How is this solved by colors?

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How is this solved by colors?

Postby bradles » Thu Feb 23, 2006 12:06 pm

Simple Sudoku suggests *7* can be excluded based on colors. I've used "a" and "b" as the representation of different colors. However, looking at the problem, I thought with colors, that you couldn't make a decision on which one was true or false until you had two of the same color in one box? Can someone explain how this one works?

Code: Select all
 *--------------------------------------------------*
 |                |                |           7    |
 |      7a        |           7b   |                |
 |           7b   | 7a             |                |
 |----------------+----------------+----------------|
 |       7b       |  *7*       7   |                |
 |            7a  |   7        7   |                |
 |                |                | 7              |
 |----------------+----------------+----------------|
 |                |                |      7         |
 | 7              |                |                |
 |                |      7         |                |
 *--------------------------------------------------*
bradles
 
Posts: 23
Joined: 21 February 2006

Re: How is this solved by colors?

Postby vidarino » Thu Feb 23, 2006 12:20 pm

We know that 'a' or 'b' must be true, and the cell in question can "see" a candidate of each color, and therefore can not contain a 7.
vidarino
 
Posts: 295
Joined: 02 January 2006

Postby TKiel » Thu Feb 23, 2006 12:22 pm

The cell marked with the * shares a row with a b cell and a column with an a cell, one of which must be true. It doesn't matter which is true or which is false, but one of them must be.

Tracy
TKiel
 
Posts: 209
Joined: 05 January 2006

Postby bradles » Thu Feb 23, 2006 12:42 pm

Awesome...thats perfectly explained.

Thanks.
bradles
 
Posts: 23
Joined: 21 February 2006


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