Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Something wrong with my futility pruning?

Author: Bruce Moreland

Date: 17:24:24 12/05/00

Go up one level in this thread



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.

bruce




This page took 0 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.