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aaaa
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Re: 2008.07.01 Core Rule Changes
« Reply #30 on: Jun 23rd, 2008, 5:51am »
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So to summarize, the immobilization victory condition effectively exists to prevent the turn-sensitive repetition rule from forcing a player to give up the immobilization of an opponent. But I guess it can also be seen as a sort of "mercy rule" as it is hard to see the immobilizer not being able to goal otherwise. Then again, having a loss recorded as immobilization could be considered to be more humiliating.
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Janzert
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Re: 2008.07.01 Core Rule Changes
« Reply #31 on: Jun 23rd, 2008, 8:37am »
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on Jun 20th, 2008, 9:16am, omar wrote:

 
Here is the order of the checking:
 
First check if the move is valid; 3rd time repetition and moves which don't change the board position are rejected here. If the move is OK then add move to the move list and check for win/lose conditions.
 
1. Check if our rabbit reached goal.
2. Check if opponent's rabbit reached goal.
3. Check if opponent has no possible move (immobilization).
4. Check if opponent's only move is 3rd repetition (immobilization).
5. Check if opponent lost all rabbits.
6. Check if we lost all rabbits.

 
If this list could be put in the rules page or somewhere else it would be handy for future bot developers. I know I was looking for something similar when building OpFor.
 
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Fritzlein
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Re: 2008.07.01 Core Rule Changes
« Reply #32 on: Jun 23rd, 2008, 11:21am »
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on Jun 23rd, 2008, 5:51am, aaaa wrote:
So to summarize, the immobilization victory condition effectively exists to prevent the turn-sensitive repetition rule from forcing a player to give up the immobilization of an opponent.

One could argue that a "no pass" rule obviates the need for an immobilization rule.  However, speaking as someone who has twice written up the rules of Arimaa, once for Wikipedia and again for the Arimaa book I hope to publish, I am very sensitive to the comprehensibility of rules.  In the rules, even if I have already said that a player must change the position on every turn, I would also have to say that a player with no legal move loses, or the readers would be confused.  (In chess, for example, passing is not allowed, yet a player with no legal move draws, so the Arimaa rule can hardly be assumed.)
 
Alternatively, supposing that the rules allowed passing, and suppose that the three-fold repetition rule didn't take into account side to move, and suppose the rules specified that a player with no legal move loses.  Although those rules would contain enough information to determine that immobilization is a loss whenever the immobilizer is smart enough to answer a pass with a pass, if the rules contained no explanation, readers would be confused about the rules when encountering immobilization, not to mention any other time a player passes.  An explanation would still be necessary that two consecutive passes force a move if one is available and a loss if one is not.
 
In short, I expect that the immobilization rule does not at all exist for the reason you say; rather it exists to make the rules comprehensible.  Perhaps we could rework four current rules to be restated as three logically equivalent rules, and that might save a programmer a few bits, but such a rewording could make a clear explanation of the rules longer rather than shorter.
« Last Edit: Jun 23rd, 2008, 11:22am by Fritzlein » IP Logged

omar
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Re: 2008.07.01 Core Rule Changes
« Reply #33 on: Jun 23rd, 2008, 9:07pm »
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on Jun 23rd, 2008, 8:37am, Janzert wrote:

 
If this list could be put in the rules page or somewhere else it would be handy for future bot developers. I know I was looking for something similar when building OpFor.
Janzert

 
One could look at he matchOffline code to figure this out Smiley
 
I added this now to the core rules page. Thanks for the suggestion Janzert.
« Last Edit: Jun 23rd, 2008, 9:11pm by omar » IP Logged
aaaa
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Re: 2008.07.01 Core Rule Changes
« Reply #34 on: Jun 24th, 2008, 2:27am »
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Can you please make rabbit elimination have a higher priority than immobilization? It's pretty awkward for bot development otherwise, as one would either have to figure out the possible moves in the evaluation function or have to make partial evaluations at different stages.
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Re: 2008.07.01 Core Rule Changes
« Reply #35 on: Jun 24th, 2008, 6:59am »
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on Jun 24th, 2008, 2:27am, aaaa wrote:
Can you please make rabbit elimination have a higher priority than immobilization?

I rather liked the principle that if a player's move simultaneously meets two victory conditions, then the player making the move wins.  It's some kind of reward for being active, a confirmation that you sometimes have to sacrifice to win.  So I was already uncomfortable with Omar's ruling that if you push an opposing rabbit to goal and simultaneously immobilize the opponent, you lose.
 
on Jun 20th, 2008, 9:16am, omar wrote:
If you immobilize the opponent, but doing so requires you to move their rabbit to goal, you will lose since a rabbit reaching goal is the most primary win/lose condition in Arimaa.

