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   Author  Topic: Replace the Scoring Function  (Read 5744 times)
browni3141
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Re: Replace the Scoring Function
« Reply #45 on: Apr 30th, 2013, 2:40am »
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on Apr 29th, 2013, 10:44pm, mattj256 wrote:

Thanks for understanding.  You're a good teacher.
 
I'm really not rude enough or patient enough to try this tactic in a live game against a human.  But it would be fun (if I ever had time) to write a really passive-aggressive bot.  Given that bots are so good at tactics, I wonder what would happen if you intentionally program the bot to keep all the pieces safe at home?  I don't mean an elephant-only attack but a really robust strategy of "nothing goes past the fourth rank."  If nothing else, a bot that was able to stall for 30-60 minutes might gain an advantage over a human because the person would get mentally tired but the bot wouldn't be affected.

A bot might be able to pull that off against other bots and maybe weaker humans, but against any decent human it should flop. I'm assuming the bot is allowed to move past the fourth rank when it needs to to avoid losing material. Being purely defensive is a really poor strategy because you are ignoring many good options while the opponent's options aren't limited. It only takes a few inaccurate moves before you're at a tangible disadvantage, and pure passivity is probably not even close to optimal. If any of the top bots implemented a strategy of pure passivity then they would probably be several hundred points weaker. Bots are probably only slightly better than top humans on average when it comes to tactics anyway.
 
Regarding the stamina issue, 30-60 minutes of playing shouldn't wear out the average person. The average player probably wouldn't start to notice much fatigue for at least  4-5 hours. Personally I think that I could last many, many hours and maintain a strong level of play, because I can play well with little mental effort and I can play well when fatigued. If anybody wants to provide an incentive I will gladly prove it Smiley
A 24+ hour marathon might be fun, but it would be hard to schedule it Wink
« Last Edit: Apr 30th, 2013, 2:42am by browni3141 » IP Logged

browni3141
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Re: Replace the Scoring Function
« Reply #46 on: Apr 30th, 2013, 3:49am »
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on Apr 26th, 2013, 12:58pm, Hippo wrote:

 
Actually this was my argument Smiley ... yes even with silver 8 rabbits on row 3 with 8 gold rabbits on rank 2, one piece captured and remaining pieces on row 1 the player finishing the blockade loses. More interesting position would be with 2 pieces sacrified, but with silver elephant on rank 1 ...


it seems silver is winning in first one but losing in second ... when the last step was silver rabbit to a3 in both cases.

The first silver wins regardless of who is to move.
Silver to move:
1s ma8s
2g Cb1w
2s ma7n
3g Ca1e
3s ma8s
4g Cb1w
4s ma7n
5g Cc1w
5s ed1w Rd2s rd3s
Gold to move:
1g Cb1w
1s Cc1w ed1w ec1e
2g Cb1e
2s Cc1w ed1w ec1e
3g Cb1e Ca1e (now it is the original position with silver to move)
3s ma8s
4g Cb1w
4s ma7n
5g Ca1e
5s ma8s
6g Cb1w
6s ma7n
7g Cc1w
7s ed1w Rd2s rd3s
 
The second position gold to move wins by shuffling b1-a1-b1 until silver runs out of moves.
Silver to move also wins the second position, using the same method as in position 1 with gold to move.
I'll post my thoughts on what's been said about the scoring function later. I have not given up, I've just been busy with coursework Smiley
@odin: I find your argument a little unsporting, you act as if you've dealt a death blow Tongue I will post my reasoning later as to why I don't think the point regarding Arimaa being a perfect information game carries much weight.
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Fritzlein
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Re: Replace the Scoring Function
« Reply #47 on: Apr 30th, 2013, 9:07am »
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on Apr 29th, 2013, 10:44pm, mattj256 wrote:
I don't mean an elephant-only attack but a really robust strategy of "nothing goes past the fourth rank."

Back in 2004, when we all attacked with only the elephant, there was a sneaking suspicion among top players that a purely defensive strategy might be possible.  The tacit assumption was that if the opponent advanced anything other than his elephant, it would be to his disadvantage.  You would switch gears, take his second advanced piece hostage, and have an advantage yourself.
 
Of course pure defense involves keeping all rabbits back, because rabbit pulls can't be reversed.  It requires keeping a solid second layer of pieces in front of the rabbits so they are not exposed.  It involves keeping your own elephant on the fourth rank to unfreeze and retreat any non-rabbit pieces the opposing elephant pulls out to the third rank.  However, with all that said, it apparently doesn't quite work to prevent all hostages even if the opponent isn't allowed to advance anything except his elephant.
 
