The New Sudoku Players' Forum

[MotsCroises]

Hi,

In order to explain some Sudoku with a XY-Chain with more than 3 candidates in some cells, I tried with another member of a Sudoku French forum to find a special case.

I found what looks like a XY-Chain, with a special case in the beginning (or in the end),

Then going deeper into the problem, I found a general explanation for this case.

You can look on my website (in French), for pictures ;-):
http://www.mots-croises.ch/Manuels/Sudoku/XY-Color.htm

Or here, in English Google translation.

You can also have a look at the diagram (example):


I begin with a XY-Chain: (XY-Wing with more than 3 cells).

And in the chain, I switch from XY-Chain to Coloring (even number of cells).

And at the end, I continue with XY-Chain for the last cells (one cell or more).

My question is: according to you, is this a new solution method ? If not, what is the method's name?

Thanks in advance

Henri

[Bob Hanson]

I've been calling this "3D Medusa" but I think it is also called "advanced coloring" See

http://www.stolaf.edu/people/hansonr/sudoku
http://www.stolaf.edu/people/hansonr/sudoku/explain.htm
http://www.stolaf.edu/people/hansonr/sudoku/top95-methods.htm

Nice diagram, by the way!

[tso]

Sudoku Susser calls this "Comprehensive forcing chains". Pencil and paper solvers might just call it "forcing chains".