# The Grey Labyrinth is a collection of puzzles, riddles, mind games, paradoxes and other intellectually challenging diversions. Related topics: puzzle games, logic puzzles, lateral thinking puzzles, philosophy, mind benders, brain teasers, word problems, conundrums, 3d puzzles, spatial reasoning, intelligence tests, mathematical diversions, paradoxes, physics problems, reasoning, math, science.

Author Message
mathgrant
A very tilted cell member

Posted: Tue Jul 14, 2009 10:14 pm    Post subject: 1

According to the site where I found it, this chess puzzle was created by a Martin van Essen, and published in 2005. I thought that some people on here might enjoy seeing it.

White undoes one move, and then selfmates in 1 (i.e., forces Black to checkmate White on the next move)

Edit: By "undoes one move", I mean that the board shows a position after White has completed a move (i.e., it is Black's turn), and White restores the board to the position that it was before he moved and then makes another move instead.
_________________
My logic puzzle blog

Last edited by mathgrant on Wed Jul 15, 2009 1:46 am; edited 1 time in total
L'lanmal
Daedalian Member

 Posted: Wed Jul 15, 2009 1:44 am    Post subject: 2 I could wish for more clarity on what "Undoes a move" means. His own move? His opponent's? Any move all game? Half of an en-passant? Can undoing the move lead to an "illegal" position to move from? And whose move is it? I assume it means the board shows a position immediately after white's move - show another possible move white could have made that would force black to mate him. Anyways: Undo f5xg6 (En-passent), then g2-g4. Only legal move for black is h4xg3 (en-passent)++
mathgrant
A very tilted cell member

Posted: Wed Jul 15, 2009 1:49 am    Post subject: 3

 L'lanmal wrote: I could wish for more clarity on what "Undoes a move" means. His own move? His opponent's? Any move all game? Half of an en-passant? Can undoing the move lead to an "illegal" position to move from? And whose move is it? I assume it means the board shows a position immediately after white's move - show another possible move white could have made that would force black to mate him.

I edited the first post to be clearer on that; you're right, though.

 Quote: Anyways: Undo f5xg6 (En-passent), then g2-g4. Only legal move for black is h4xg3 (en-passent)++

Correct! I don't think I've ever seen such simultaneously absurd, awesome, and beautiful use of en passant before; I had to share this problem because of that.
_________________
My logic puzzle blog
MNOWAX
0.999... of a Troll

 Posted: Wed Jul 15, 2009 3:01 am    Post subject: 4 that is the coolest chess puzzle that I have seen in a long time [/geek] Nice find mathgrant!_________________The Man The Myth The Legend MNOWAX
Courk
Daedalian Member

 Posted: Wed Jul 15, 2009 8:32 am    Post subject: 5 I understand why black would make that move, what with winning being the point, but why is it the only legal move?
Scurra
Daedalian Member

 Posted: Wed Jul 15, 2009 9:40 am    Post subject: 6 It's taken me ages to work out why in my head. (That's why I gave up playing Chess!) Remember that White has taken a move back. So there is now a White pawn on F5 but, critically, a black pawn on G5 as well - i.e. the Black King is hemmed in more than it appears from the diagram. This leaves Black with three possible moves - Kxf5, g5-g4 or f3xg2. But one move allows White to block all of them, and simultaneously leaves Black with only one legal move - which is the checkmate. (Whereas just moving g2-g3 lets Black simply capture the white Pawn on f5 since it is undefended.) At least I think that's how it works. I am generally rubbish at this sort of thing._________________ still Quiz Olympiad champion. Must get a life. New definitions: COFFEE - someone who is coughed upon
L'lanmal
Daedalian Member

 Posted: Wed Jul 15, 2009 11:00 am    Post subject: 7 Yeah, it's the only legal move due to the absense of any other legal moves. There is nothing forcing that particular move (no check involved), just that all the black pawns are blockaded, and the king has no square it can move to. This is the reason that it does not work for the white pawn to have come from h5, because then the black f-pawn could still advance, and black could avoid mating white.
mathgrant
A very tilted cell member

Posted: Wed Jul 15, 2009 12:47 pm    Post subject: 8

 L'lanmal wrote: Yeah, it's the only legal move due to the absense of any other legal moves. There is nothing forcing that particular move (no check involved), just that all the black pawns are blockaded, and the king has no square it can move to. This is the reason that it does not work for the white pawn to have come from h5, because then the black f-pawn could still advance, and black could avoid mating white.

This is also the reason why the capture that White undoes has to be en passant.
_________________
My logic puzzle blog
Courk
Daedalian Member

 Posted: Wed Jul 15, 2009 9:17 pm    Post subject: 9 Oh, duh, I forgot en passant means capturing a pawn, too.
 Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year by All usersCourkL'lanmalmathgrantMNOWAXScurra Oldest FirstNewest First
 All times are GMT Page 1 of 1

 Jump to: Select a forum Puzzles and Games----------------Grey Labyrinth PuzzlesVisitor Submitted PuzzlesVisitor GamesMafia Games Miscellaneous----------------Off-TopicVisitor Submitted NewsScience, Art, and CulturePoll Tournaments Administration----------------Grey Labyrinth NewsFeature Requests / Site Problems
You cannot post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum