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        Arimaa >> General Discussion >> Endgame Study 1, The Lonely Rabbit
        
(Message started by: jdb on Nov 24^th, 2006, 8:53am)

Title: Endgame Study 1, The Lonely Rabbit
Post by jdb on Nov 24^th, 2006, 8:53am

Using the tournament ruleset, who wins the following position and in how many moves?

1w Rd3 Ec1
1b re7
2w pass

The planning window is located at
http://arimaa.com/arimaa/games/planGame.cgi

Title: Re: Endgame Study 1, The Lonely Rabbit
Post by chessandgo on Nov 24^th, 2006, 9:34am

silver I'd say :)

The title seems to indicate you plan to devise more endgame studies ; I'm looking forward to seing them !!!

Title: Re: Endgame Study 1, The Lonely Rabbit
Post by RonWeasley on Nov 24^th, 2006, 9:42am

Silver in 5. Very insightful, jdb.

Title: Re: Endgame Study 1, The Lonely Rabbit
Post by chessandgo on Nov 24^th, 2006, 9:56am

ah, in 5 ? I can only find in 6 ...

Title: Re: Endgame Study 1, The Lonely Rabbit
Post by Fritzlein on Nov 24^th, 2006, 11:11am

I also see the win in six moves for Silver. Gold can prolong it an extra half move by not repeating the position.

1b re7s re6s re5s re4e
2w Ec1n Ec2e Ed2e Ee2e
2b rf4w re4w rd4w rc4w
3w Ef2w Ee2w Ed2w Ec2w
3b rb4e rc4e rd4e re4e
4w Eb2e Ec2e Ed2e Ee2e
4b rf4w re4w rd4w rc4w
5w Ef2w Ee2w Ed2w Ec2w
5b rb4e rc4e rd4e re4e
6w Eb2e Ec2e Ed2e Rd3n
6b rf4e rg4s rg3s rg2s

To my knowledge, this is the first position that proves the repetition rule changes the outcome of the game. There have been plenty of cases in real games in which neither side wants to deviate, but if repetition were a draw by rule, the stronger side could deviate and win anyway. In those positions it doesn't matter a whole lot whether the rule is that repetition draws or repetition loses: either way the stronger side wins.

Here, however, the form of the rule does matter, and it makes a Silver win out of an otherwise drawn position. Note also that if the gold elephant had started on b2 instead of starting on c1, this would be a win for Gold instead of a draw, because it would be Silver who would have to deviate.

Thanks for coming up with this position, JDB. It is of great theoretical interest. If nothing else, it should help clarify people's attitudes towards the repetition rule. In my mind, draws are undesirable, and the repetition rule rather elegantly prevents draws. This is a great example of how some rule is required to break what would otherwise be a deadlock, without having the situation they are stuck with in Chinese chess, where a referee has to determine "whose fault" the repetition is.

I can imagine, however, that other people will think that draws are natural and good, and the repetition rule is contrived and awkward.

Title: Re: Endgame Study 1, The Lonely Rabbit
Post by RonWeasley on Nov 24^th, 2006, 12:22pm

Sigh. Just as you said, I didn't consider gold not repeating on the last move. Too much pumpkin juice.

Title: Re: Endgame Study 1, The Lonely Rabbit
Post by DorianGaray on Nov 24^th, 2006, 1:56pm

Am I the only one to have problems with the plan game?

Title: Re: Endgame Study 1, The Lonely Rabbit
Post by 99of9 on Nov 24^th, 2006, 4:24pm

Nice jdb!

Dorian, it worked for me, just by putting the moves into the move box, and making sure they were formatted consistently (with a carriage return after the last move ... not sure if that matters).