Author: Robert Hyatt
Date: 10:28:55 02/04/03
Go up one level in this thread
On February 04, 2003 at 13:26:43, Robert Hyatt wrote:
>On February 04, 2003 at 08:37:57, Jarkko Pesonen wrote:
>
>>[D] 4k2r/3p4/p3pQ2/6P1/1pq5/7r/PP6/R1KN1R2 w
>>
>>This is draw , but how do you statically can evaluate that it so?
>>
>>This was the quiescent position and crafty suggested Nc3 bxc3 and not go for
>>repetion(eval 0.09 for crafty statically after these moves but search from this
>>position reveals that this loses rook at lest ) and ruffian correctly wanted to
>>play Kb1 which was the repeating move.
>>
>>
>>Anyway ruffian seems to find drawing lines much sooner than crafty.
>>Does anyone have a glue why it is so fast.
>>It catches draw a few ply earlier than crafty.
>>Is there a way fix this in crafty?
>>
>>
>>Jarkko
>
>
>You are probably mis-interpreting the concept of "draw".
>
>For a program to see a draw by repetition, two things have to happen:
>
>1. It has to believe that one side can _force_ the repetition, if the other
>side plays
>in a particular way.
>
>2. It has to believe that the other side would be worse off it it tries to
>avoid the
>repetition.
>
>All you need in a position like this is to think that one side is is better than
>the other,
>and you might or might not be able to see the repetition. IF one program thinks
>white is slightly better, then it would think that black would try to force the
>repetition
>and white must go along or else get "worse". If another program thinks black is
>better, then it might totally ignore the repetition opportunity.
>
>Usually one side has the option to vary, say in a perpetual check the checking
>side doesn't
>have to check. But he has to believe that if he doesn't check, the opponent has
>a better
>resulting position. If that is not true, the perpetual won't be played.
I tried this position and Crafty spots a repetition instantly:
5 0.04 -Mat04 1. Kd2 Rd3+ 2. Ke1 Qe4+ 3. Kf2 Rh2+
4. Kg1 Qh1#
5 0.07 -0.46 1. Nc3 bxc3 2. g6 cxb2+ 3. Kxb2 d6
5 0.07 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
7 0.15 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
7-> 0.16 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
8 0.33 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
8-> 0.42 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+ (s=2)
9 0.93 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
9-> 1.01 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
10 2.34 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
10-> 2.38 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
11 7.25 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
11-> 7.68 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
12 29.98 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
12-> 30.48 0.00 1. Kb1 Qd3+ 2. Kc1 Qc4+
I'm not sure it could do any better than .07 seconds for spotting this, and this
was not
run on my dual xeon either, but on a quad 550 that is about 1/3 the speed...
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