Arimaa Forum
        (http://arimaa.com/arimaa/forum/cgi/YaBB.cgi)
      

        Arimaa >> General Discussion >> Endgame Puzzle 7
        
(Message started by: jdb on Apr 5th, 2011, 8:45am)
Title: Endgame Puzzle 7
Post by jdb on Apr 5th, 2011, 8:45am
Silver to play and win

1w Db1 Ra2 Ca5
1b da1 ra3
2w pass

http://arimaa.com/arimaa/games/planGame.cgi

Hint: There are only two choices for the first move, one works the other does not.
Title: Re: Endgame Puzzle 7
Post by Fritzlein on Apr 5th, 2011, 11:23am
My first thought is that I have no idea.  I tried a few lines and find it much less obvious than Puzzle 6.  On the other hand, it is so much fun to hide text with the background color, I simply can't resist!  It makes me feel all special, like I have a big secret to whisper.  But maybe nobody will fall for this trap.  :)
Title: Re: Endgame Puzzle 7
Post by chessandgo on Apr 5th, 2011, 1:40pm
Haha! I've fallen for it.
Title: Re: Endgame Puzzle 7
Post by chessandgo on Apr 5th, 2011, 1:43pm
Great, post count +1. So I've got:

2s Ra2ee da1ne 3g Db1w Ca5ess 3s Rc2e db2e, and I think silver wins by pushing Gold's Rabbit to e3 on the next move. When I started to look at the position I went "wow, no way!". Rabbit advancement, rabbit advancement :)
Title: Re: Endgame Puzzle 7
Post by mistre on Apr 5th, 2011, 3:03pm
I think I might have it! See below for my guess.

[color= #AFC6DB ]
2s Ra2e da1n Rb2e da2e
3g Ca5s Ca4e Cb4s Db1w
3s Rc2e db2e
4g Da1n Cb3n Cb4e
4s Rd2n dc2e Rd3e dd2n
5g ra3e Da2n rb3n Da3e
5s Re3e Rf3x dd3e
[/color]
Title: Re: Endgame Puzzle 7
Post by jdb on Apr 5th, 2011, 3:52pm
This puzzle is much more difficult than I intended.

Both attempts so far need to address the subtle
4g Da1e Db1n !!!
Title: Re: Endgame Puzzle 7
Post by robinz on Apr 5th, 2011, 4:05pm
[color= #AFC6DB ]I had a different move for 3s - I flip the cat to B1 instead. Is this any good? (I haven't found a refutation yet, but I wouldn't swear there isn't one - as you say, this is a tougher position than it looks!)[/color]
Title: Re: Endgame Puzzle 7
Post by Eltripas on Apr 5th, 2011, 9:00pm

on 04/05/11 at 16:05:44, robinz wrote:
[color= #AFC6DB ]I had a different move for 3s - I flip the cat to B1 instead. Is this any good? (I haven't found a refutation yet, but I wouldn't swear there isn't one - as you say, this is a tougher position than it looks!)[/color]


What's whit the people putting their answers in that color?

Edit: mmm the problem seems to be that you put a space after color= (color= #AFC6DB), that causes some browsers to put that text in a very visible green color,  if you don't put the space it works fine (color=#AFC6DB).
Title: Re: Endgame Puzzle 7
Post by Hippo on Apr 6th, 2011, 3:52am

on 04/05/11 at 21:00:25, Eltripas wrote:
What's whit the people putting their answers in that color?

It's almost invisible in some browsers, but clearly visible in others ... please use exact colors mentioned in separete thread.

BTW: I have not found a way to unhide on experia, yet ... expect start quotting ...
Title: Re: Endgame Puzzle 7
Post by ginrunner on Apr 6th, 2011, 1:43pm
easily the hardest one yet ... I just now finally got it

moves?Ra2e da1n Rb2n Da2e
Db1w Ca5e Cb5e Cc5s
Rb3n db2n Rb4n db3n
Da1n
Rb5n db4n Rb6e Rc6x db5n


edit: if the cat moves differently then there is a completely different line that I just found where gold is again forced to make certain moves but puzzles like this can go in a few different direction.
Title: Re: Endgame Puzzle 7
Post by mistre on Apr 6th, 2011, 3:59pm
Ginrunner,

Doesn't 3g Ca5s Ca4e ra3n Rb3w kill your plan?

Don't get me wrong - you still might have the right 2s.  This one is so complicated!
Title: Re: Endgame Puzzle 7
Post by ginrunner on Apr 6th, 2011, 4:57pm
that was the different line I said in my edit. i still think it wins ... let me refind the line in that case.

edit: yes every line I have so far leads to a win due to two things but there are so many different paths from there that I could be wrong (I don't think I am). more:That cat move eventually leads to Ra3 Db3 ra4 dc5. Then the advanced rabbit has a major advantage from the 2 decent moves gold can do after that. Gold can not make a threat without opening up a threat but again this line is fuzzier.
Title: Re: Endgame Puzzle 7
Post by mistre on Apr 6th, 2011, 7:30pm
But if there is only one solution - doesn't it require there to be only one winning line?

