The New Sudoku Players' Forum

[Gee]

I had studied Rudd's examples of ALS and was doing pretty well until this came along. I have racked my brain (it's rather small) but I can't figure where I went wrong.

ALS A is r4c1, r4c3 ALS B is r4c7, r7c7, r7c9

(5) is restricted common for A & B
(3) is Common for A & B

It looks to me like I should be able to exclude the (3) in r7c1 since it can "see" the (3's) in both A & B

Your help will definitely be appreciated.


*-----------*
|7..|...|..5|
|..8|...|2..|
|.5.|9.4|38.|
|---+---+---|
|.8.|296|.7.|
|...|.5.|...|
|.6.|718|.3.|
|---+---+---|
|.42|8.9|.5.|
|..5|...|6..|
|1..|...|..8|
*-----------*


*-----------*
|7..|.8.|..5|
|4.8|...|2..|
|.5.|9.4|38.|
|---+---+---|
|.8.|296|.74|
|...|453|8..|
|.64|718|.3.|
|---+---+---|
|.42|8.9|.5.|
|8.5|...|6..|
|1..|...|..8|
*-----------*


*--------------------------------------------------------------------*
| 7 1239 1369 | 136 8 12 | 149 1469 5 |
| 4 139 8 | 1356 367 157 | 2 169 1679 |
| 26 5 16 | 9 267 4 | 3 8 167 |
|----------------------+----------------------+----------------------|
| 35 8 13 | 2 9 6 | 15 7 4 |
| 29 1279 179 | 4 5 3 | 8 1269 1269 |
| 259 6 4 | 7 1 8 | 59 3 29 |
|----------------------+----------------------+----------------------|
| 36 4 2 | 8 367 9 | 17 5 137 |
| 8 379 5 | 13 2347 127 | 6 1249 12379 |
| 1 379 3679 | 356 23467 257 | 479 249 8 |
*--------------------------------------------------------------------*

[ronk]

ALS A is r4c1, r4c3 ALS B is r4c7, r7c7, r7c9

(5) is restricted common for A & B
(3) is Common for A & B

It looks to me like I should be able to exclude the (3) in r7c1 since it can "see" the (3's) in both A & B

Two problems: 1) all the cells of set B do no share one unit (row, col, or box); and 2) even if (1) weren't a problem, r7c1 does not "see" all the 3s in ALS A.

[Gee]

Thank you Ronk for your reply. it's back to the drawing board for me but your clarification of my errors in logic is very helpful to me. Thanks again.