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Subject: Re: Forced mate so solve...(proof number search)

Author: Dennis Breuker

Date: 05:51:38 02/08/01

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On February 07, 2001 at 21:11:50, leonid wrote:

>On February 06, 2001 at 12:12:58, Angrim wrote:
>
>>On February 06, 2001 at 06:28:19, leonid wrote:
>>
>>>On February 06, 2001 at 02:57:32, Angrim wrote:
>>>
>>>>On February 05, 2001 at 07:23:58, leonid wrote:
>>>>
>>>>>Hi!
>>>>>
>>>>>If you like to solve forced mate position full of "depleted uranium"...
>>>>>
>>>>>[D]NKBN4/QRQ3rR/2Qb2r1/N1b1nb2/B2nbbbB/1RNqqqq1/8/2N2k2 b - -
>>>>>
>>>>>Please, indicate your result.
>>>>>
>>>>>Thanks,
>>>>>Leonid.
>>>>Useing proof number search, with no chess knowlege other than which
>>>>moves are legal and the definition of checkmate, on an Athlon 650mhz:
>>>>:proved that move c5xa7 wins, 15 turns
>>>>:PN:402888 evals, 9241 expands, 56 max ply,  1.96 seconds
>>>>
>>>>not the shortest win, but at least its fairly quick.
>>>>
>>>>Angrim
>>>
>>>Hi!
>>>
>>>Can you give more detailed description of your search program? I am curious
>>>since its base is probably identical to my mate solver. Mine use nothing more
>>>but two parameters (not special value for each piece) that are legality of moves
>>>and presence of check. It is everything that program need in order to find mate
>>>or draw.
>>>
>>>Leonid.
>>
>>It uses a fairly generic proof number search, you might try searching
>>for either "proof number search" or "pn-search" on the web, there are several
>>papers on the topic available.  PN-search is a general tree proving algorithm
>>that is domain independant, although it seems to do better for domains
>>such as game tree searches where there is some concept of mobility being good.
>>If you didn't recognise the name of the search method, it is fairly
>>unlikely that you are useing it.
>>Angrim
>
>Since you wrote about "pn-search" and "proof number search", I found already few
>times those expressions used in few places. If you could in few words indicate
>what those terms signify it will be of real help, at least me.

See http://members.ams.chello.nl/dbreuker/thesis/index.html,
and download chapter 3.

Dennis (d.breuker@REMOVETHIS!chello.nl)

>Thanks,
>Leonid.



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