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Subject: Re: One test position

Author: Andrew Williams

Date: 09:48:36 06/26/03

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On June 26, 2003 at 11:18:26, Igor Gorelikov wrote:

>One Test position
>==================
>
>There is a section of everyday's puzzles on my site:
>http://www.digichess.gr/infiniteloop/home.php
>
>All puzzles are taken from engine to engine games of Infinite Loop.
>
>Prior to publish a puzzle on my site I always offer Crafty 19.3 to solve it.
>
>I was amazed that today's puzzle was hard to solve even for Crafty so it
>can be a good test position for any chess engine.
>
>What Phalanx XXII (engine number 10 among free WB engines) plays here as
>white (and find it at once)?
>
>[D] r1bq3r/ppp3pp/3k4/3p4/3nP1Q1/8/PP4PP/RN3RK1 w - - 0 17
>
>PS: Yace can find it after some time too.
>
>Best regards,
>Igor Gorelikov

PostModernist (Athlon 1200) likes e5+ after about 2.5 seconds and sticks with it
for a long time. It's currently searching depth 14 after 31 minutes, and the
score is rising above +1 for the first time:

 8>  +0.00   00:00:01.29    124572   1.Qg3 Ke6 2.Qg4 Kd6 3.Qg3 Ke6 4.Qg4 Kd6
                                     5.Qg3 Ke6 6.Qg4 Kd6 7.Qg3 Ke6 8.Qg4 Kd6
 8b  +0.01   00:00:02.51    273552   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4
 8<  +0.36   00:00:03.06    357675   1.e5
 8=  +0.34   00:00:03.07    359990   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 c6 4.Qf4 Kc5
                                     5.b4 Kb6 6.Nc3
 9<  +0.34   00:00:08.25   1139143   1.e5
 9>  +0.25   00:00:08.98   1287446   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Nc3 Rf8
                                     5.Qb4 Kd7 6.Qxb7
 9=  +0.26   00:00:09.17   1342746   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Nc3 Rf8
                                     5.Qb4 Kd7 6.Qxb7
10>  +0.26   00:00:09.98   1454792   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Nc3 Rf8
                                     5.Rfe1 Ke7 6.Rad1
10<  +0.82   00:00:28.91   4055771   1.e5
10=  +0.75   00:00:31.10   4507277   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Nc3 Rf8
                                     5.Ne4 Kc6 6.Rfc1 Kd7 7.Nc5
11<  +0.75   00:01:23.76  11351577   1.e5
11>  +0.61   00:01:47.63  15449058   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Nc3 c6
                                     5.Ne4 Kc7 6.Qe5 Kb6 7.Qxe6 dxe4 8.Qxe4
11=  +0.65   00:01:48.33  15571854   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Nc3 c6
                                     5.Ne4 Kc7 6.Qe5 Kb6 7.Qxe6 dxe4 8.Qxe4
12<  +0.65   00:04:48.80  41307350   1.e5
12>  +0.45   00:07:08.63  64619637   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Re1 Kd7
                                     5.Nc3 c6 6.Qg7 Qe7 7.Qe5 Qf7
12=  +0.50   00:07:09.79  64831671   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Re1 Kd7
                                     5.Nc3 c6 6.Qg7 Qe7 7.Qe5 Qf7
13>  +0.50   00:07:47.04  69753705   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Nc3 c6
                                     5.Ne4 Kc7 6.Nc5 Qd6 7.Qg7 Bd7 8.Nxd7 Qxd7
                                     9.Rf7
13<  +0.85   00:25:22.84 221484627   1.e5
13=  +0.83   00:26:17.63 230022136   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Nc3 c6
                                     5.Rae1 Re8 6.Qg7 Qc7 7.Qe5 Kd7
14>  +0.83   00:29:35.61 254958737   1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Nc3 c6
                                     5.Rae1 Re8 6.Qg7 Qc7 7.Ne4 dxe4 8.Rd1


It's going to take a long time to complete depth 14, so here is PM's "analysis
mode" output after 37 minutes:

time:00:37:48:04
depth=14 score=+125
nodes=319377591 nps=140756
[+125 <= +132 <= +100000]
PV: 1.e5 Kxe5 2.Qxg7 Kd6 3.Qxd4 Be6 4.Nc3 c6 5.Rae1 Re8
    6.Qg7 Qc7 7.Ne4 dxe4 8.Rd1

This means that PM's MTD(f) search has established that the score is > +1.25 and
is now checking to see if it's higher or lower than +1.32

Cheers

Andrew



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