JDB, can you please verify?
Title: Re: Endgame Puzzle 7
Post by jdb on Apr 6th, 2011, 8:11pm

on 04/06/11 at 19:30:57, mistre wrote:
But if there is only one solution - doesn't it require there to be only one winning line?

JDB, can you please verify?


Since this puzzle is difficult, I'll give some clarification.

If gold plays the longest defence, silver wins on 9b.

On silver's first and second turn, there is only one winning move.

On gold's first turn, there is only one move that is a strong defense.

After that there are more possibilities.
Title: Re: Endgame Puzzle 7
Post by mistre on Apr 6th, 2011, 9:39pm
So in order to solve - we need to find the line that silver wins on 9b?
Title: Re: Endgame Puzzle 7
Post by Fritzlein on Apr 7th, 2011, 1:55am

on 04/06/11 at 21:39:33, mistre wrote:
So in order to solve - we need to find the line that silver wins on 9b?

Particularly when there are very few reasonable choices for the first move, the justification of the chosen move has to count for more than the move itself, doesn't it?  When jdb said that there were only two reasonable choices for the first move, I was very tempted to pick one and say, "I solved this in no time!"   I mean, I would have had a fifty percent chance of being a genius, right?  ;D
Title: Re: Endgame Puzzle 7
Post by chessandgo on Apr 7th, 2011, 8:38am

on 04/05/11 at 15:52:29, jdb wrote:
Both attempts so far need to address the subtle
4g Da1e Db1n !!!


Ahaa, cute defense.
Title: Re: Endgame Puzzle 7
Post by chessandgo on Apr 7th, 2011, 8:39am
I still can't see how Gold defends for as long as 9s. Here is what I have:

2s Ra2ee da1ne 3g Db1w Ca5ess 3s Rc2e db2e 4g Da1e Db1n 4s Rd2ne dc2en 5g Cb2eee Re3n [5g Cb2eeee loses immediately to dd3nww] 5s dd3nw Re4w, and I don't see any solid defense. For example:

- 6g ra3n Cb3w De2wn 6s Rd4nn dc4en
- 6g "Flip the ra3 to b4" 6s rb4wn dc4w Rd4w
- 6g Cb3s ra3e De2wn 6s dc4w Rd4w rb3ws 7g ra2n Cb2w Dd3w Rc4e 7s db4e 8g ra3en Ca2ne 8s immo. Urgh, that's 8s, not 9s, I'm still missing things.

Btw, it would be awesome if the planGame.cgi window used the V2 client and not the old client. That would allow us to play the moves in the plan window and then copy-paste the variations. I would stop confusing east and west every couple moves (and at last understand Hippo's variations, haha).
Title: Re: Endgame Puzzle 7
Post by Hippo on Apr 7th, 2011, 9:09am

on 04/07/11 at 08:39:10, chessandgo wrote:
I would stop confusing east and west every couple moves (and at last understand Hippo's variations, haha).


Yes solution using the tree analyses tool would be nice.
BTW: This one Looks so hard that I prefere codding my bot to solving it (myself). Sorry Fritzlein for repeating the joke. I have written nothing concerning this puzzle so I hope there is nothing confusing for Jean :).
Title: Re: Endgame Puzzle 7
Post by jdb on Apr 7th, 2011, 9:14am
@chessandgo
6g Cb3s Cb2w De2w Dd2n
Title: Re: Endgame Puzzle 7
Post by mistre on Apr 7th, 2011, 10:07am

on 04/07/11 at 09:14:19, jdb wrote:
@chessandgo
6g Cb3s Cb2w De2w Dd2n


Everything that I can find after that 6g is a loss for silver! I honestly don't know if we even have the first move right -  >:(
Title: Re: Endgame Puzzle 7
Post by chessandgo on Apr 7th, 2011, 12:37pm

on 04/07/11 at 09:14:19, jdb wrote:
@chessandgo
6g Cb3s Cb2w De2w Dd2n


uh oh :)
Title: Re: Endgame Puzzle 7
Post by rbarreira on Apr 7th, 2011, 2:09pm
Encrypted spoiler (I don't know if it's really correct):


