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Topic: Comment for Game 61712 (Read 1006 times) |
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Fritzlein
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Comment for Game 61712
« on: Oct 27th, 2007, 6:19pm » |
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Yes, Arimaanator, although chessandgo had an overwhelming position after winning horse plus cat for just a dog, I believe that I was winning after 47w, and had caught up a couple of moves before that. On 48w perhaps I could have centralized my elephant with the last two steps instead of bringing the rabbit to d3, but I think my actual move was not too bad. After that it gets ridiculously complex, and I need a bot to analyze for me.
On 49w I should have played 49w Ec4e Ed4e rf4n Ee4e, because it not only slows down the silver rabbit, it threatens goal in 8 steps with my g3-rabbit, compared to goal in 9 steps for chessandgo in the east. However, if Silver makes the proper counter-threat in the east, it just turns into a rabbit trade with the remaining position still exceedingly tense. I think I still have an advantage after the trade, but it is very easy for either side to go astray.
I thought my death was assured after my mistaken 49w and chessandgo's 49b. Bomb, however, found a move 50w that gives me new life, and apparently forces goal.
50w rf4n Ee4e Ch3w rh4s
. 50b cg5n rc7w rb7n rb6n
. . 51w rf5w Ef4n Ef5e ra4e (+-)
. 50b rf5w re5w cg5n cg6e
. . 51w Ra4n Rg4n Rg5n Ef4n
. . . 51b rc7e rd7e re7e rf7e
. . . . 52w Cg3n Cg4e Rh5w Rg6w (+-)
. 50b cg5n Rh5w rc7e ra6s
. . 51w rf5w Ef4n Rg5e Ef5e
. . . 51b rd7e re7e rf7e cg6e
. . . . 52w Eg5n Rg4n Rg5w Rf5n (+-)
. 50b ee3n ee4n ee5n cg5n
. . 51w rf5w Ef4n Ef5e Rh5n
. . . 51b ee6n ee7e ef7e eg7e
. . . . 52w cg6w cf6x Eg5n Rg4n Rg5w
. . . . . 52b dc5e re5s dd5e rc7w
. . . . . . 53w Ra4n Ra5e Rb5n Rc4n (+-)
But then, just when I was about to announce this a probably a forced goal for Gold, Bomb produced the following defense for Silver: 50b ra6s cg5n rc7e rd7e. As chessandgo and I were chatting after the game, we agreed that if Silver must bring over the c7-rabbit to help defend, Gold must be winning. But we were wrong! The crossing rabbit apparently slows down the Gold gold threat in the east just long enough for Silver to break through in the west. Plus the Silver rabbits on h3 and f5 remain threatening. For example
. 50b ra6s cg5n rc7e rd7e
. . 51w Rh5n Rg4e Rh4n Rh6n
. . . 51b cg6e ra5e rb5s dc5w (-+)
. . 51w rf5w Ef4n Ef5e Rh5n
. . . 51b re7e rf7e rg7e re5e (-+)
. . 51w rf5w Ef4n Rg4n Rh5n
. . . 51b re7e rf7e rg7e ee3n
. . . . 52w Rg5e Ef5e cg6w cf6x Eg5n
. . . . . 52b ee4e ef4e eg4n Cg3n (-+)
. . 51w rf5w Ef4n Rg4w Rh5n
. . . 51b cg6n ra5e rb5s dc5w (-+)
So perhaps I didn't miss a win on 50w after all. One thing is clear: Bomb would have won this endgame as either Gold or Silver against either me or chessandgo. It is bizarre that in chess, the endgame was the last refuge of the human grandmasters against the computers, whereas in Arimaa the endgame is the first territory conquered by computers. If the bots ever get good enough to survive the opening and middlegame, and reach a playable endgame, it is all over for humans and the Arimaa Challenge.
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chessandgo
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Re: Comment for Game 61712
« Reply #1 on: Oct 28th, 2007, 5:02am » |
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Thanks for posting this analysis, Karl. If I were not convinced before that this endgame was tricky, now I am 
Additionnally, I should have played 49b with rc7w as last step instead of ra6s ; I think it forces goal in 2 (in any case, it threatens goal in one less step, as my a-rabbit can't leave the a-file ... ).
