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Topic: Is never lose possible? (Read 2160 times) |
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haizhi
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Arimaa player #350
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Is never lose possible?
« on: Nov 21st, 2003, 3:39pm » |
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I wonder if playing every move safe in this game , which means instead of taking risk trying to win, just preventing the opponent get anything, can I make a draw every time?
For example, do nothing at every move, except recovering the initial position, can you beat that?
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haizhi
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Arimaa player #350
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Re: Is never lose possible?
« Reply #1 on: Nov 21st, 2003, 3:45pm » |
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Oh, it doesn't mean I am planning to use that, Omar. 
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99of9
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Gnobby's creator (player #314)
 
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Re: Is never lose possible?
« Reply #2 on: Nov 21st, 2003, 7:47pm » |
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Yes you can beat someone recovering initial position each move. However I think you are right that there may exist a purely defensive strategy strong enough to never lose a piece. If played by both sides, it would be a very boring game...
But that would not be a draw... draw is when all rabbits are dead on both sides.
Instead the board would be evaluated when the maximum number of moves is reached (in most cases 100 moves for each player). So the person with the rabbits furthest forward would win...
But in reality, I've never been able to defend that well... naveed always manages to get my camel over his side of the board somehow (or at least a horse).
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fotland
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Arimaa player #211
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Re: Is never lose possible?
« Reply #3 on: Nov 22nd, 2003, 1:38pm » |
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I think you can always pull a rabbit over to your side of the board, and the rabbit moves can't be reversed, so the game must end.
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Janzert
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Arimaa player #247
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Re: Is never lose possible?
« Reply #4 on: Nov 22nd, 2003, 10:29pm » |
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Also don't forget the repeat position rule:
Game Rules-Special Situations
Quote:| If after a turn the same board position is repeated three times, then the player causing the position to occur the 3rd time loses the game. |
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Janzert
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omar
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Re: Is never lose possible?
« Reply #5 on: Nov 28th, 2003, 8:54pm » |
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While the rules were being developed there were some versions in which a defensive strategy could always prevent the opponent from winning. The only and only exception rule in Arimaa is that rabbits cannot move backwards. It was needed so that if someone tries to play only defensively their rabbits could be dragged out and they would be forced to come forward to defend them. Claude likes to use that on me sometimes 
So far no defensive strategy has been found to prevent the opponent from winning. Also if a player only plays defensively the opponent can safely play offensively and win the game.
Of course if both players only play defensively its possible for the game to go on forever. Imagine a bot that only moves it stronger pieces and does not move opponents pieces playing aginst itself.
Omar
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omar
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Re: Is never lose possible?
« Reply #6 on: Nov 28th, 2003, 8:55pm » |
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I ment "one and only".
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99of9
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Gnobby's creator (player #314)
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Re: Is never lose possible?
« Reply #7 on: Nov 29th, 2003, 7:11am » |
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on Nov 28th, 2003, 8:54pm, omar wrote: It was needed so that if someone tries to play only defensively their rabbits could be dragged out and they would be forced to come forward to defend them.
So far no defensive strategy has been found to prevent the opponent from winning. Also if a player only plays defensively the opponent can safely play offensively and win the game.
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But the real question is whether "pulling rabbits out" compromises the aggressor and means he loses other pieces or positional advantage.
If this is the case, then a defensive strategy may still be optimal, though I agree that has not been found yet.
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omar
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Re: Is never lose possible?
« Reply #8 on: Dec 2nd, 2003, 1:54pm » |
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The aggressor only needs to send the elephant forward in order to pull out the rabbits. So I think it tips the game in favor of the aggressor.
Omar
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99of9
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Re: Is never lose possible?
« Reply #9 on: Dec 16th, 2003, 3:11pm » |
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But if the opponent has also sent his elephant forward, the time the aggressor spends trying to pull out a rabbit may allow the perfect defender to pull a cat into a very vulnerable position, and win the game for example.
All I'm saying is that until Arimaa is solved (yeah right!), we shall never know if the perfect game is neverending defence. (except for the repetition rule of course, which forces a finish in many billions of moves).
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omar
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Re: Is never lose possible?
« Reply #10 on: Dec 19th, 2003, 9:51pm » |
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Yes, it's very hard to speculate on what the perfect game would be like. But I wasn't able to find any obvious strategies that can prevent an opponent from winning. Of course they may still exist.
Omar
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Keith
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Arimaa player #4
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Re: Is never lose possible?
« Reply #11 on: Dec 21st, 2003, 1:20am » |
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During playtesting Omar and I deliberatly tried games where one player tried an all out defense. At that time Rabbits could move backwards and the games helped lead to removing the Rabbit's ability to retreat.
We did not play many games this way so I can't say we reached any conclusive results. From what I remember offense was stronger than defense but not by a lot. With careful play the offensive player could pull pieces out of the defensive players setup so that they could not return to their starting positions the next turn. However, it was clear it would take a lot of slow dull work to force a win.
Since then Rabbits have lost the ability to retreat, a scoring mechanism that encourages Rabbit advancement was developed, and turn limits on games all combine to make the holdout game unviable.
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clauchau
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Re: Is never lose possible?
« Reply #12 on: Dec 21st, 2003, 3:24pm » |
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Experiments with one-ply bots and a million games also confirm that attacking strategies are winning over defending strategies.
For example, among strategies directly caring about the official Arimaa score R+P*(C+1),
the bot immediately decreasing its opponent's score as much as possible is weaker than
the bot immediately increasing its score as much as possible, which is weaker than
the bot immediately increasing (its score minus its opponent's score) as much as possible, which is weaker than
the bot immediately increasing (its score minus a hundredth of its opponent's score) as much as possible.
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