I guess once you are going the route of prioritizing victory conditions, instead of favoring the player who made the move, you might as well rank all the victory conditions as more or less primary.  If we have to rank, I guess "having no legal move" is something to check only after all other victory conditions.  It's a case that must be handled, but it isn't what the game is about.  So I agree with aaaa's ranking.  Intuitively what the game is about is goal, capture, and immobilization, in that order.
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Re: 2008.07.01 Core Rule Changes
« Reply #36 on: Jun 24th, 2008, 8:26am »
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on Jun 24th, 2008, 6:59am, Fritzlein wrote:

Intuitively what the game is about is goal, capture, and immobilization, in that order.

 
I agree with this.
 
On the PASS move proposal, I haven't quite followed the discussion to this point, but I would not like to see PASS be a move alternative.
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Arimabuff
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Re: 2008.07.01 Core Rule Changes
« Reply #37 on: Jun 24th, 2008, 10:52am »
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on Jun 24th, 2008, 6:59am, Fritzlein wrote:

I rather liked the principle that if a player's move simultaneously meets two victory conditions, then the player making the move wins.  It's some kind of reward for being active, a confirmation that you sometimes have to sacrifice to win.  So I was already uncomfortable with Omar's ruling that if you push an opposing rabbit to goal and simultaneously immobilize the opponent, you lose...

I don't know. If you follow the logic of Chess for instance, when you castle you aren't authorized to put your King in check even if it is during a "virtual" position, that is during the castling procedure. That's equivalent to say that you can't put an opponent's rabbit at the goal line even if it is in the middle of a move. If we followed the logic of Chess then the first rabbit to reach the goal-line chronologically (stepwise) or the first last rabbit to be killed would decide who the winner is. Also following that logic, if you kill your last rabbit in order to immobilize your opponent then you'd be the one losing the game since chronologically speaking you’d be the first to be in a losing situation.
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Re: 2008.07.01 Core Rule Changes
« Reply #38 on: Jun 24th, 2008, 10:57am »
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on Jun 24th, 2008, 8:26am, RonWeasley wrote:

 
I agree with this.
 
On the PASS move proposal, I haven't quite followed the discussion to this point, but I would not like to see PASS be a move alternative.

I say "pass move" would be too much of a disturbance to be introduced at this juncture, that is after tens of thousands of games have been played. How many of those games would have taken a radically different direction had the "pass your move" been an option? Nearly all of them most likely.
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omar
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Re: 2008.07.01 Core Rule Changes
« Reply #39 on: Jun 24th, 2008, 11:20am »
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on Jun 24th, 2008, 2:27am, aaaa wrote:
Can you please make rabbit elimination have a higher priority than immobilization? It's pretty awkward for bot development otherwise, as one would either have to figure out the possible moves in the evaluation function or have to make partial evaluations at different stages.

 
I think it does make more sense to have elimination be higher priority than immobilization. Not just for bot developers but also as Karl mentioned in terms of what the game is about. I will make the changes. Thanks for the suggestion aaaa.
 
Also as Arimaabuff mentioned passing is perhaps not worth considering at this point. Also as Karl mentioned it would complicate the explanation of the rules.
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omar
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Re: 2008.07.01 Core Rule Changes
« Reply #40 on: Jun 25th, 2008, 6:43am »
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on Jun 24th, 2008, 2:27am, aaaa wrote:
Can you please make rabbit elimination have a higher priority than immobilization? It's pretty awkward for bot development otherwise, as one would either have to figure out the possible moves in the evaluation function or have to make partial evaluations at different stages.

 
I just made this change. It still needs to be tested though.
« Last Edit: Jun 25th, 2008, 6:43am by omar » IP Logged
aaaa
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Re: 2008.07.01 Core Rule Changes
« Reply #41 on: Jun 25th, 2008, 3:18pm »
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This suggests a new type of bot-bashing record: Fastest simultaneous goal, elimination and immobilization against a particular bot (per color).
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Re: 2008.07.01 Core Rule Changes
« Reply #42 on: Jun 27th, 2008, 2:44am »
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I am thrilled with these rule changes. The new rule concerning repetition of position is fairer than the old one, and the win by elimination healthily unifies normal and tournament rules. Thank you, Omar!
 
