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Topic: Reverse puzzles and impossible positions (Read 4017 times) |
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ocmiente
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Re: Reverse puzzles and impossible positions
« Reply #15 on: May 24th, 2010, 8:18pm » |
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No, I don't think so.
There is another... and another... (just two main others that I can think of. Try starting the elephant at e6 or something else at d5
<EDIT>
Oh... wait.. forgot about that cat... just a minute...
<EDIT>
I think you're right...
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| « Last Edit: May 24th, 2010, 8:25pm by ocmiente » |
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Isaac Grosof
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Re: Reverse puzzles and impossible positions
« Reply #16 on: May 24th, 2010, 8:22pm » |
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Yeah, that cat is vital. I still think it's unique.
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Sorry about that one thing.
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Fritzlein
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Re: Reverse puzzles and impossible positions
« Reply #17 on: May 25th, 2010, 6:58am » |
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on May 24th, 2010, 5:33pm, FireBorn wrote:I don't think this one's possible:
Code:
+-----------------+
8| . . . . . . . . |
7| . . . . . . . . |
6| . . x . . x . . |
5| R R r R R r R R |
4| r r R r r R r r |
3| . . x . . x . . |
2| . . . . . . . . |
1| . . . . . . . . |
+-----------------+
a b c d e f g h
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It looks possible with a c-file or f-file rabbit having been pushed into position to complete the two rabbit lines, and then the piece(s) that enabled the push committing suicide.
<EDIT>
Oh, maybe not, because there must have been a friendly piece keeping the rabbit safe on the trap before the push, and then there is no place for that piece to suicide later. Subtle point!
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| « Last Edit: May 25th, 2010, 7:17am by Fritzlein » |
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Fritzlein
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Re: Reverse puzzles and impossible positions
« Reply #18 on: May 25th, 2010, 7:12am » |
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on May 24th, 2010, 8:22pm, 722caasi wrote:| Yeah, that cat is vital. I still think it's unique. |
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I, too, can't find a second solution. Nice puzzle, thanks! But Silver could also have bought about the terminal position in many ways, so technically Gold's last move could have been many, many different things if it was Silver who ended the game. I guess the question, "What did Gold just play?" implies that Gold "just" played, meaning Silver hasn't any time to play since then, but to leave no room for pedantic quibbling, one might instead frame the question as, "Gold made this game's last move. What was it?"
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Hippo
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Re: Reverse puzzles and impossible positions
« Reply #19 on: May 25th, 2010, 11:26am » |
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I have counted 216222 solutions to the Rd8 ee8 cd6 puzzle (not counting the order of steps).
The last puzzle has the only solution, switched all pieces cannot be achieved and two switched rows of rabbits except the f,c ones as well.
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| « Last Edit: May 25th, 2010, 11:44am by Hippo » |
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FireBorn
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Re: Reverse puzzles and impossible positions
« Reply #20 on: May 25th, 2010, 12:54pm » |
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I don't think this one's possible either:
Code:
+-----------------+
8| . . . . . . . . |
7| . . D . . H . . |
6| . d x . . x h . |
5| . . . . . . . . |
4| . . . . . . . . |
3| . m x . . x c . |
2| . . M . . C . . |
1| . . . . . . . . |
+-----------------+
a b c d e f g h
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FireBorn
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Re: Reverse puzzles and impossible positions
« Reply #21 on: May 25th, 2010, 1:02pm » |
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Neither is this one:
Code:
+-----------------+
8| . . . . . . . R |
7| . . . . . . . . |
6| . . x . . x . . |
5| . . . . . . . . |
4| . . . . . . . . |
3| . . x . . x . . |
2| . . . . . . . . |
1| r . . . . . . . |
+-----------------+
a b c d e f g h
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This one is possible:
Code:
+-----------------+
8| . . . . . . . R |
7| . . . . . . . . |
6| . . x . . x . . |
5| . . . . . . . . |
4| . . . . . . . . |
3| . . x . . x . . |
2| . . . . . . . . |
1| . . r . . . . . |
+-----------------+
a b c d e f g h
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But this one is not:
Code:
