The New Sudoku Players' Forum

[tonyjer]

Hi Everyone

This puzzle was posted here a few weeks ago and tried to solve it without reference to the advice given.

Got as far as here and then ran it thru Andrew Stuart's solver which highlighted the hidden UR which eliminates 1 from F4 based on one strong link etc.

I thought I understood most of the UR types but cant see the logic here.

Can someone help me understand how 1 can be removed from the roof tile at F4?

Many thanks.

Tony

Code: Select all

765/?8?/?23
928/?53/67?
134/627/985
5??/?46/7?9
?4?/?7?/?56
6?7/??5/???
45?/7??/36?
??6/5??/?47
87?/?6?/59?


[re'born]

tonyjer,

Your PM grid should be something like:

Code: Select all

 *--------------------------------------------------------------------*
 | 7      6      5      | 149    8      149    | 14     2      3      |
 | 9      2      8      | 14     5      3      | 6      7      14     |
 | 1      3      4      | 6      2      7      | 9      8      5      |
 |----------------------+----------------------+----------------------|
 | 5      18     12     | 1238*  4      6      | 7      13*    9      |
 | 23     4      1239   | 1289   7      129    | 28     5      6      |
 | 6      189    7      | 12389* 139    5      | 248    13*    248    |
 |----------------------+----------------------+----------------------|
 | 4      5      129    | 7      19     1289   | 3      6      128    |
 | 23     19     6      | 5      139    1289   | 128    4      7      |
 | 8      7      123    | 1234   6      124    | 5      9      12     |
 *--------------------------------------------------------------------*


r6c4=1 => r6c8 = 3 => r4c8 = 1. Now the strong link on 3 in row 4 implies that r4c4 = 3. This gives a deadly pattern in r46c48[13]. Hence, r6c4<>1.

This is what Mike Barker called a UR+2B/1SL.

[tonyjer]

Repn'A

Thanks for the prompt reply.

Forgot how to post a grid with candidates. Can you refresh my memory?

Thanks

Tony

[underquark]

Easiest way is to enter the values into Simple Sudoku, click on the Copy button and paste it into a forum reply, keeping the bit you need (either original values, candidates or both):

*--------------------------------------------------------------------*
| 7 6 5 | 149 8 149 | 14 2 3 |
| 9 2 8 | 14 5 3 | 6 7 14 |
| 1 3 4 | 6 2 7 | 9 8 5 |
|----------------------+----------------------+----------------------|
| 5 18 12 | 1238 4 6 | 7 13 9 |
| 23 4 1239 | 1289 7 129 | 28 5 6 |
| 6 189 7 | 12389 139 5 | 248 13 248 |
|----------------------+----------------------+----------------------|
| 4 5 129 | 7 19 1289 | 3 6 128 |
| 23 19 6 | 5 139 1289 | 128 4 7 |
| 8 7 123 | 1234 6 124 | 5 9 12 |
*--------------------------------------------------------------------*

Then select all the text and click on the "Code" button to get it neat:

Code: Select all

 
 *--------------------------------------------------------------------*
 | 7      6      5      | 149    8      149    | 14     2      3      |
 | 9      2      8      | 14     5      3      | 6      7      14     |
 | 1      3      4      | 6      2      7      | 9      8      5      |
 |----------------------+----------------------+----------------------|
 | 5      18     12     | 1238   4      6      | 7      13     9      |
 | 23     4      1239   | 1289   7      129    | 28     5      6      |
 | 6      189    7      | 12389  139    5      | 248    13     248    |
 |----------------------+----------------------+----------------------|
 | 4      5      129    | 7      19     1289   | 3      6      128    |
 | 23     19     6      | 5      139    1289   | 128    4      7      |
 | 8      7      123    | 1234   6      124    | 5      9      12     |
 *--------------------------------------------------------------------*


[tonyjer]

Many thanks for your help

Thanks for your time.

Tony