unsolvable sudoku

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unsolvable sudoku

Postby bluemoose » Wed Dec 07, 2005 11:14 pm

At the following site are some Sudoku puzzles which are "unsolvable"

There is only 1 solution to each but you can not solve them with any known method other than guess-and-check

www.sudoku.org.uk/bifurcation.htm { broken link }
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Postby rubylips » Thu Dec 08, 2005 12:52 am

Clearly the puzzles haven't been set by a regular reader of this forum - all of them fall to forced chains, some of them to fishy cycles (i.e. forced chains tat feature just a single value). Number 7 is the most interesting.
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re: Michael Mepham's "unsolvable"

Postby Pat » Tue Dec 27, 2005 3:01 pm

Pat (2005.Oct.11) wrote:---also see www.sudoku.Org.UK/bifurcation.htm { broken link } The "unsolvable" sudoku:
Michael Mepham wrote:The puzzles below are guaranteed to have a unique solution, but defy known logical solving methods.

rubylips wrote:
bluemoose wrote:At the following site are some Sudoku puzzles which are "unsolvable" - you cannot solve them with any known method other than guess-and-check:
www.sudoku.org.uk/bifurcation.htm { broken link }

All of them fall to forced chains, some of them to fishy cycles (i.e. forced chains that feature just a single value).
Number 7 is the most interesting.


in www.SuDoku.Org.UK/cgi-bin/discus/discus.cgi?pg=topics { broken link } Michael Mepham's forum,
r.e.s. has already www.sudoku.org.uk/discus/messages/6/240.html?1128900375 { broken link } commented (2005.Oct.8) on the first 3 of those puzzles:
r.e.s. wrote:The online solver at act365.com/sudoku/index.htm is quite good with forcing chains, and it solved all 3 of the "unsolvable" sudokus that you recently posted at www.sudoku.Org.UK/bifurcation.htm
- so it's not (any longer) the case that these "defy known logical solving methods".

- Pat
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Re: re: Michael Mepham's "unsolvable"

Postby Chessmaster » Wed Feb 01, 2006 11:35 pm

Pat wrote:---


he changed it and will follow the rules that i mut be sloved with logic.
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