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Subject: Re: Very easy mate to solve.

Author: leonid

Date: 17:51:48 12/30/01

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Hi!

>> Do you really
>>have attacking and defending side going into different move sorting (alignment)?

>Yes.

Now I see that your mate solver have more differenciation that mine have.

>>In my program (never mind what side was initially asked to look for mate) all
>>"move sorting" for two colors (for two move sortings) goes in identical way.
>>Reason for identical search (at least in my mind) is in the fact that defending
>>side also will look for many possible mates during entire search. Each time when
>>"defensive side" will respond with mate, offensive side will stop searching.
>>This will speed entire hunt for mate.
>
>Aha!  I see!  That is what I call the "anti" heuristic, although in Chest it
>is very limited (to immediate mate moves).

What is "immediate mate move"?


>>Here once again I must take care. Will give rustic and simple explanation. Best
>>move in mate solver is the move that lead to mate. Previously found best move is
>>used for putting the most successful at the head of chain. Each best move for
>>its ply. Here also one important moment. If previous best move was "passive
>>move" it will not jump to the head of move chain over "active moves". It will go
>>only at the head of passive moves.
>
>That really sounds like a (special sort of) killer heuristic.

Will try to remember this strange expression.

>>>How exactly are these moves "used"?
>>>What exactly triggers the saving of another move (replacement)?
>>
>>Only when next move that lead to mate for this ply ply was found. Only then
>>previous best move will be replaced.
>
>So a defensive move only is remembered as "best active" move, if it does
>mate the attacking side?  Sounds a bit restrictive.
>While it may help in many of your crowded many-queen positions,
>in more quiet positions (say typical chess problems) this will be extremely
>rare, I think.

Maybe your not symmetrical way could have some sense in my program. I should
verify this when I will be with my solver the next time. Statistics will say how
much it work. Good idea! Thanks!

>>Ha, ha, ha!!!! It look like myself going to some parts of my program that I not
>>touched for years. Very often it is very obscure to me what I wrote there. This
>>is why I leave a lot of description.
>
>... which only helps if that description contains more detail than just
>"it works best this way"  :-)

I don't leave description that something work better that before. In each part
of my program that I wrote (when I really was with it) each part was changed by
hundreds of time. To say that this way is better that other one hundreds will
only bring confusion in description.

>>>My co-author Holger Pause developped the complex part of this move sorting
>>>by try and error, until he was satisfied with the results for a certain
>>>benchmark.  That way some of the things in it are hard to explain, beyond
>>>"it works well that way".

And how Holger wrote its move sorting? Did he started by doing move generator
first? Don't be afraid to be very descriptive. It is just too interesting to
know how other big projects started.

>>All my move sortings was done only after statistical data. Nothing was left to
>>my personal preferences. Even my mistake about "best passive" and "best active"
>>in my mate solver, probably, come from the fact that I tried them in mate solver
>>but came later to something else.
>
>Respect!
>That is the best way to do it:  first measure, then decide.  Scientific.
>Sometimes I do not do a complete measuring (too lazy), and even if I do,
>I often do not document the results of my experiments in a way that can
>be understood years later.  :-(

I still have mate positions created in around 1995 with all time for my program
and other programs that I was able to buy. Recently I looked into my old
positions and found some that took around 5 hours to solve position only 5 moves
deep.

>Well, it is not rocket science, it is just for fun :-)

Probably your program is already rocket science. I do remember buying one chess
program that was written by ex NASA programmer. His chess had very often rupture
in very simple mate positions.

>A happy new year to all of you!

All the best for you and your Chest!!!!

Leonid.

>Heiner



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