Code: Select all
. 1 .|6 . .|9 . .
6 . .|3 7 .|. 4 .
. . .|. . 1|. . 6
-----+-----+-----
1 8 .|. . 2|7 . .
. 4 .|. . .|. 6 .
. . 5|7 . .|. 8 4
-----+-----+-----
3 . .|8 . .|. . .
. 2 .|. 3 9|. . 8
. . 4|. . 7|. 9 .
Code: Select all
.------------------.------------------.------------------.
| 2457 1 2378 | 6 2458 458 | 9 2357 2357 |
| 6 59 289 | 3 7 58 | 1258 4 125 |
| 2457 357 2378 | 2459 24589 1 | 2358 2357 6 |
:------------------+------------------+------------------:
| 1 8 36 | 459 4569 2 | 7 35 359 |
| 279 4 27 | 159 1589 358 | 1235 6 12359|
| 29 36 5 | 7 19 36 | 12 8 4 |
:------------------+------------------+------------------:
| 3 5679 1679 | 8 2456 456 | 2456 1257 257 |
| 57 2 167 | 45 3 9 | 456 157 8 |
| 8 56 4 | 125 1256 7 | 2356 9 235 |
'------------------'------------------'------------------'
A skyscraper for digit 7, represented by this AIC:
- (7): r1c9 = r7c9 - r7c2 = r3c2 => r1c13, r3c8 <> 7
- (6=579)r79c2|r8c1 - (9=56)r29c2 => r6c2, r78c3 <> 6
The first such pattern consists of ALS's r4c3489 (four cells, digits 34569) and r8c1348 (four cells, digits 14567). Digits 4 and 6 are restricted common digits -- in the two sets, digit 4 appears only in column 4, and digit 6 appears only in column 3.
The second such pattern is actually a classic Sue de Coq position as well -- viewed this way, box 5 and column 4 are the box and line, set A (in the box) is r6c5, with digits "19"; set B (in the line) is r8c4, with digits "45", and set C (in the line/box intersection) is r45c4, with digits "1459".
Once again, these don't add anything beyond the results of the second chain above. After basic followup of the eliminations from the first and second chains, the grid appears as follows:
Code: Select all
.---------------.----------------.---------------.
| 25 1 8 | 6 25 4 | 9 37 37 |
| 6 59 29 | 3 7 8 | 125 4 125 |
| 4 7 3 | *29 259 1 | 8 #25 6 |
:---------------+----------------+---------------:
| 1 8 6 | 59 4 2 | 7 35 359 |
| 279 4 27 | 159 8 3 | 125 6 1259|
| 29 3 5 | 7 19 6 | 12 8 4 |
:---------------+----------------+---------------:
| 3 69 179 | 8 6-2 5 | 4 *127 27 |
| 57 2 17 | 4 3 9 | 6 157 8 |
| 8 56 4 | #12 126 7 | 3 9 5-2 |
'---------------'----------------'---------------'
- (2): r7c8 = r3c8 - r3c4 = r9c4 => r7c5, r9c9 <> 2