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Subject: Re: Chess problem solving

Author: Timo Saari

Date: 05:56:36 10/05/01

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On October 04, 2001 at 19:40:20, leonid wrote:

>On October 04, 2001 at 14:01:17, Timo Saari wrote:
>
>>On October 04, 2001 at 10:59:24, leonid wrote:
>>
>>>On October 04, 2001 at 01:52:13, Timo Saari wrote:
>>>
>>>>I am rewriting an old chess problem solver program and as of now it can solve
>>>>normal mate in n moves type problems when n is not too large. It does a brute
>>>>force type search and uses a hash table and killer heuristic. I assume that in
>>>>order to make it reasonably fast with more challenging problems (n>6) I need to
>>>>implement at least move ordering and perhaps special handling of plies near the
>>>>leaves of the search tree.
>>>
>>>Can you explain what was your chess problem program? When it was written and
>>>how? What language you use and what are your plans about your next program as
>>>hardware and system expectation?
>>>
>>
>>The original program was written in late 70s in Algol language for Burroughs
>>B6700 mainframe. It did solve problems but was not very efficient. Some time ago
>
>This is very interesting! I have impression that I know absolutly nothing about
>Algol language or B6700 mainframe. What were those mainframes at that time? 64
>bits machine? And at what speed? Mhz? Do we have some of those computers still
>at work?

The B6700 was an ancestor of the still alive NX/LX-series of computers by
Unisys. It is based on stack architecture with memory of 48 bit words (+ 3 or 4
tag bits) and it never was a number cruncher but more suitable for business like
applications. Algol(in some variations) was/is used as system programming
language; there is no assembler level language.

Timo
>
>Cheers,
>Leonid.
>
>
>
>>I decided to start to learn to program in c/c++ especially for Windows
>>environment and when thinking of a suitable project I remembered the old
>>program. I have written a GUI (a visible chessboard and basic position handling)
>>and adapted the old program to be the search engine. When solving the problem
>>the program produces an expandable search tree (limited depth) that can be used
>>to show the position corresponding various tree nodes.
>>
>>My plan now is to try to make the search faster for more challenging problems.
>>
>>>I think that I can say about mate solver something that I saw before I started
>>>writing it. Doing it was nothing more but putting into work something that look
>>>obvious. Will say you anyway, maybe it will be useful.
>>>
>>>1) Checking moves goes first.
>>>
>>>2) Specilized writing of two plys.
>>>
>>>When you have to find mate just two plys deep:
>>>
>>>a) attacking side produce only checking moves.
>>>b) responding side should find only one legal move to stop search.
>>>
>>
>>Your points do indeed confirm also my initial plans; actually points a) and b)
>>are in the program already and perhaps the first new thing to implement should
>>be 1)(as adviced by Heiner Marxen as well).
>>
>>Thanks,
>>
>>Timo
>>
>>>Expect very soon see your program at work!
>>>
>>>Cheers,
>>>Leonid Liberman.
>>>
>>>
>>>>Can somebody point me to any existing information on abovementiond topics?
>>>>
>>>>Any help appreciated.
>>>>
>>>>Timo



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