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Topic: Arimaa at Boardspace.net (Read 4590 times) |
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rbarreira
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Re: Arimaa at Boardspace.net
« Reply #15 on: Dec 10th, 2010, 3:10am » |
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on Dec 9th, 2010, 11:48pm, Fritzlein wrote:| The full sentence might read, "A player may pass some of the steps, but may not pass the whole turn or make a move equivalent to passing." Does this strike folks as being less open to misinterpretation? |
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I agree that this would make the rules clearer.
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omar
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Re: Arimaa at Boardspace.net
« Reply #16 on: Dec 16th, 2010, 10:11am » |
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Thanks for that suggestion Karl. That does make it more clear and sounds less wordy. I've updated the rules page.
Feel free to suggest other wording changes.
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ddyer
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Re: Arimaa at Boardspace.net
« Reply #17 on: Dec 17th, 2010, 5:26am » |
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on Dec 16th, 2010, 10:11am, omar wrote:Thanks for that suggestion Karl. That does make it more clear and sounds less wordy. I've updated the rules page.
Feel free to suggest other wording changes. |
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I suppose only Omar gets a vote, but I still get an opinion. I don't think this change, or the previous change to forbid "3 repetitions" is a good idea.
The "equivalent to a pass" wording change is not a neutral change that only outlaws meaningless moves. Case in point the "elephant walks in a circle" situation. The elephant "stepped away" in pursuit of some goal the robot saw, but the emergent behavior that dominates the position is that the elephant is guarding the trap. The depth thresholds on the search were perfectly aligned so it saw no harm in stepping away, but once committed to the step-away, the need to step back became visible over the horizon.
Consequently, with the step back forbidden, the camel will be lost.
Similarly, in situations where the robot "naturally" would play infinite repetitions, forbidding the repetition just forces it to do something else that is poorly motivated, resulting in weaker play and tedious near-repetition that goes on forever - or at least until some move randomy pertubs the loop or the game is lost on time. When the robot is strategically bankrupt, forbidding repetition doesn't make it any smarter. A smart robot would offer (and accept) an agreed draw. Allowing it to just play a draw is good alternative.
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rbarreira
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Re: Arimaa at Boardspace.net
« Reply #18 on: Dec 17th, 2010, 6:57am » |
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There was no change, omar just clarified the rules. Moves which don't change the board haven't been legal for a long time (if ever).
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Fritzlein
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Re: Arimaa at Boardspace.net
« Reply #19 on: Dec 17th, 2010, 10:51am » |
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on Dec 17th, 2010, 5:26am, ddyer wrote:| The "equivalent to a pass" wording change is not a neutral change that only outlaws meaningless moves. |
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Nobody claims the rule is meaningless, or that it doesn't make a difference what the rule is. You are right, it isn't neutral. But it isn't a rule change; it is a wording change to make clear what the rule has always been here on arimaa.com.
on Dec 17th, 2010, 5:26am, ddyer wrote:| When the robot is strategically bankrupt, forbidding repetition doesn't make it any smarter. A smart robot would offer (and accept) an agreed draw. Allowing it to just play a draw is good alternative. |
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Yes, the "natural" outcome between two strategically bankrupt bots is often a draw if neither one is programmed to advance against opposing traps. Omar was fully aware, however, that allowing draws by repetition logically mandates allowing agreed draws as well. With an eye to human players rather than bots, he very much wanted to forbid agreed draws. The point is that, unlike chess draws, Arimaa draws are not natural outcomes between players who are strategically aware. Indeed, there has yet to be a single documented human vs. human game of Arimaa which "should" have been drawn with correct play on both sides. There have only been a small handful of instances in which the player with the superior position misunderstood and thought that repeating moves was the best he could do. Therefore Omar's decision to ban agreed draws has been justified by the absence of "natural" draws in actual play.
