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        Arimaa >> Bot Development >> Two new bots
        
(Message started by: BlackKnight on Apr 28^th, 2005, 1:43pm)

Title: Two new bots
Post by BlackKnight on Apr 28^th, 2005, 1:43pm

Dear all,

I had to take a strict time out, Aamir and Omar, your game is just too addictive ... :)

Anyways, of course I did not forget Arimaa, and so I proposed a Final Year Project for UG students to implement a bot, and they are about to start.
I will be their "technical advisor". For sure their bots will be playing better than mine ... ;)

Any kind of suggestions and hints, possible pitfalls, whatsoever is very welcomed.

The more ideas we get now in the planning phase, the more we can try to integrate from the beginning on.

Thanks for all your suggestions in advance!

(P.S.: Off topic: Two Arimaa players got married: ytri and I, we didn't meet here, but while playing other board games .... ;) )

Title: Re: Two new bots
Post by 99of9 on Apr 29^th, 2005, 8:15am

Wow, congratulations!!!

About the suggestions - I suggest that they learn to play the game a bit before even starting out.

Title: Re: Two new bots
Post by PMertens on Apr 29^th, 2005, 11:47pm

gratulations :-)

Title: Re: Two new bots
Post by 99of9 on Apr 30^th, 2005, 6:43am

Arimanator, I noticed you were surprised by the obviousness of my suggestion. But the reason I say that is because we've seen a previous example of a pair of experienced bot-writers, who came and wrote an arimaa bot together without really learning much about the game. Although it searched incredibly deeply etc, I think they were always handicapped by the fact that the bot threw all its pieces forward all the time.

Title: Re: Two new bots
Post by Fritzlein on Apr 30^th, 2005, 5:27pm

on 04/28/05 at 13:43:18, BlackKnight wrote:

(P.S.: Off topic: Two Arimaa players got married: ytri and I, we didn't meet here, but while playing other board games .... ;) )

Congratulations! It is a blessing to be married to a fellow gamer, as I know from personal experience. Pardon me for being nosy, but did you meet through online games? If so, that is majorly cool.

As for steering future bot writers here, I'm thrilled. It livened things up around here last year to have some new bots put the pressure on Bomb. I think Fotland might have rested on his laurels rather than putting in more development time if there hadn't been some competition. Since the $10,000 seems out of reach for the moment, we need more people fighting for the $500 computer prize to keep each other honest.

It looks like the human vs. human side of Arimaa is finally going to take off, which means that new bots (and the challenge match) won't be as critical to the survival of Arimaa as a sport as they once were, but even so I would be glad if the human vs. machine contest stays interesting.

Title: Re: Two new bots
Post by Fritzlein on Apr 30^th, 2005, 5:42pm

on 04/28/05 at 13:43:18, BlackKnight wrote:

The more ideas we get now in the planning phase, the more we can try to integrate from the beginning on.

Thanks for all your suggestions in advance!

Oh, I had an idea from discussion about piece values that I would like to see someone implement if it isn't too much trouble. I understand that Bomb already has numerical values for trap control, frames, hostages, etc. which are added to the value of the pieces. But the value of the pieces stays constant, so Bomb sometimes seriously overvalues camels and horses relative to the small pieces.

My idea from the piece value thread is that one should estimate how much it will cost the elephant to leave the trap it is currently guarding. Sometimes it costs almost nothing, sometimes it costs a piece, and sometimes it would cost the game. Now, when the elephant is "highly stuck", then the value of the opposing camel goes up, and when the elephant is "highly mobile" the value of the opposing camel goes down.

I don't know how to encode this, and whether or not it would cause weird computer behavior which would be easily exploitable by humans, but if it works for the elephant vs. camel evaluation, it could then be generalized further down the supply chain to give a bot some sense of whether attacking an opposing trap would be profitable or more dangerous than it is worth.

Just my $0.02.

Title: Re: Two new bots
Post by BlackKnight on May 1^st, 2005, 2:33am

Thanks for all your congratulations first of all!

on 04/30/05 at 17:27:51, Fritzlein wrote:

Pardon me for being nosy, but did you meet through online games? If so, that is majorly cool.

I'm very happy to share with you:
During our weekly "Settlers of CATAN" meeting in my flat a friend of mine brought her to join the gathering and introduced her to me...

Title: Re: Two new bots
Post by BlackKnight on May 1^st, 2005, 3:58am

Thanks for your hints again.

I agree with you Toby. The students should also have some experience in playing the game.
I think I remember Jonathan Schaeffer said in his book "One jump ahead" that he is a novice player in Checkers, but he also needed to consult top players to improve Chinook.
Furthermore, he says the evaluation function should be as simple as possible, and it is more important to achieve a deeper search.
However, it seems to me that at this moment the search depth is too shallow so that we need to come up with more complicated evaluations to compensate for that.
I'm a chess player and maybe so I'm biased when I classify chess into a higher level than Checkers and Morris.
And I believe the evaluation function of Chess are also much more complicated. As Arimaa and Chess might have about the same level (in my personal ranking), we also need much more sophisticated evaluation functions here.

In a very first meeting with my students I already mentioned a very basic change of value of the pieces during the game, e.g. if C-C and one pair of H-H has been exchanged, the next horse pair promotes in some sense to the rank of the camels before. Still one could also say that there are only less pieces that are weaker than them, and furthermore one could also say that actually dogs and cats (and rabbits) increase in value.

Fritz, your thinking about value changes is much more advanced than this basic understanding.
As you might discover sometimes when playing against my bot, it tries to run forward with a rabbit, if it "thinks" it could sneak through. This was based on an attempt to change the value of such a rabbit dynamically, and sometimes leads to very weird moves, as I never really had the time to finish it and treat all cases.

