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        Arimaa >> General Discussion >> forced goals in 4 or more?
        
(Message started by: chessandgo on Feb 26^th, 2010, 1:40pm)

Title: forced goals in 4 or more?
Post by chessandgo on Feb 26^th, 2010, 1:40pm

Dear all,

following aaaa's suggestion, I would like to post here positions where I think there is a forced goal in 4 (or more) to check my analysis before releasing my book. I don't know whether these positions are bot tractable (I fear not, but I'd love to check), and I'm interested in human analysis as well.

1) game 57508 Fritzlein-chessandgo from the Postal Tournament 2007, move 34s

http://arimaa.com/arimaa/games/showGame.cgi?gid=57508 to replay

On 34s, I think the game move forces goal in 4, and that is is the single forced goal.

2) game 114237, Fritzlein-chessandgo, Postal Tournament 2009, move 30s.

http://arimaa.com/arimaa/gameroom/showGame.cgi?gid=114237 to replay

Imagine silver plays 30s de8e rc8ee df8e. I the game comment I recently wrote that I thought 31g Hg6n Rg5n Cg4n Rg3n was a goal in 4, in view of 31s re8e rc7e de7n rd7e 32g dg8e Hg7n Rg6n Cg5n 32s Cg6s hf6e Rg7e hg6n 33g hg7s Mf7e rf8s Hg8w, which I thought forced a goal in 1. But I realized just tonight that silver could simply play hg6w rh6w Rh7s dh8s, preventing goal.

So I wondered about 31g Hg6ne Rg5n Cg4n instead. I can only see for silver: 31s re8e rc7e de7n rd7e 32g Rg6n Rg3n Cg5n Rg4n 32s dg8e rf8e de8e cb6n 33g df8w Mf7n Rg7w Hh7w 33s cb7een ra7e 34g Ee6w re7ss Ed6e 34s rb7eee x 35g Ee6w re7s Ed6ne 35s re6w hf6w Rf7s x 36g Rf6n Cg6w Hg7s rg8s, forcing a goal at last.

Actually it even looks like 33g re7w Mf7w Rg7w Hh7w 33s cb7neee (33s df8w rg8w dh8w cb7e 34g dg8e Hg7n Rf7e Me7e forces goal) 34g rd7s Me7w Rf7w Hg7w 34s ce8w df8w rg8w x 35g cd8w Md7n Re7w Hf7w forces goal one move earlier than in the above variation. [From the former varation one can also transpose into this latter variation on 32g]

I have the distinct feeling that I'm getting carried away here :) Can anyone see a hole in the above goal attack? Can anyone see an easier forced goal for gold after this alternative 30s move? Can a bot see something? I think that gold can do at least as well against other defenses on 30s besides flipping the Rg5 away; does someone see a better other 30s defense not losing the hf6?

Cheers

Jean

Title: Re: forced goals in 4 or more?
Post by jdb on Feb 28^th, 2010, 7:03am

on 02/26/10 at 13:40:10, chessandgo wrote:

Dear all,

1) game 57508 Fritzlein-chessandgo from the Postal Tournament 2007, move 34s

http://arimaa.com/arimaa/games/showGame.cgi?gid=57508 to replay

On 34s, I think the game move forces goal in 4, and that is is the single forced goal.

Jean

35g Rd3e Rc3e Mc4s Rb1w

I think this delays the end for a bit longer.

Title: Re: forced goals in 4 or more?
Post by chessandgo on Feb 28^th, 2010, 7:36am

on 02/28/10 at 07:03:15, jdb wrote:

35g Rd3e Rc3e Mc4s Rb1w

I think this delays the end for a bit longer.

Oh, this looks correct. After 35s mc2we Ra2e rb3s I think that: 36g Rb4e Rb3n Mc3ww 36s Rb2n mc2w Rd3w dd4s goals in 1. Or 36g Rb3w Mc3w x x 36s mc2s ee2ww goals on next move as well. But 36g Rb4e Rb3n Mc3w (Rc4n or Cf1w) seems to hold one move longer. 36s mc2s Rb2e mc1wn 37g Mb3we ra3n (Rc5n or Ef4s depending on 36g) 37s ra3s ha4s Rb4w (rc8w or ee2w depending on 37g) forces goal on next move.

Was this what you were thinking about with your 35g jdb? Am I missing a better defense? A better offense? Would the original position be a goal in 5? I guess that'd be bad news for a bot proof.

Title: Re: forced goals in 4 or more?
Post by jdb on Mar 3^rd, 2010, 7:02pm

http://arimaa.com/arimaa/games/showGame.cgi?gid=136513 to replay
move 48b

Title: Re: forced goals in 4 or more?
Post by chessandgo on Mar 9^th, 2010, 3:37am

do you think this forced goal is unique jdb? Gold's goal defense is so sparse that it looks like many other moves might goal in four as well? Like 48s db7s ec7w rb5ws?