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Subject: Re: Is my branching factor normal ?

Author: Tord Romstad

Date: 07:32:32 07/04/04

Go up one level in this thread


On July 04, 2004 at 09:53:04, Jan K. wrote:

>Well, this position is a little bit too hard for my engine :) What time do you
>need to reach depth 9-12,

Gothmog 1.0 beta 10, on a PIV 2.4 GHz:

 1        0.84     0.00        157 Bxa6 bxc3
 2        0.62     0.01       1299 Bxa6 hxg2 Qxg2 bxc3
 3        0.62     0.05       2688 Bxa6 hxg2 Qxg2 bxc3
 4        0.44     0.17      12339 Bxa6 exd5 Nxd5 Nfxd5
 5        0.41     0.75      36429 Bxa6 exd5 Bb7 Qxe5 Bxa8 Nxa8
 6        0.09     1.21     110551 Bxa6 exd5 Nxd5 Nfxd5 Nc4 Nxc4 Bxc4 hxg2
 7       -0.25     2.30     323244 Bxa6 bxc3 Bxc3 exd5 Ng4 hxg2 Qxg2 dxe4
                                   Nxf6+ Bxf6 Bxf6 Qxf6
 8       -0.25     3.79     580979 Bxa6 bxc3 Bxc3 exd5 Ng4 hxg2 Qxg2 dxe4
                                   Nxf6+ Bxf6
 9       -0.31     8.03    1346012 Bxa6 exd5 Nxg6 fxg6 Nb5 Kd8 gxh3 c6 Nd4
                                   dxe4
10       -0.38    17.45    3002608 Bxa6 exd5 Nxg6 fxg6 Nb5 Kd8 O-O-O dxe4
                                   Qb3
11       -0.50    42.34    7643048 Bxa6 exd5 Nxd5 Nfxd5 Nd3 f5 e5
12       -0.34     1:51   20771865 Bxa6 bxc3 Bxc3 exd5 Ng4 hxg2 Qxg2 Rh4
                                   Bxf6

Effective branching factors:
1->2:   8.27
2->3:   2.07
3->4:   4.59
4->5:   2.95
5->6:   3.03
6->7:   2.92
7->8:   1.80
8->9:   2.32
9->10:  2.23
10->11: 2.54
11->12: 2.62

The high numbers for the first few plies are annoying and typical.  I haven't
found a good way to solve this problem.  It seems like most other engines
also suffer from this defect.

>on what hardware and what is the right move here?

There is no "right move".  This is an artificially constructed position
by Peter McKenzie, designed to be used as a "torture test" when implementing
and debugging move generators.  You will see that castling moves, en passant
captures and promotions are possible within the first few moves, which makes
this position very useful to find move generator bugs.

Tord



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