So I think it's a great idea of you to try to combine all those aspects you mentioned to adjust the value dynamically.
I hope it would be possible to cast as many things as possible into a "big formula". That would also help to keep the evaluation simpler indeed.
Additionally "running rabbits" could be covered by this as well I believe. Their value close to an opponents trap/side should be quite low if cat and dog are still hunting out there, and especially if a rabbit is running alone.

Title: Re: Two new bots
Post by BlackKnight on May 1^st, 2005, 5:57am

Thanks, and thanks! :)

Yes, my own bot has a lot of things that would need to be changed. It doesn't care about rabbits too much and even not about cat/dog sometimes in an otherwise balanced position. As soon as a rabbit has been dragged over it gives up hope that it could still be saved.
Framing seems to be another thing that it never "understood". ;)

So the students will not start with my unfinished attempt of writing a bot. They will start from scratch.

Title: Re: Two new bots
Post by 99of9 on May 1^st, 2005, 8:42am

on 04/30/05 at 10:48:37, Arimanator wrote:

I just didn't like that you seemed to treat me like a second class citizen by calling yourself a great name but it was probably because I said that I could have taken your camel which was wrong as you correctly pointed out.

I apologise if you felt like a second class citizen by my comment on game 14214, I certainly didn't mean to imply that. You often seem to treat my comments as personal jibes when I had no intentions of this kind. Perhaps this is a long term communication problem on my part.

In my terminology "big names" is very different from "great names". Big names come and go, great names endure. I did not, and would not call myself a great name in anything. Furthermore, I do not think of non-big-names as second class in any sense. In chess I am not a big name, therefore do I think of myself as second class??? No.

I consider that currently I happen to be good/big at arimaa (this may change), but hold no delusions of being great. I consider some (plural) players better than me. This is simply an evaluation of current skill, not a judgement of character or citizenship.

I use these evaluations to improve my win rate in arimaa. I am not a robot, and psychology is part of my game. (I don't want to spell this out any further for fear of giving away my strategy :-))

Would you have been as offended if I'd said "even world champions (which I am not and have never been) can be felled with a single well-aimed rabbit"? I would happily change my comment to that if you prefer it - because it is still just as true. I just thought it would be better to include myself in the fallible group, since I am certainly fallible in the face of well-aimed rabbits.

Did I say it because you said something about being able to win a camel? No, absolutely not, that was a totally unrelated technical point. I do not make revenge comments, and I hope I never will. Sometimes I argue a point if I disagree, but I certainly try to stay on the same topic! In some cases even if I disagree I will try to keep my mouth shut for the sake of not inflaming things. Perhaps I should have kept my mouth shut here too!

on 04/30/05 at 10:48:37, Arimanator wrote:

I am a little prouder of our second game , I just need to control my emotions, but what's life without emotions :).

I agree, the second game was much stronger. And I'm sure in the third you will be stronger still!!

Title: Re: Two new bots
Post by 99of9 on May 2^nd, 2005, 3:06am

on 05/01/05 at 15:17:44, Arimanator wrote:

(sorry don't have the face for blowing up :) ) .

How's this?
http://images.google.com.au/images?q=tbn:IO0f0M6UN3AJ:immanuelumc.org/images/youth_explode_head.gif

:-) Don't worry, I know you're not malevolent (except against bots on the arimaa board)!

If this is a language you can barely speak, I'd recommend that when Fritz takes up his professional psychology, you should take up professional translation or linguistics.

Title: Re: Two new bots
Post by omar on May 4^th, 2005, 10:32am

Hi Gerhard,

Nice to hear from you again. Congratulations to both you an Ye on getting married. Hope you realize you are married to the strongest female Arimaa player; look out :-)

To help out your students with the final year project you might want to create a web page for them with links to Arimaa resources. I would definitely suggest putting a link to the Arimaa page on Wikipedia (very well written and organized thanks to Karl). It will give them a fast start on what we know so far about Arimaa tactics and strategy.

There is also a page on how to get started with developing an Arimaa bot:
http://arimaa.com/arimaa/challenge/devBot.html

You might also want to add links to several resources mentioned on the Arimaa downloads page.
http://arimaa.com/arimaa/download/
For example there is a sample move generator, a sample Arimaa bot, and the database of all the Arimaa games played so far. I will also be adding a program soon to allow offline bot vs bot matches.

When the students want to interface their bot to the Arimaa gameroom they can contact me to get the bot interface kit. I give this out individually because I like to keep track of all the participants who are developing Arimaa bots:
http://arimaa.com/arimaa/challenge/participants.html

If there is anything else which I could provide that you might find useful for the students, please let me know.

Title: Re: Two new bots
Post by RonWeasley on May 5^th, 2005, 11:48am

Quote:

Hope you realize you are married to the strongest female Arimaa player;

That would make her an "Arimaatrix."

Congratulations and we look forward to the bots!

Title: Re: Two new bots
Post by BlackKnight on Jun 24^th, 2005, 6:20pm

on 05/04/05 at 10:32:59, omar wrote:

Hope you realize you are married to the strongest female Arimaa player; look out :-)

Yes, I'm really afraid of playing Arimaa against her! ;)

And once more thanks to everybody for your congratulations!

Toby, thanks for starting the topic "Haizhi's Arimaa Project". I guess we can draw a lot of useful information from this and the comments to the recent games of his bot.

Title: Re: Two new bots
Post by 99of9 on Jun 24^th, 2005, 6:56pm

Sure. I'm happy to comment on the games of your students' bots too. As for most players, I'm better at spotting weaknesses in a bot's game than I am at fixing the bot up.