It is possible (according to Mark Steere, inevitable) that someday some two human players will drag on a game of Arimaa indefinitely, not because they misunderstand the position, but rather because there is legitimately no way for either to win, at which time Omar's repetition rule will look awkward and wrong. Until that happens, however, forbidding draws by repetition is only a problem for dumb bots. Humans that want to repeat position need to learn better.
Of course, Omar's attempt to control the gaming experience can always be thwarted by gamers themselves. Any game community can insist on their inalienable right to agree to draws, their right to repeat position, and for that matter their right to play with no cats, three dogs, and a turkey instead of the standard set of pieces. That's the wonderful thing about the way games evolve; ultimately the game designer is not the only one who gets a vote. A modern example of this is Sid Sackson's game Lines of Action, which he intended to be drawless, but which is played by all serious human players with alternate rules that permit draws.
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| « Last Edit: Dec 17th, 2010, 11:20am by Fritzlein » |
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ddyer
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Re: Arimaa at Boardspace.net
« Reply #20 on: Dec 17th, 2010, 11:33am » |
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It's certainly should be possible to construct positions where it's clear that the game is locked into a draw. I haven't done so, but I'd start a construction around the idea of both players protecting their last rabbit from a trap.
In that case, with one or two extra (weak) pieces each, you'd have a situation where a virtually infinitely long game could occur before the repetition rule would force a resolution.
In any case, the only alternative to an agreed draw in human to human play is time limits, which is not a very satisfactory resolution either. Imagine Omar's chagrin if the programming challenge is eventually won by a program that plays for a draw and then wins on time.
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Janzert
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Re: Arimaa at Boardspace.net
« Reply #21 on: Dec 17th, 2010, 12:59pm » |
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Sorry if my initial reply about the ambiguity of the rule led anyone to believe the actual use by the Arimaa community wasn't completely settled as a "no pass" rule. Here are a few past conversations surrounding this rule that might help show its status:
In the 2008 rule change thread, Omar lists the order of end game checks which start with "3rd time repetition and moves which don't change the board position are rejected". A few posts later a discussion starts around dropping the "no pass" rule.
In November 2006 Fritzlein considers the importance of the rule.
In March 2006 Ryan Cable mentions that swapping two identical pieces still falls under the rule and is illegal.
Janzert
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Fritzlein
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Re: Arimaa at Boardspace.net
« Reply #22 on: Dec 17th, 2010, 1:10pm » |
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on Dec 17th, 2010, 11:33am, ddyer wrote:| It's certainly should be possible to construct positions where it's clear that the game is locked into a draw. |
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Correct. We can construct such positions. The simplest is to put all rabbits of each player on his fourth rank, with his other pieces behind.
Quote:| you'd have a situation where a virtually infinitely long game could occur before the repetition rule would force a resolution. |
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Correct. But such a situation has never arisen in any real game.
Quote:| Imagine Omar's chagrin if the programming challenge is eventually won by a program that plays for a draw and then wins on time. |
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Yes, that's theoretically possible, and it would be very embarrassing. But so far even humans who are better than the best bots have had no luck at all playing for a draw.
As soon as we have one game, just one, the first one in the history of Arimaa, where there is no good alternative to an essentially infinite deadlock, then Omar will have to decide whether he likes his current rule of imposing a time cutoff and awarding the win to the player with more pieces, or to Silver if there have been no exchanges. I will probably think that his "unnatural" imposition of a win for one player is a worse solution than allowing the game to be drawn, but maybe I won't think that, depending on how the deadlock came to pass. In any case, for now it is purely hypothetical what would be the best alternative to allowing a draw, or whether allowing draws would itself be best, because the situation simply hasn't come up.
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| « Last Edit: Dec 17th, 2010, 1:51pm by Fritzlein » |
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Fritzlein
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Re: Arimaa at Boardspace.net
« Reply #23 on: Dec 17th, 2010, 1:37pm » |
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on Dec 17th, 2010, 12:59pm, Janzert wrote:| Here are a few past conversations surrounding this rule that might help show its status: |
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Thanks for the links, Janzert. I note with amusement that by 2008 I had forgotten that JDB had already in 2006 demonstrated mutual-zugzwang endgame positions. Has there ever been a case of zugzwang (even one-sided) in an actual human vs. human game? I can't recall any, but clearly my memory is not reliable. 
