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Subject: Re: What is the branching factor for this position?

Author: Ed Schröder

Date: 23:38:42 08/09/00

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On August 09, 2000 at 11:34:36, leonid wrote:

>On August 08, 2000 at 17:53:36, Ed Schröder wrote:
>
>>On August 08, 2000 at 11:55:12, Philippe Signoret wrote:
>>
>>>This is a position from a game I played against Fritz 5.32 in rated mode 2150
>>>elo
>>>The move rook h4 is winning for black.But it takes a long time for programs to
>>>find it:
>>>30 min for Schredder4, and about 2 hours for Fritz or CM6000
>>>
>>>k1bq2rr/p4p2/PpnBp3/3pP1p1/2pP1nB1/Q1P2N2/1RP2P1P/1R4K1 b - -
>>>
>>>Please try this position with other programs.
>>
>>[d]k1bq2rr/p4p2/PpnBp3/3pP1p1/2pP1nB1/Q1P2N2/1RP2P1P/1R4K1 b - - bm Rh4;
>>
>>Rebel Century 2.0 = 2:33
>>Rebel Century 3.0 (beta) = 1:05
>>
>>Athlon 600 128 Mb
>>
>>Ed
>>
>>
>>00:00  05.08  -0.11  1..Re8 2.Rb5 Nb8 3.Ra5 f6
>>00:01  06.12  0.09  1..Qd7 2.Rb5 Nb8 3.Ra5 f5 4.exf6 Bxa6
>>00:02  07.00  0.09  1..Qd7 2.Rb5 Nb8 3.Ra5 f5 4.exf6 Bxa6
>>00:04  08.00  0.00  1..Qd7 2.Kf1 Nb8 3.Rxb6 axb6 4.Rxb6 Nxa6 5.Rxa6+ Bxa6
>>6.Qxa6+ Qa7 7.Qc6+ Qb7 8.Qa4+ Qa7 9.Qc6+ Qb7 10.Qa4+ Qa7
>>00:07  08.12  0.02  1..Ne2+ 2.Kf1 Nxc3 3.Qxc3 f5 4.Bxf5 exf5 5.Qa3 g4 6.Qa4
>>00:09  09.00  0.26  1..Ne2+ 2.Kf1 Nxc3 3.Qxc3 f5 4.Bxf5 exf5 5.Qa3 Rh3 6.Rd1
>>00:19  10.00  0.41  1..Ne2+ 2.Kh1 Nxc3 3.Qxc3 f5 4.exf6 Qxd6 5.Qe3 Nd8 6.Ra1 Kb8
>>00:37  11.00  0.38  1..Ne2+ 2.Kh1 Nxc3 3.Qxc3 f5 4.exf6 Qxd6+ 5.Qe3 Rh7 6.Ra1
>>Nb4 7.f7 Rgh8
>>01:30  12.00  0.66  1..Ne2+ 2.Kh1 Nxc3 3.Qxc3 f5 4.exf6 Qxd6 5.Qe3 Rg6 6.h3 Bxa6
>>7.Nxg5
>>02:33  12.20  0.66  1..Rh4
>>05:57  12.20  2.69  1..Rh4 2.Nxh4 gxh4 3.Qa4 Rxg4+ 4.Kh1 Na5 5.Rg1 Rxg1+  [h8h4]
>>
>>
>>00:00:03  8.00  0.15   1..Qd7 2.Rb5 Nb8 3.Ra5 Nxa6 4.Rxa6
>>                       Bxa6 5.Qxa6 f5 6.Bxf5 exf5 7.Rxb6  (2) (0.00)
>>
>>00:00:08  9.00  0.10   1..Qd7 2.Kf1 Rd8 3.Bb4 Nxb4 4.Rxb4
>>                       Kb8 5.Ke1 Qc7 6.Rb5 Ng2  (5) (0.00)
>>
>>00:00:18 10.00  0.10   1..Qd7 2.Kf1 Rd8 3.Bb4 Nxb4 4.Rxb4
>>                       Kb8 5.Ke1 Qc7 6.Rb5 Ng2 7.Kf1  (12) (0.00)
>>
>>00:00:38 10.17  0.10   1..Ne2+
>>00:00:39 10.17  0.34   1..Ne2+ 2.Kf1 Nxc3 3.Qxc3 f5 4.exf6
>>                       Qxd6 5.f7 Rg7 6.Ra2 Rxf7  (38) (0.00)
>>
>>00:00:48 11.00  0.46   1..Ne2+ 2.Kf1 Nxc3 3.Qxc3 f5 4.exf6
>>                       Qxd6 5.Re1 Rh7 6.Rbb1 Bxa6 7.Bxe6  (39) (0.00)
>>
>>00:01:05 11.19  0.46   1..Rh4
>>00:01:51 11.19  2.22   1..Rh4 2.Nxh4 gxh4 3.Qa4 Rxg4 4.Kh1
>>                       Bd7 5.Ba3 Rg2 6.Rb5  (65) (0.00)
>>
>>00:02:37 12.00  2.41   1..Rh4 2.Nxh4 gxh4 3.Qa4 Rxg4 4.Kh1
>>                       Bd7 5.h3 Nxh3 6.Rxb6 axb6 7.f3 Nxe5  (120) (0.00)
>>
>>00:10:20 13.00  3.17   1..Rh4 2.h3 Nxh3 3.Bxh3 Rxh3 4.Ne1
>>                       Nxd4 5.Qc5 Ne2 6.Kf1 Bd7 7.Qc7 Qxc7
>>                       8.Bxc7 Nxc3  (371) (0.00)
>>
>>00:16:57 14.00  3.32   1..Rh4 2.h3 Nxh3 3.Bxh3
>>00:40:13 15.00  3.53   1..Rh4 2.Nxh4
>
>
>I am interested to know what is the branching factor for this position.
>Branching factor when you search by brute force.

I ran this position with default settings, no brute force involved.


>Will say, by precaution, what is for me branching factor. If program take 1
>second to search position 5 ply ahead and 5 second for 6 plys, then branching
>factor will be 5.

That is how I see things too.


>When I tried this position and white must move, then my branching factor was 5
>for almost all the plys below ply zero (root ply) and ply beyond it (ply 1). I
>say almost all plys because few plys in my program are done in special way and
>have distict branching factor.
>
>Reason for this question is the big difference that I see between my branching
>factor and branching factor for main programs. The most frequently mine is too
>bad. Hiarcs is nice exception that make me feel good. But why other programs
>have so good branching factor? Maybe they do some search that is "good enough"
>and that they boldly call "brute force search"? Or those programs use some
>techincs that I never could find on my own?

If you do a "brute force" search you usually get a branch factor of 4-6.
Selective search is a way to lower the branch factor.

Ed


>Thanks for responding,
>Leonid.



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