The community was sporadically exploring the finer points of this debate when elephant-horse attacks started popping up on the wing away from the defensive camel, which made the conversation moot.  If your strategy must insure (A) the opposing lone elephant can't ever pull a hostage back to his side and (B) the opposing horses must be kept out of both the b3 and g3 squares and (C) an opposing horse can't ever pull a hostage back to his side, then far from being a "really robust" strategy, pure defense is downright impossible.
 
And from there it got worse for defense-only strategy.  We now know that there are some situations in which even camel advances can't be punished by taking the camel hostage.  If your opponent is allowed to advance elephant, horses, and camel, it is completely hopeless to think "no piece of mine goes past the fourth rank".  There are too many ways for your pieces to get pulled out, too many holes to plug.  If you don't generate some threats of your own, you are dead duck.
 
Unlike in 2004, there is no longer sneaking suspicion among top players.  The debate is completely over.  Like browni says, your opponent has too many ways to hurt you for pure defense to be viable in Arimaa.
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Hippo
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Re: Replace the Scoring Function
« Reply #48 on: Apr 30th, 2013, 12:14pm »
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on Apr 30th, 2013, 3:49am, browni3141 wrote:

The first silver wins regardless of who is to move.
Silver to move:
1s ma8s
2g Cb1w
2s ma7n
3g Ca1e
3s ma8si
4g Cb1w
4s ma7n
5g Cc1wa
5s ed1w Rd2s rd3s
Gold to move:
1g Cb1w
1s Cc1w ed1w ec1e
2g Cb1e
2s Cc1w ed1w ec1e
3g Cb1e Ca1e (now it is the original position with silver to move)
3s ma8s
4g Cb1w
4s ma7n
5g Ca1e
5s ma8s
6g Cb1w
6s ma7n
7g Cc1w
7s ed1w

Oh interesting ... silver passed moving his pieces moving just gold to make his move legal.
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Brendan_M
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Re: Replace the Scoring Function
« Reply #49 on: Apr 30th, 2013, 5:09pm »
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There is another option - the result of a game that ends on time is a loss for both players
 
This satisfies the following criteria:
  • The game will end in a known amount of time
  • The result of the game must be consistently reproducible.  
  • The result of the game must be completely in control of the players.  
  • The scoring function can't be 'gamed'  
  • It shouldn't make tournament administration any harder. Rules already have to exist for double forfeits.

 
I also think it is aesthetically pleasing for the game of arimaa. Here is a simple definition of arimaa which is very similar to the first line on the arimaa homepage:
   'Arimaa is a race against your opponent to force a rabbit to the other side'
Why not change this to:
   'Arimaa is a race against your opponent and the clock to force a rabbit to the other side'
 
I think it nicely solves several of the example problems in this thread too. Why should a game where both players have placed all their rabbits on the 4th row be a victory for one of them? Neither of them deserve to win. You only deserve to win if you actually win within the allotted time
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Hippo
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Re: Replace the Scoring Function
« Reply #50 on: Apr 30th, 2013, 6:34pm »
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on Apr 30th, 2013, 5:09pm, Brendan_M wrote:
There is another option - the result of a game that ends on time is a loss for both players
 
This satisfies the following criteria:
  • The game will end in a known amount of time
  • The result of the game must be consistently reproducible.  
  • The result of the game must be completely in control of the players.  
  • The scoring function can't be 'gamed'  
  • It shouldn't make tournament administration any harder. Rules already have to exist for double forfeits.

 
I also think it is aesthetically pleasing for the game of arimaa. Here is a simple definition of arimaa which is very similar to the first line on the arimaa homepage:
   'Arimaa is a race against your opponent to force a rabbit to the other side'
Why not change this to:
   'Arimaa is a race against your opponent and the clock to force a rabbit to the other side'
 
I think it nicely solves several of the example problems in this thread too. Why should a game where both players have placed all their rabbits on the 4th row be a victory for one of them? Neither of them deserve to win. You only deserve to win if you actually win within the allotted time

 
Yes, I like this idea. Except in that case rating systems could be confused. Is this problem of rating systems? The sum of ratings should be maintained.
« Last Edit: Apr 30th, 2013, 6:36pm by Hippo » IP Logged

Fritzlein
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Re: Replace the Scoring Function
« Reply #51 on: Apr 30th, 2013, 8:05pm »
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on Apr 30th, 2013, 5:09pm, Brendan_M wrote:
There is another option - the result of a game that ends on time is a loss for both players

This would unfortunately give an incentive for stalling, on the theory "I'm not going to win, but I'm at least going to take the other guy down with me."  Players might choose to pass up a desperate counter-attack, might give up hopes of a swindle, in exchange for the most tortuous defense that is certain not to win.
 
Zero-sum games have different incentives than games which are not zero-sum.  In the former, by definition the only way you can hurt the other player is to help yourself.  In the latter you can choose to hurt the other player even if doing so hurts you too.
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