Zugzwang is a separate issue from the handling of repetition, but it is similar in that intuitions will vary, and that some players will feel wronged that they are not allowed to pass even when passing would be better than any available move. Chess players probably won't object to the Arimaa rules, since they are used to a lifetime of zugzwang, but I can see the case that it is somehow unnatural to give a win to player who couldn't make progress in the face of passes, but can win when his opponent is forced to move.
On the other hand, the entire theory of games developed by John Conway et al in Winning Ways For Your Mathematical Plays is based on zugzwang, so they would probably be opposed to a campaign to allow passing in all games. 
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| « Last Edit: Dec 17th, 2010, 2:21pm by Fritzlein » |
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omar
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Re: Arimaa at Boardspace.net
« Reply #24 on: Dec 20th, 2010, 10:39am » |
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on Dec 17th, 2010, 1:10pm, Fritzlein wrote:
As soon as we have one game, just one, the first one in the history of Arimaa, where there is no good alternative to an essentially infinite deadlock, then Omar will have to decide whether he likes his current rule of imposing a time cutoff and awarding the win to the player with more pieces, or to Silver if there have been no exchanges.
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Even if that occurs one would have to show that it was a game with perfect play by both sides and there was no other alternative. But even if this started happening on a regular basis with non-perfect, non-cooperative play, it would become a problem. Fortunately we're not there yet.
Interestingly in Havannah also it is possible to construct drawn positions, but they never occur with normal non-cooperative play.
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ddyer
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Re: Arimaa at Boardspace.net
« Reply #25 on: Dec 30th, 2010, 1:21pm » |
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I've installed another significant upgrade at Boardspace. Please throw rocks.
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Fritzlein
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Re: Arimaa at Boardspace.net
« Reply #26 on: Dec 30th, 2010, 8:22pm » |
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on Dec 30th, 2010, 1:21pm, ddyer wrote:I've installed another significant upgrade at Boardspace. Please throw rocks.
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Nice interface, but [rock] the bot averaged over four minutes per move, which is waaaaaay too slow. [/rock] Thanks again for getting Arimaa up on boardspace!
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ddyer
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Re: Arimaa at Boardspace.net
« Reply #27 on: Dec 30th, 2010, 9:11pm » |
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I agree about the speed. I've backed off to a weaker
version that runs a lot faster.
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Hippo
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Re: Arimaa at Boardspace.net
« Reply #28 on: Dec 31st, 2010, 4:43am » |
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on Dec 30th, 2010, 9:11pm, ddyer wrote:I agree about the speed. I've backed off to a weaker
version that runs a lot faster.
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Even now it's really, really slow... I have resigned after capturing camel and cats ... [rock]I miss an option to undo a move[/rock]
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DonEsteban
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Re: Arimaa at Boardspace.net
« Reply #29 on: Dec 31st, 2010, 7:52am » |
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Very nice implementation of the game board, ddyer! I hope this will help recruiting more players for Arimaa (already worked for me).
on Dec 16th, 2010, 10:11am, omar wrote:| Feel free to suggest other wording changes. |
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You may consider those as nitpicking, but you kind of asked for it
"But (like pawns in chess) the rabbits cannot move backward."
Moving the part in parenthesis removes any doubt if pawns in chess can move backward or not.
"A push or pull is considered atomic as if the two pieces are moved simultaneously. Thus it is possible for the pulling (or pushing) piece to step into a trap and be removed from the game while completing the pull (or push). "
Adding the text in bold to the above passage should prevent any unnecessary confusion.
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| « Last Edit: Dec 31st, 2010, 7:55am by DonEsteban » |
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