Indeed Karl, bots are super strong in extremely sharp positions, like this one, where goal is forced for one side in almost all varaiations, but reaching the start of the endgame is not enough ; a bot would still have to play the endgame starting on 23w as well as you did, playing actively and creating potential goal threats ... and they're far from being able to do that, if I am not mistaken So I am not too much worried for the challenge at the moment ... that is, unless bots get strong at go within the next decade, which I sincery doubt ...
All in all, I'd rather say that endgame is the weakest spot of bots for the moment, but maybe making them (especially Bomb) more prone to advancing rabbits as strategical moves would take care of this ...
As for arimanator's comment, I would rather call Karl's winning (?) position in the end of the endgame a "clear tactical advantage" rather than a "clear positionnal advantage", but I guess it's a matter of point of view. Before 21w (or maybe rather before 19w), the game was about equal, with a very slight advantage for Karl in the opening.
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omar
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Re: Comment for Game 61712
« Reply #2 on: Oct 28th, 2007, 10:47pm » |
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This end game position was very sharp and every step was very critical. I think what made this end game so sharp was that many of the stronger pieces had been traded off but there were still many rabbits left. Bots will definitely play better than humans in such sharpe positions. I think the key for humans would be to avoid trading down major pieces and not get into such end games. The key for bots may be to try for such end games. So an interesting question becomes is it possible for one to force a trade down of the stronger pieces or can the opponent prevent it. I think it's possible to force a trade down of rabbits, but a forced trade down of the major pieces it probably not possible. But it needs to be tested though.
49w Rg3n Rg4n Ch3w Cg3n looks interesting. Almost seems like it can lead to a win for gold.
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Fritzlein
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Re: Comment for Game 61712
« Reply #3 on: Oct 28th, 2007, 11:31pm » |
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on Oct 28th, 2007, 10:47pm, omar wrote:| 49w Rg3n Rg4n Ch3w Cg3n looks interesting. Almost seems like it can lead to a win for gold. |
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Wow, that does look powerful. Not only did I miss it, so did Bomb. I'll have to check whether it is actually forced goal, but I won't be surprised if it is. Nice find, Omar!
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chessandgo
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Re: Comment for Game 61712
« Reply #4 on: Oct 29th, 2007, 3:30am » |
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Interesting move, Omar. I can only see 49b ch6w Rg5w cg6s db5n for silver, and then I'm completely unable to predict the outcome ...
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Fritzlein
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Re: Comment for Game 61712
« Reply #5 on: Oct 29th, 2007, 9:51pm » |
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Chessandgo, your move is the one that Bomb recommends, after which there is a fairly forcing continuation:
49w Rg3n Rg4n Ch3w Cg3n
49b ch6w Rg5w cg6s db5n
50w Ra4n Rb4n Rb5e Rc5e
50b rc7e rd7s ee3n ee4n
After which it remains very unclear. I rather like grabbing a rabbit with 51w Ec4e Ed4e rf4s rf3x Ee4e, but I don't know if that is enough to win, and it does somewhat open up the west.
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omar
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Re: Comment for Game 61712
« Reply #6 on: Oct 29th, 2007, 11:39pm » |
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Pushing the dog to the side with the elephant seems interesting; threatens to unfreeze and advance the d5 rabbit.
51w Ec4n Ec5w db6w Eb5n
51b Rf5n Rf6x ee5e rf4w ef5w
52w Rd3n Re2n Rd5w Rc5n
52b ee5n ee6n ee7w ed7w
53w Cg4w Cf4e re4e Re3n
51w Ec4n Ec5w db6w Eb5n
51b ee5s ee4w Ra5s da6s
52w Eb6s Eb5e Rd5e Re5n
52b ed4e ee4n ra7s ra6e
53w Ec5e rd6n Ed5n Re6n
53b ee5n Re7e ee6n rd7w
54w rf4s rf3x Cg4w Rf5n Rf7n Rf6x
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Fritzlein
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Re: Comment for Game 61712
« Reply #7 on: Oct 30th, 2007, 8:30am » |
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on Oct 29th, 2007, 11:39pm, omar wrote:Pushing the dog to the side with the elephant seems interesting; threatens to unfreeze and advance the d5 rabbit.