+-----------------+
8| . . . . . . . R |
7| . . . . . . . . |
6| . . x . . x . . |
5| . . . . . . . . |
4| . . E . . . . . |
3| . . x . . x . . |
2| . . . . . . . . |
1| . . r . . . . . |
+-----------------+
a b c d e f g h
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Nor this one:
Code:
+-----------------+
8| . . . . . . . R |
7| . . . . . . . . |
6| . . x . . x . . |
5| . . . . . . . . |
4| . . . . . . . . |
3| . . x . . x . . |
2| . . C . . C . . |
1| . . r . . r . . |
+-----------------+
a b c d e f g h
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| « Last Edit: May 25th, 2010, 1:03pm by FireBorn » |
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FireBorn
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Re: Reverse puzzles and impossible positions
« Reply #22 on: May 25th, 2010, 1:25pm » |
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I'm trying to come up with one involving immobilization but for the life of me I can't
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Hippo
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Re: Reverse puzzles and impossible positions
« Reply #23 on: May 26th, 2010, 8:50am » |
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Twin puzzles:
 | | | That was a strange game. | That was a strange game. | | Now it's Silver's turn and Silver is winning. | Now it's Gold turn and Gold is winning. | | Explain why. | Explain why. |
Would the solution differ for the other players turn?
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| « Last Edit: May 26th, 2010, 10:28am by Hippo » |
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leo
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Re: Reverse puzzles and impossible positions
« Reply #24 on: May 26th, 2010, 9:17am » |
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You guys sure are inventive! 
Hippo: that last one of yours is most strange, whose turn is it?
EDIT: OK, you updated your post. I'll try to solve the puzzles.
FireBorn: yeah, immobilizations and forced moves should give some good puzzles
Fritzlein: retrograde analysis, will remember the term ^^
722caasi: because of my upcoming web domain change the board picture urls will soon become invalid. you can either save them and upload them on imageshack or such -- or change the urls when the transfer is done: see this thread
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| « Last Edit: May 26th, 2010, 10:09am by leo » |
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FireBorn
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Re: Reverse puzzles and impossible positions
« Reply #25 on: May 26th, 2010, 12:46pm » |
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@Hippo:
My understanding of the repeat-rules is fuzzy, but I think in the first one Silver is winning because he can shuffle his f8 rabbit back and forth while Gold has to keep coming up with new board positions, meaning his h6 rabbit will eventually have to move to g6, freeing Silver's cat, and once it's free Silver can block off that corner of the board with his rabbits and decimate Gold's rabbits with his cat.
Similar situation if it's Gold to move, except silver will be forced to move a rabbit out of the way, allowing Gold to goal next move.
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Hippo
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Re: Reverse puzzles and impossible positions
« Reply #26 on: May 26th, 2010, 2:24pm » |
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Try to show possible last moves preceding the position.
They are more natural for the case Silver is winning. And a bit confusing for the case Gold is winning.
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| « Last Edit: May 26th, 2010, 2:24pm by Hippo » |
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Isaac Grosof
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Re: Reverse puzzles and impossible positions
« Reply #27 on: May 26th, 2010, 2:34pm » |
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Hippo: The last move could just have been a suicide. What does that imply?
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Sorry about that one thing.
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RonWeasley
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Re: Reverse puzzles and impossible positions
« Reply #28 on: May 26th, 2010, 3:27pm » |
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These are great!
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Hippo
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Re: Reverse puzzles and impossible positions
« Reply #29 on: May 26th, 2010, 10:20pm » |
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on May 26th, 2010, 2:34pm, 722caasi wrote:| Hippo: The last move could just have been a suicide. What does that imply? |
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OK, nice solution to both problems as they are stated. May be explaination of the winning strategy would help  .
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| « Last Edit: May 27th, 2010, 1:15am by Hippo » |
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