12, leonid wrote: > >>Hi! >> >>If you would like to solve mate then position then look into this: >> >>[D]q2k2q1/1r1q1r2/nRqQqRn1/NqQbQqN1/QQ1K1QQ1/Q2B2Q1/p2b2p1/8 w - - > >Hi Leonid, Hi! > >According to Chest this is a mate in ten with one solution move: > >PV: Qxd7+ Qcxd7 Qb8+ Qxb8 Qxb8+ Rxb8 Rxb8+ Nxb8 Qxb8+ Qc8 Nxe6+ Bxe6 Qcb6+ Rc7 >Q6xc7+ Ke8 Qxg6+ Qf7 Qce7# > >(K7/600, 350 MB hash, 2.3 hours) > >>This position is curious from the point of view that its branching factor (when >>mate is searched by brute force) diminish with the depth of search. Usually it >>is contrary that you can see. > > depth time EBF ># 2 0.01s 0kN 1.00 1- 0 ># 3 0.04s [ 4.00] 1kN 0.97 87- 0 ># 4 0.37s [ 9.25] 17kN 1.03 1272- 0 ># 5 2.62s [ 7.08] 126kN 1.16 11441- 0 ># 6 16.15s [ 6.16] 800kN 1.35 77134- 0 ># 7 90.26s [ 5.59] 4638kN 1.59 435750- 0 ># 8 524.25s [ 5.81] 28147kN 1.88 2418963- 217 ># 9 2157.76s [ 4.12] 116264kN 2.44 9713815- 1536836 ># 10 8206.47s [ 3.80] 441956kN 3.20 36849208- 28101307 > >Yes, for Chest also the effective branching factor (EBF) is decreasing. So this tendency really depend on position. Mine went like this when search is done by brute force: 4 moves - 1.1 sec 52k (NPS) >> Even second variation of this position, that I >>tried by brute force, have the same tendency. Second position was left as more >>tough one. If you want to see it then change position of two pieces on the >>board. White bishop from D3 goes to H7 and black bishop from D2 to H2. > >I have not yet tried that one. > >> I wonder >>even if the second position don't have some solution for blacks but have no time >>to try it. If you will try for blacks, please say me your result if even your >>result was negative. > >I'm not sure what you are talking about. Same board, but with black to move >and mate? > >>Please say your result. >> >>Thanks, >>Leonid. > >Cheers, >Heiner
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