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Subject: Re: Checkers: Las Vegas and Chinook

Author: martin fierz

Date: 23:13:29 09/11/02

Go up one level in this thread


On September 11, 2002 at 23:08:19, Dave Gomboc wrote:

>On September 11, 2002 at 16:28:37, martin fierz wrote:
>
>>On September 11, 2002 at 07:23:38, Dave Gomboc wrote:
>>
>>>On September 10, 2002 at 17:03:26, martin fierz wrote:
>>>
>>>>if you want to compare, only if you do it properly - so only if i get the
>>>>logfile afterwards :-)
>>>>and i hope you realize that even with the logfile, comparing one position is
>>>>rather meaningless.
>>>
>>>It's not my program, I can't make such a guarantee!  But he is having a party on
>>>Saturday, so if I have a position I can bug him a bit to get him to log in and
>>>run it...
>>>
>>>Yes, I know that comparing one position is meaningless.
>>>
>>>Dave
>>
>>4-8 about 3 moves after 11-15 in the game is the real mistake. 4-8 wins the man
>>but loses. any normal checkers program should want to play 4-8 for a while, and
>>if it's good, it should switch away from 4-8 after some time. the position is
>>rather complicated, so you should make sure that it doesn't switch back. i've
>>changed a couple of things in cake after LV to make it find this faster, which
>>it does, but it still needs a lot of time :-(
>>just try glancing over schaeffer's shoulder to see when it switches to a better
>>move :-)
>>
>>aloha
>>  martin
>
>Okay, I will try. :-)
>
>So are you saying that once you take the checker you're toast?  Like a forced
>loss?  Or are there drawing resources later, but it's just that taking the
>checker is quite a bad move?  And what should it play instead of 4-8?
>Presumably not any move will do?
>
>Dave

yes, there is only one move X to draw in this position AFAIK. and it's not 4-8.
i don't want to bias your answer so i'll just wait and see what you guys get :-)

i have this book generator, i think there are also people in your group who do
this kind of stuff. i let it expand this line after las vegas, and it says 4-8
is a dead loss, and X is a database draw.

in the improved version, cake first wants to go 4-8 with a positive score, then
it starts getting a negative score for it, then it switches to X with a negative
score, and finally the negative score gets smaller. that's the reason i'd like
to see a search log, because from that you can see at what point it realizes
that winning the man is no good, and when it switches to X, and when it realizes
that X is probably a draw. the thing is that at first both moves look good, then
both look bad, and finally 4-8 looks real bad, and X only a bit bad. at least to
cake. so the point where a program has "solved" this position is when it
realizes that X is probably going to draw. not when it displays X as best move,
because for a long while, whether you want to play 4-8 or X is just a matter of
"taste", i.e. some parameters in the eval which have nothing to do with
understanding this position.

aloha
  martin



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