Author: Severi Salminen
Date: 02:09:47 12/06/00
Go up one level in this thread
On December 05, 2000 at 20:24:24, Bruce Moreland wrote: > >On December 05, 2000 at 16:46:17, Severi Salminen wrote: > >>Hi! >> >>Check out this position: >> >>[D]rnbqkbnr/ppp2ppp/8/3pp3/3PP3/8/PPP2PPP/RNBQKBNR w >> >>With futility pruning my program does this: >> >> >> Time Depth Score Nodes PV >> 0 1 -0.14 175 Be3 >> 0.00 2 -0.19 1851 Be3 Be6 >> 0.11 3 -0.11 7755 Nf3 Bb4+ Bd2 dxe4 Bxb4 exf3 dxe5 Qxd1+ Kxd1 >>fxg2 Bxg2 >> 0.33 4 -0.14 22227 Nf3 exd4 Qxd4 Be6 >> 0.98 5 0.00 67477 dxe5 dxe4 Qd7+ Qxd7 >> 3.07 6 -0.12 324618 Nf3 Bg4 Be2 Bxf3 Bxf3 Bb4+ >> 12.41 7 0.00 1515184 Qh5 dxe4 Qxe5+ Qe7 Qxc7 Qxc7 >> 33.06 8 -0.09 4203195 dxe5 dxe4 Qxd8+ Kxd8 Bc4 Nc6 Bf4 Bb4+ >> >>And without: >> >> Time Depth Score Nodes PV >> 50 1 -0.14 175 Be3 >> 0.05 2 -0.19 1851 Be3 Be6 >> 0.16 3 -0.11 7850 Nf3 Bb4+ Bd2 dxe4 Bxb4 exf3 dxe5 Qxd1+ Kxd1 >>fxg2 Bxg2 >> 0.44 4 -0.14 22555 Nf3 exd4 Qxd4 Be6 >> 1.10 5 -0.09 73064 Nf3 dxe4 Nxe5 Bb4+ c3 >> 2.85 6 -0.12 306521 Nf3 Bg4 Be2 Bxf3 Bxf3 Bb4+ >> 9.61 7 -0.07 1212161 dxe5 dxe4 Qxd8+ Kxd8 Bc4 Bb4+ Nd2 >> 29.33 8 -0.09 3947537 dxe5 dxe4 Qxd8+ Kxd8 Bc4 Nc6 Bf4 Bb4+ >> >>Why the h?%l is the one without futility pruning faster and has less nodes? I >>use futility margin of 2 pawns. >>My futility code is something like: (I prune check now also...) >> >>if(depth==1) >> if(futility_condition(Moves[k].value)<=alpha) >> continue; >> >>the futility_condition() returns the current material balance + the material >>gain of the move+ 200. >> >>Any ideas? >> >>BTW. Does my node counts look reasonable? I'm using MVV/LVA ordering in qsearch >>+ nullmoves (R=2). >> >>Severi > >It switched moves in a later ply in the one where you prune, and this costs >nodes. > >It is not possible to determine whether a pruning technique is good or bad based >upon one position. > >Who may as well decide a coin is lucky or unlucky depending upon whether it >comes up heads the first time. Yes, of course. That's why I asked. In heinz's book he says that tree sizes are shrinked about 60% on average, but in my case this did not happen. It would be nice to have a set of positions with which one could verify these things. Do you now any futility -positions (in which the futility pruning really matters) and affects? Severi
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