Quote:
1j Qo1 En2 Pn5
1o qn1 en3
2j cnff
2o En2r qn1a Eo2r qn2r
3j Pn5r Po5f Po4f Qo1j
3o qo2j Po3f Po2f qn2r
4j Po1r Qn1a Ep2r Pp1r
4o qo2r qp2f qp1a Pq1j
5j en3r Qn2a eo3a Qn3r
5o Eq2a qp2r Eq3r qq2a
6j Pp1r Pq1r Pr1r Ps1a
6o qq3a Er3j qq4j Eq3a
7j Ps2j Pr2a Pr3a Pr4a
7o eo4j Eq4f qp4r
8j Pr5r Ps5r Pt5f Pt4f
8o qq4j Eq3a qp4j Eq4j
9j Qo3j en4a Qn3a Pt3j Ps3k
9o Ep4f Ep3k qo4r qp4j qo4r
Title: Re: Endgame Puzzle 7
Post by novacat on Apr 7th, 2011, 8:10pm
My first move for silver is the same as ginrunner's.  It also matches jdb's hints (three forced moves and then several options for gold that all lose).

Here's my solution:
1g  Db1 Ra2 Ca5
1s  da1 ra3
2g  pass
2s  Ra2e da1n Rb2n da2e
3g  Ca5s Ca4e ra3n Rb3w
3s  db2n
4g  Db1n Db2e (for longest defense, several options available otherwise)
4s  Cb4n db3n
5g  Dc2e Db2n
5s  Cb5e db4n Cc5n db5e
6g  Db3n (once again several options, some lose faster than others)
6s  dc5w db5w
7g  Db4n ra4e rb4e Db5s
7s  da5e db5e rc4e dc5s
8g  Db4s Db3s Db2e Dc2e
8s  rd4e re4e dc4w db4w
9g  Dd2n
9s  rf4e rg4s rg3s rg2s
Title: Re: Endgame Puzzle 7
Post by Hippo on Apr 8th, 2011, 8:59am
JDB@:
Is position da5 ra4 Db4 Ra3 mutual zugzwang?
What about ra5 db5 Ra4 Db4?

Oh finding mutual zugzwang is much easier than I expected ... ra5 Ra4 is an easy example:).
Title: Re: Endgame Puzzle 7
Post by jdb on Apr 8th, 2011, 9:12am
@novcat

A nice piece of analysis, but

7g Db4e ra4e Dc4n rb4e

and gold wins.
Title: Re: Endgame Puzzle 7
Post by ginrunner on Apr 8th, 2011, 12:41pm
Did we prove me wrong? cause I can't figure out if I got it or not.
Title: Re: Endgame Puzzle 7
Post by jdb on Apr 8th, 2011, 1:35pm

on 04/08/11 at 12:41:12, ginrunner wrote:
Did we prove me wrong? cause I can't figure out if I got it or not.


2s Ra2e da1n Rb2n da2e
3g Ca5s Ca4e ra3n Rb3w

See novcat's posting for an analysis of this position.
Title: Re: Endgame Puzzle 7
Post by ginrunner on Apr 8th, 2011, 4:48pm

on 04/08/11 at 13:35:23, jdb wrote:
2s Ra2e da1n Rb2n da2e
3g Ca5s Ca4e ra3n Rb3w

See novcat's posting for an analysis of this position.


here is my full solution DO NOT CLICK IF YOU DON'T WANT TO SEE A SPOILER
http://arimaa.com/arimaa/games/planGame.cgi?sid=1346699
Title: Re: Endgame Puzzle 7
Post by jdb on Apr 8th, 2011, 7:31pm

on 04/08/11 at 16:48:03, ginrunner wrote:
here is my full solution DO NOT CLICK IF YOU DON'T WANT TO SEE A SPOILER
http://arimaa.com/arimaa/games/planGame.cgi?sid=1346699


5g Db3n
Title: Re: Endgame Puzzle 7
Post by ginrunner on Apr 10th, 2011, 2:50pm
I think I am trying too hard to make my solution correct. Even with that move I still only find wins for gold due to such an advanced rabbit.
Title: Re: Endgame Puzzle 7
Post by jdb on Apr 12th, 2011, 8:56am
Special congratulations to robinz for finding the correct solution!
Title: Re: Endgame Puzzle 7
Post by robinz on Apr 12th, 2011, 9:25am
Thanks jdb, but I think I got lucky to stumble across the solution which turned out to be correct. I certainly hadn't analysed it in the necessary detail to prove to myself that it was correct, let alone found all the subtleties which make other lines fail  :)
Title: Re: Endgame Puzzle 7
Post by Tuks on Jun 6th, 2011, 7:22am
solved in 1 minute and 5 seconds, sorry, its a problem i have, its not whether i can solve it, its how fast i can, haha

well, when i say solved it, its hard to go through all the possibilities, but i got into a good position that i decided was won :) either by elimination or goal


Arimaa Forum » Powered by YaBB 1 Gold - SP 1.3.1!
YaBB © 2000-2003. All Rights Reserved.