4/26/07 Daily Nightmare
Posted: Thu Apr 26, 2007 12:23 am
After some singles, one gets to
The 6 cells in r4c569, r5c356 contain the candidates (1,2,3,4,5,7) with max multiplicity (1,1,2,1,1,1). Therefore, subset counting (or the ALS xz-rule) tells you that you can remove 3 from r4c2 and r5c7, solving the puzzle.
Alternatively, consider the broken wing pattern on 1
with guardians in r6c4 and r9c26. r6c2=1 knocks out the guardians in r6c4 and r9c2. Moreover, r6c2=1 => r9c1=1, killing the guardian in r9c6. Therefore, r6c2<>1, and after the applying the uncovered naked quad in row 6, the puzzle is solved.
Code: Select all
.---------------.---------------.---------------.
| 4 8 13 | 16 7 5 | 369 2 369 |
| 9 26 7 | 246 346 2468| 1 358 3568|
| 13 26 5 | 9 136 1268| 368 7 4 |
:---------------+---------------+---------------:
| 8 37- 6 | 25* 9 27* | 4 1 35* |
| 5 1379 134*| 8 14* 147*| 379- 6 2 |
| 2 179 14 | 1456 1456 3 | 5789 589 589 |
:---------------+---------------+---------------:
| 7 4 8 | 3 156 169 | 2 59 1569|
| 6 135 9 | 7 2 14 | 358 3458 1358|
| 13 135 2 | 1456 8 1469| 3569 3459 7 |
'---------------'---------------'---------------'
Alternatively, consider the broken wing pattern on 1
Code: Select all
*-----------------------------------------------------------*
| 4 8 13* | 16* 7 5 | 369 2 369 |
| 9 26 7 | 246 346 2468 | 1 358 3568 |
| 13* 26 5 | 9 136 1268 | 368 7 4 |
|-------------------+-------------------+-------------------|
| 38 37 6 | 25 9 27 | 4 1 358 |
| 5 1379 134 | 8 14 147 | 379 6 2 |
| 2 179- 14 | 1456& 1456 3 | 5789 589 589 |
|-------------------+-------------------+-------------------|
| 7 4 8 | 3 156 169 | 2 59 1569 |
| 6 135 9 | 7 2 14 | 358 3458 1358 |
| 13* 135& 2 | 1456* 8 1469& | 3569 3459 7 |
*-----------------------------------------------------------*