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        Arimaa >> Bot Development >> Rat
        
(Message started by: BlackKnight on Jul 29^th, 2008, 9:59am)

Title: Rat
Post by BlackKnight on Jul 29^th, 2008, 9:59am

Fritzlein suggested I should start a forum topic about my new bot Rat. So here a short introduction.

Rat uses selective search. Current move categories are goals, captures, retreats, kidnappings, attacks, and some trap protections. So there should be many more to come.
The search is guided to some extend by certain patterns in the position. However, so far I have only defined about 20 patterns.
Rat has nearly no leaf evaluation at this moment. I just added recursion and Rat should now be able to see an opponent's goal in one and she can see if she is going to lose a piece.

Title: Re: Rat
Post by Fritzlein on Jul 29^th, 2008, 10:06am

Thanks BlackKnight! What is the branching factor of the tree you are building at the moment? Obviously it depends on the position, but I was curious whether you are examining closer to 1% of the legal moves, or 10%. In other words, how selective is your selective search?

Title: Re: Rat
Post by BlackKnight on Jul 29^th, 2008, 9:45pm

on 07/29/08 at 10:06:06, Fritzlein wrote:

how selective is your selective search?

Maybe I can provide some numbers of moves generated in recent examples using the current move categories. Moves can be anything between 1-step and 4-step. Rat runs as a P2 bot at the moment.
In game 80743 (http://arimaa.com/arimaa/games/jsShowGame.cgi?gid=80743&s=b), move 15b:
Ply 1: 98 moves
Ply 2: 298 moves
before Rat was convinced there is no way to save the horse or get some material in exchange for it.
In game 80707 (http://arimaa.com/arimaa/games/jsShowGame.cgi?gid=80707&s=w), move 18w:
Ply 1: 336 moves
Ply 2: 2051 moves
to go through the whole tree.

I should mention that Rat currently does not know how to protect/attack the opponent's home traps or how to help a frozen piece., i.e., these moves are not in my list of categories yet.

For future games I will collect those data while she is playing.

Title: Re: Rat
Post by Fritzlein on Jul 30^th, 2008, 4:05am

Wow, that is very selective, particularly for the opponent's response. Thanks for the numbers.

Title: Re: Rat
Post by BlackKnight on Jul 30^th, 2008, 10:06am

Yes, I'm sure I will need to extend that. BotV also was too selective, and even worse he couldn't even generate all moves that belonged to a certain category.

Title: Re: Rat
Post by omar on Jul 30^th, 2008, 1:32pm

Hope you will be able to enter it in next CC. Even if it does not do very well, the approach may still be worth pursuing. Eventually it may prevail. After all humans are also doing extremely selective search :-)