The new scoring system is also more practical than the old one, but, on the other hand, I don't like the way it solves ties when both sides have the same number of pieces. Also, given that the objective of a game of arimaa is to take one rabbit to the last row, it is IMHO a bit illogical not to take it into account in the score. All of us know that having the higher number of pieces on the board doesn't assure the victory at all.
 
I have been thinking a little about it, and I'd like to share with all of you the idea it has occurred to me. Would you, Omar, be so kind as to consider it (or to have it a look, at least)? It is as follows:
 
If the game hasn't ended within the time assigned to it, the game will be won by the player who has advanced more squares with one of his rabbits than the other player with any of his ones (captured rabbits doesn't count, of course). If the tie persists, the game will be won by the LAST player who has had this kind of advantage in a previous position.
 
Example: if Gold's most advanced rabbit is in the fifth row (counting from Gold's nearest row), which it has reached on move 70, and Silver's most advanced rabbit is also in the fifth row (counting from Silver's nearest row), which it has reached on move 72, then the scoring system will assign the victory to Gold.
 
Greetings from León, Spain!
 
« Last Edit: Jun 27th, 2008, 2:48am by gatsby » IP Logged
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Re: 2008.07.01 Core Rule Changes
« Reply #43 on: Jun 27th, 2008, 2:04pm »
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on Jun 27th, 2008, 2:44am, gatsby wrote:
If the game hasn't ended within the time assigned to it, the game will be won by the player who has advanced more squares with one of his rabbits than the other player with any of his ones (captured rabbits doesn't count, of course). If the tie persists, the game will be won by the LAST player who has had this kind of advantage in a previous position.

The score function has almost never come into play, but one of the few cases it was called upon was this game, in which it chose the wrong answer.  Your proposal also picks wrong: the side with a rabbit furthest advanced would have lost eventually if the game had continued.
 
As I look back at that game, however, the problem is not that the scoring function was bad, it was that the game was halted.  The reason to even have a time cutoff is for games that aren't progressing.  The only proper situation for imposing a result is if neither player wants to undertake something active.
 
To put it another way, the game shouldn't hit the time cutoff unless at least one player is doing something wrong.  If there were a situation where both players were playing well and nothing was happening, that would be a flaw in the game design, but in that case, no score function could heal the damage.
 
Therefore, assuming that the design of Arimaa is not flawed, and assuming we make the time cutoff long enough that it is only invoked at the fault of the players, I don't really care if the score picks the player with the better position.  It should just be simple and decisive.
 
Both omar's proposal of who has more pieces and gatsby's proposal of who has the most advanced rabbit are simple and decisive.  How to choose?  I guess I would fall back on what I said in a previous post: the game is about goal first, capture second, and mobility third.  So here is my proposal: when a result is imposed, the winner is whoever has a rabbit furthest advanced, with ties broken by whoever has the most pieces, with further ties broken by whoever has his elephant closest to the center.
 
The good news is that the score function has never mattered in any human game so far.  Let's hope it stays that way!
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Re: 2008.07.01 Core Rule Changes
« Reply #44 on: Jun 27th, 2008, 2:15pm »
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on Jun 27th, 2008, 2:04pm, Fritzlein wrote:
As I look back at that game, however, the problem is not that the scoring function was bad, it was that the game was halted.  The reason to even have a time cutoff is for games that aren't progressing.  The only proper situation for imposing a result is if neither player wants to undertake something active.

 
Another reason for time cutoffs is for tournaments that need to get so many rounds or games played within a certain amount of time. While this isn't much of a concern for the internet based games I imagine it will become a much larger one if (once?) live tournaments become popular. This also means that unfortunately the whatever rule is chosen doesn't effect much now but could be much more important in the future.
 
Quote:
Both omar's proposal of who has more pieces and gatsby's proposal of who has the most advanced rabbit are simple and decisive.  How to choose?  I guess I would fall back on what I said in a previous post: the game is about goal first, capture second, and mobility third.  So here is my proposal: when a result is imposed, the winner is whoever has a rabbit furthest advanced, with ties broken by whoever has the most pieces, with further ties broken by whoever has his elephant closest to the center.
 
The good news is that the score function has never mattered in any human game so far.  Let's hope it stays that way!

 
Although I agree the game is about goals then captures and so on, I think when stopping a game at an arbitrary point and deciding a winner it is better to count pieces before looking at most advanced rabbit.  
 
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