51w Ec4n Ec5w db6w Eb5n |
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Bomb finds the ingenious reply 51b ee5s Rd5e ee4s Rd4s, which puts a stop to Gold's goal threat while restoring Silver's goal threat.
Meanwhile in the line
49w Rg3n Rg4n Ch3w Cg3n
49b ch6w Rg5w cg6s db5n
50w Ra4n Rb4n Rb5e Rc5e
50b rc7e rd7s ee3n ee4n
51w Ec4e Ed4e rf4s rf3x Ee4e
Bomb believes that 51b db6w ra7e rb7s rb6s can be adequately met by 52w Rd3n Rd4w Rc4w Ef4w, because 52b da6e Ra5n rb5w ra5s loses to 53w Rb4n Ee4w Ed4w Ec4w.
I am starting to believe that Gold has a forced win after all starting with 49w Rg3n Rg4n Ch3w Cg3n, although it is probably misleading to call anything "forced" that is so complicated I can barely see through it with the help of a computer, and not at all on my own.
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| « Last Edit: Oct 30th, 2007, 8:47am by Fritzlein » |
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omar
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Re: Comment for Game 61712
« Reply #8 on: Oct 31st, 2007, 8:15am » |
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Quote:
Bomb finds the ingenious reply 51b ee5s Rd5e ee4s Rd4s, which puts a stop to Gold's goal threat while restoring Silver's goal threat.
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Yeah, that does stop it. Maybe it might be better for Gold to trade down some rabbits first, since Gold has more rabbits. How about:
51w rf4s rf3x Cg4w Cf4e Ec4n
threatening
52w Ec5w db6e Eb5n Ra5n
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omar
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Re: Comment for Game 61712
« Reply #9 on: Nov 2nd, 2007, 11:30pm » |
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Adding this link to make it easy to get to the game:
http://arimaa.com/arimaa/games/showGame.cgi?gid=61712&s=w
Has anyone found a good defense for silver after the line:
49w Rg3n Rg4n Ch3w Cg3n
49b ch6w Rg5w cg6s db5n
50w Rb4n Ra4n Rb5e Rc5e
50b ee3n ee4n rc7e rd7s
51w rf4s rf3x Cg4w Cf4e Ec4n
Threatening:
52w Ec5w db6e Eb5n Ra5n
I can't seem to find one and am starting to think
that maybe gold can win from the position after 51w.
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| « Last Edit: Nov 2nd, 2007, 11:31pm by omar » |
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Fritzlein
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Re: Comment for Game 61712
« Reply #10 on: Nov 3rd, 2007, 8:38pm » |
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on Nov 2nd, 2007, 11:30pm, omar wrote:Adding this link to make it easy to get to the game:Has anyone found a good defense for silver after the line:
49w Rg3n Rg4n Ch3w Cg3n
49b ch6w Rg5w cg6s db5n
50w Rb4n Ra4n Rb5e Rc5e
50b ee3n ee4n rc7e rd7s
51w rf4s rf3x Cg4w Cf4e Ec4n |
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It seems that Gold has a winning endgame after this. Silver can hardly do better than take a rabbit with
51b Rf5n Rf6x cg5w cf5e xxxx
with a final step of rabbit or dog to a6. In either case the Gold elephant can generate a goal threat in the west which the Silver elephant can't defend due to the threat of the central Gold rabbits.
In short, it appears that 49w Rg3n Rg4n Ch3w Cg3n is indeed a forced win, although far beyond my ability to find in a live game, and difficult to prove in analysis even with the help of computers.
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omar
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Re: Comment for Game 61712
« Reply #11 on: Nov 4th, 2007, 11:20pm » |
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Yes, it definitely would not be possible to figure out such a line in a live game. It took us several attempts to find it now. But it is interesting to know that there was a chance for gold to win and Arimantor's hunch that gold had a positional advantage at some point was right.
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