## Using Simple Colors Problem

Advanced methods and approaches for solving Sudoku puzzles

### Using Simple Colors Problem

[code][code]I am new to these forums so I hope someone can help me a problem that has vexed me.

I am filtering on "6's" using colors. I made r2c7 Blue and r2c9 green. Then I colored r5c7 green and r5c8 Blue.

Column 7 now contained both a blue and green cell so I thought that I could exclude a "6" from r7c7. That didn't work and to my surprise, it turned the "6" in c7 was in r7c7. What mistake an I making????? Thanks.

[code]*--------------------------------------------------------------------*
| 3 25 1 | 9 25 6 | 8 4 7 |
| 2489 289 7 | 1348 1238 13 | 126 5 1369 |
| 2489 6 24589 | 13478 12358 57 | 12 239 139 |
|----------------------+----------------------+----------------------|
| 6 1237 234 | 5 9 8 | 17 3 134 |
| 5 89 489 | 13 7 13 | 46 689 2 |
| 1789 13789 389 | 6 4 2 | 157 389 1359 |
|----------------------+----------------------+----------------------|
| 178 3578 358 | 1378 13568 9 | 2456 26 456 |
| 278 4 2358 | 378 3568 57 | 9 1 56 |
| 19 159 6 | 2 15 4 | 3 7 8 |
*--------------------------------------------------------------------*[/code]
Gee

Posts: 50
Joined: 18 March 2007

### Re: Using Simple Colors Problem

Just to make things a bit clearer.
Gee wrote:I am new to these forums so I hope someone can help me a problem that has vexed me.

I am filtering on "6's" using colors. I made r2c7 Blue and r2c9 green. Then I colored r5c7 green and r5c8 Blue.

Column 7 now contained both a blue and green cell so I thought that I could exclude a "6" from r7c7. That didn't work and to my surprise, it turned the "6" in c7 was in r7c7. What mistake an I making????? Thanks.

Code: Select all
`*--------------------------------------------------------------------* | 3      25     1      | 9      25     6      | 8      4      7      | | 2489   289    7      | 1348   1238   13     | 126    5      1369   | | 2489   6      24589  | 13478  12358  57     | 12     239    139    | |----------------------+----------------------+----------------------| | 6      1237   234    | 5      9      8      | 17     3      134    | | 5      89     489    | 13     7      13     | 46     689    2      | | 1789   13789  389    | 6      4      2      | 157    389    1359   | |----------------------+----------------------+----------------------| | 178    3578   358    | 1378   13568  9      | 2456   26     456    | | 278    4      2358   | 378    3568   57     | 9      1      56     | | 19     159    6      | 2      15     4      | 3      7      8      | *--------------------------------------------------------------------*`
MCC

Posts: 1275
Joined: 08 June 2005

You can colour the 6s in row 2 as there are only 2 of them. However you can't continue this colouring as there are more than 2 6s in column 7 and in column 9. The 6s in row 5 should be different colours. If the ones in row 2 are blue and green, use red and yellow for the ones in row 5. You can only use the same colours if there are only 2 6s in one of the columns.
HTH
ab
ab

Posts: 451
Joined: 06 September 2005

As ab said, coloring just doesn't apply in your case. In fact, different and harder techniques are needed to advance this puzzle. The quickest solution I can find is:

Code: Select all
` *--------------------------------------------------------------------* | 3      25     1      | 9      25     6      | 8      4      7      | | 2489   289    7      | 1348   1238   13     | 126    5      1369-  | | 2489   6      24589  | 13478  12358  57     | 12     29A    139-   | |----------------------+----------------------+----------------------| | 6      127    24     | 5      9      8      | 17     3      14B    | | 5      89     489    | 13     7      13     | 46     689-   2      | | 1789   13789  389    | 6      4      2      | 157    89-    159B   | |----------------------+----------------------+----------------------| | 178    3578   358    | 1378   13568  9      | 2456   26A    456B   | | 278    4      2358   | 378    3568   57     | 9      1      56B    | | 19     159    6      | 2      15     4      | 3      7      8      | *--------------------------------------------------------------------*`

A={2,6,9} on r37c8, B={1,4,5,6,9} on r4678c9, x = 6, z = 9
The ALS xz-rule implies r23c9, r56c8<>9, solving the puzzle.
re'born

Posts: 551
Joined: 31 May 2007