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        Arimaa >> Bot Development >> bot_GnoBot
        
(Message started by: 99of9 on Nov 7^th, 2003, 11:30am)

Title: bot_GnoBot
Post by 99of9 on Nov 7^th, 2003, 11:30am

bot_FirstTry has evolved... he is now called bot_GnoBot when he plays 3 minutes per move.

He's had a few hillarious games with arimaazilla recently - they both appear extremely stupid.

Games with Quantum_Leapfrog are very interesting, because Leapfrog focusses on getting one passed rabbit, and Gnobby is quite defensive, so they have great tussles on the backline.

Title: Re: bot_GnoBot
Post by 99of9 on Nov 8^th, 2003, 8:55am

40k/sec and beating arimaazilla fairly consistently! woohoo.

Omar I'm worried that no human is going to be willing to spend the hours required to finish a 3min/turn game. Let alone 20 games worth! Any suggestions?

Title: Re: bot_GnoBot
Post by 99of9 on Jan 5^th, 2004, 11:17am

The tournament computers can run Gnobot quite quickly compared to my humble home PC. So the tournament version of Gnobot will search to a depth of 4 ply (my move, his move, my 2nd move, his 2nd move). On ply 2, 3, and 4 it only considers 30 possible moves each, chosen based on the evaluations of a 1-ply move generator from that position. On ply 1 however, it simply keeps considering more and more moves until the 3 minutes is up. The number of moves it considers on ply 1 is highly dependent on the board position, and ranges from about 10 at worst, to about 1000.

For some reason the robot sometimes plays after less than 3 minutes... this is a bug, but I haven't yet figured out why it occurs, so for the moment, let's put it down to some kind of higher gnobby intellect...

It also knows about the repetition rule.

Generally Gnobot plays defensively. My aim when constructing the evaluation function was to get it to keep its pieces on it's own side and draw the opponent over (much as naveed does to me in most of our games). However Gnobot is not really sophisticated enough to get the elephant in there and drag a camel back, it will simply wait for its opponent to put a piece within range, and then may try to drag it.

Once a few pieces have been taken, or the opportunity to take over the opponent's trap comes up, Gnobby may move over to the aggressive side of the board. Similarly it may do this if its own camel is taken hostage.

However, that is all a very idealized plan. Gnobby is still not very good because I have not had much time to work on it. So it is likely that Gnobby will lose every game in this tournament. Nevertheless, I still believe that Gnobot's unorthodox methodology has the potential to be very successful in arimaa.