## How is this solved by colors?

Post the puzzle or solving technique that's causing you trouble and someone will help

### How is this solved by colors?

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         |                | *--------------------------------------------------*`

Posts: 23
Joined: 21 February 2006

### Re: How is this solved by colors?

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

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

Awesome...thats perfectly explained.

Thanks.