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        Arimaa >> General Discussion >> Rules Question
        
(Message started by: jdb on Dec 10^th, 2005, 9:26am)

Title: Rules Question
Post by jdb on Dec 10^th, 2005, 9:26am

If we are using the rules for the 2006 computer championship, what is the result for the following games?

Case 1)
1w Rc3 Dd3
1b re3 eh1
2w re3e rf3x Dd3e Rc3x

Case 2)
1w Rc3 Dd3
1b rf4 eh1
2w Dd3n Rc3x Dd4e rf4s rf3x De4e

Thanks

Title: Re: Rules Question
Post by Fritzlein on Dec 10^th, 2005, 3:20pm

That's a very interesting question, although it isn't likely to come up. Of course it is a draw in a non-tournament game, but when draws aren't allowed I'm not sure what to think. My preference would be that if a player makes a move which results in both players losing their last rabbit, then the player who made the move wins. The order of the steps within the move matters less to my way of thinking than who was making it happen.

They had a very similar problem in Lines of Action. The goal of LOA is to connect all your checkers into a contiguous mass. However, it is possible to connect all your own pieces with a capturing move that incidentally removes the opponent's only unconnected piece. Many LOA players prefer simultaneous connection to be a draw, but the inventor decreed that whoever makes the move should be declared the winner, because he didn't want there to be any draws.

Title: Re: Rules Question
Post by RonWeasley on Dec 10^th, 2005, 3:28pm

It is possible to move one's own rabbit to goal in the same move as pulling the opponent's rabbit to goal. Arimaa awards victory to the player making this move. To be consistent, I would expect the winner in jdb's simultaneous lost rabbits case to be the player making that move.

Title: Re: Rules Question
Post by Ryan_Cable on Dec 10^th, 2005, 10:15pm

I agree with RonWeasley that it should be a tournament win for gold. Case 1 can be made even funnier as:

1w Rc3 Dd3
1b re3 eh1
2w re3e rf3x Dd3e Rc3x De3e Df3x

Gold has no pieces, but in game terms it is a draw, and in tournament terms it is a win for gold.

Title: Re: Rules Question
Post by omar on Dec 11^th, 2005, 10:58am

Good question Jeff. The "Match Rules" state:

Normally a game would continue when one of the players has lost all the rabbits and end in a draw if both players lose all the rabbits. However if draws are not allowed then a player may also win the game by being the first to capture all of the opponents rabbits.

So if after my move is over, all of the opponents rabbits have been captured then I win. Thus, the player making the move which leads to the otherwise drawn position wins. In general I perfer not to have to disect the move to determine the result. The win/lose conditions don't need to be applied at the step level, but rather only at the move level.

Keep in mind that even in tournaments the default is that no rabbits means a draw. A tournament must declare that draws are not allowed if the result should be a win.

Another strange case (not related to draws) is if you move the opponents rabbit into your own goal (maybe to trap a piece that it was supporting), but then move it back out within the same move, you do not lose.

Title: Re: Rules Question
Post by Adanac on Dec 14^th, 2005, 6:38am

Omar, I have one other related question and I'll use my WC game against PMertens as an example. I was down to my final rabbit and, needles to say, I was very mindful not to blunder it away! But suppose that I had lost my final rabbit: I assume that Paul and I would have continued playing our game to its natural conclusion just to see if I could secure the 3rd natural draw in Arimaa history, despite the fact that it would appear to be an inevitable WC game loss for me. And suppose we had played out the game to its natural conclusion and reached this board position after 125 moves:

PMertens: Ea8 Ra7
Adanc: eb8 mb7 da6

Does Silver miraculously win by immobilization even though I certainly would have psychologically given up hope of winning after losing my final rabbit (due to not being aware of this possibility)? Or, if PMertens weren't immobilized but he ran out of time (okay, Paul losing on time is an unlikely scenario!) would I win or is it a draw due to my absence of goal threats?

Alternatively, suppose the pieces were at the other end of the board:

PMertens: Eb2 Rc2
Adanac: ca4 db4 ec4 md4

At this point, PMertens can simply suicide his rabbit and win by drawing rather than risk losing by attempting to win!! ??? If so, it's a highly counter-intuitive incentive system.

This is a radical departure from chess where if the situation had been:

My opponent: Ke3 Pe2
Me: ke5 ne6

In this situation, the best result I can hope for is a draw. Any hope of victory disappeared when I was lost my mating threats and even in the event that my oponent runs out of time on his clock, it's still a draw! Heck, my opponent could say "enough of this", hurl the pieces across the room, walk out of the tournament hall and it's still a draw (I've never seen anything that drastic but I did see someone at an adjacent board leave the room out of frustration and the game was declared a draw due to no mating threats by the other player).

Title: Re: Rules Question
Post by omar on Dec 14^th, 2005, 1:22pm

Interesting questions Greg. First of all it must be made clear before the start of a game if draws are allowed or not.

If draws are allowed and you have lost all your rabbits, you still have a chance to win by immobilizing the opponent or causing your opponent to run out of time. However, if your opponent see that they are at a risk of losing, it would be better for the opponent to suicide the rabbits and make it a draw rather than risking a lose.

If draws are not allowed then the game is over as soon as you lose the last rabbit. The gameserver currently would let you keep playing, but for the WC games I would enter it as a lose for the first player that lost all the rabbits.