Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: here it is.

Author: leonid

Date: 04:52:22 01/18/01

Go up one level in this thread


On January 18, 2001 at 06:09:08, Heiner Marxen wrote:

>On January 17, 2001 at 22:58:10, leonid wrote:
>
>>On January 17, 2001 at 22:27:36, Heiner Marxen wrote:
>>
>>>On January 17, 2001 at 19:41:34, leonid wrote:
>>>
>>>>On January 17, 2001 at 18:43:43, Paul wrote:
>>>>
>>>>>On January 17, 2001 at 18:18:34, leonid wrote:
>>>>>
>>>>>>On January 17, 2001 at 18:10:38, Paul wrote:
>>>>>>>
>>>>>>>My program says mate in 9 for black ... here's a line:
>>>>>>>
>>>>>>>1... Qxb4 2. Rg8+ Ne8 3. Nxe4 Ncxb3+ 4. cxb3 Nxb3+ 5. axb3 Qxa3+
>>>>>>>6. bxa3 Qcc3+ 7. Nxc3 Qxc3+ 8. Ka2 Rd2+ 9. Bc2 Qexb3x
>>>>>>>
>>>>>>>Paul
>>>>>>
>>>>>>Can you indicate by what program you solved and all basic data about solution?
>>>>>>Selective or brute force search, hash table, special mate solver or usual chess
>>>>>>game. Speed of your computer.
>>>>>>
>>>>>>Thanks,
>>>>>>Leonid.
>>>>>
>>>>>Hi Leonid ...
>>>>>
>>>>>It's my own program 'Pretz', selective nullmove search, 48MB hash, usual
>>>>>chess program, 400MHz PII. So it's possible there's a shorter mate.
>>>>>
>>>>>Don't know the exact solving time, cause I had more things running
>>>>>at the same time, but it was a couple of minutes.
>>>>>
>>>>>Paul
>>>>
>>>>Thanks!
>>>>
>>>>Pretty new for me to see that nullmove could be used as some kind of selective
>>>>search for mate.
>>>>
>>>>It is possible that 9 moves is the shortest move. I only found that mate is
>>>>between 11 moves and 7. Six moves I looked through brute force. In six mate not
>>>>existe.
>>>>
>>>>Brute force, even 6 moves took on mine around 6 minutes. Branching factor looked
>>>>very bad for this position. With similar branching factor and having no hash in
>>>>the program, I thought that looking for exact solution will be too long.
>>>
>>>Chest says there is no mate in 7.  214 seconds K7/600 with 20 MB hash table.
>>>Since I have already running a long job, it will take some time to
>>>complete depth=8.
>>>
>>>Heiner
>>
>>Pretty good!
>>
>>Heiner, and how much you think that you can save the time on your mate solver
>>with hash while looking 7 moves deep? I speek about brute force.
>>
>>Recently I was puzzled and disappointed when I found, in one initial trial of
>>hash table (still few questions to solve there), that hash can speed my program
>>(not mate solver) only inside of few initial plys. More deeply plys have too
>>efficent branching factor to be happy with hash. I probably miss there something
>>very simple.
>>
>>Leonid.
>
>I do not have the numbers for depth=7, just for depth=6 (5.4 seconds):
>
>acm statistics:
>   30394/   53825 searched
>    5601/    8763 found (18.4/16.3),    14371 compared [1.000/found]
>   24793/       0 in/out    24793 alive,  499494 free
>apx costs: done 1433844, saved 910258 (0.635), ovhd 84219, speed 1.61
>cost done per sec =  264059.7
>info  made- used- upgr- forg-   made+ used+ forg+
>   1  24785     0 24785     0       8     1     0
>   2  24747  9687  3512     0      22     0     0
>   3   3512   999   598     0       0     0     0
>   4    598    89    80     0       0     0     0
>   5     80     0     1     0       0     0     0
>   6      1     0     0     0       0     0     0
>  63     16     0     0     0       0     0     0
>info       cnt-      cost-       avg-       cnt+      cost+       avg+
>   1      24785 7.5581e+04 3.0495e+00          8 4.0000e+01 5.0000e+00
>   2      24747 1.0987e+06 4.4399e+01         22 3.7800e+02 1.7182e+01
>   3       3512 1.3740e+06 3.9124e+02          0 0.0000e+00 0.0000e+00
>   4        598 1.4188e+06 2.3726e+03          0 0.0000e+00 0.0000e+00
>   5         80 1.4309e+06 1.7887e+04          0 0.0000e+00 0.0000e+00
>   6          1 1.4338e+06 1.4338e+06          0 0.0000e+00 0.0000e+00
>  63         16 6.4000e+01 4.0000e+00          0 0.0000e+00 0.0000e+00
>end of acm statistics.
>
>In this case savings are not dramatic.  Factor 1.61 (or more).
>Recall rate around 17% (hit rate).
>
>In my experience, the TT (transposition table == hash table) saves a bad
>move ordering, i.e. a good move ordering lets the TT look bad.
>
>Also, I do not probe/enter TT entries below some depth.
>Probing does cost, and the probably saved work better be more expensive
>than the probe itself.
>I enter "mate in 2" jobs along with their results, but not "mate in 1",
>since these are just too fast, anyhow.
>
>Also, during mate search I think it is best to only store the boards,
>where white (the attacker) is to move, and not to store the others.
>For a playing program I would store all (if expensive enough).
>
>You see, there are plenty of things to consider, and many chances
>to make mistakes.  ;-)  Heads up!
>
>Heiner

Thanks!

Just one expression surprised me. I had the impression that you said "store the
boards". Do you save in hash table entire chess board position, or just three
moves that lead to it?

In my trying of hash, program was saving three moves that lead to certain
position, to be later compared, and two additional variables. One variable is
value obtained for saved position and one is maximum value that limited search
in lower ply. This lower ply is the ply just under three plys which moves are
saved in hash. Even when during the first trial I dropped this "maximum" value,
that limit well coincidence rate, still my hash was effective only for few first
"three plys pairs".

Expect to put my hash in mate solver after finding what is wrong for chess
program. Anyway, I expect to rewrite everything for Linux. There will be no more
hassle with segments, like with my hash now.

Leonid.



This page took 0.08 seconds to execute

Last modified: Thu, 07 Jul 11 08:48:38 -0700

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