+-----------------------+----------------------+-----------------------+
| 3 2689 269 | 2679 5 1 | 4789 269 4679 |
| 679 4 2569 | 2679 6789 689 | 579 3 1 |
| 6789 1 2569 | 2679 4 3 | 5789 2569 5679 |
+-----------------------+----------------------+-----------------------+
| 89 7 1 | 4 3 2 | 6 589 59 |
| 5 e689 3 | f679 f6789 f689 | 1 4 2 |
| 4689 2689 2469 | 1 8-69 5 | 37 89 37 |
+-----------------------+----------------------+-----------------------+
| 2 d369 7 | 8 a69 4 | 359 1 3569 |
| c469 5 c469 | 3 1 b69 | 2 7 8 |
| 1 d369 8 | 5 2 7 | 349 69 3469 |
+-----------------------+----------------------+-----------------------+
3 2689 269 2679 5 1 4789 269 4679
679 4 2569 2679 6789 689 579 3 1
6789 1 2569 2679 4 3 5789 2569 5679
89 7 1 4 3 2 6 589 59
5 689 3 679 6789 689 1 4 2
4689 2689 2469 1 689 5 37 89 37
2 369 7 8 69 4 359 1 3569
469 5 469 3 1 69 2 7 8
1 369 8 5 2 7 349 69 3469
9r7c2579 => r5c2 <> 6,9
r7c2=9 - r7c5{n9 n6} - b5n6{r56c5 r5c46} - r5c2{n69 n8}
r7c5=9 - r8c6{n9 n6} - b7n6{r8c13 r79c2} - b4n6{r56c2 r6c13} - r6c5{n69 n8} - r5n8{c56 c2}
r5c79=9 - r9n9{c789 c2} - r7c5{n9 n6} - b5n6{r56c5 r5c46} - r5c2{n69 n8}
ste.
+---------------------+-----------------+---------------------+
| 36789 23689 2369 | 2679 5 1 | 4789 24689 4679 |
| 6789 4 2569 | 2679 6789 689 | 5789 3 1 |
| 6789 1 2569 | 2679 4 3 | 5789 25689 5679 |
+---------------------+-----------------+---------------------+
| 89 7 1 | 4 3 2 | 6 589 59 |
| 5 3689 3469 | 679 6789 689 | 1 489 2 |
| 34689 23689 23469 | 1 6789 5 | 34789 489 3479 |
+---------------------+-----------------+---------------------+
| 2 3569 7 | 8 69 469 | 3459 1 34569 |
| 469 569 4569 | 3 1 469 | 2 7 8 |
| 1 369 8 | 5 2 7 | 349 469 3469 |
+---------------------+-----------------+---------------------+
3 2689 269 | 2679 5 1 | 4789 269 4679
679 4 2569 | 2679 6789 689 | 579 3 1
6789 1 2569 | 2679 4 3 | 5789 2569 5679
------------------------+----------------------+---------------------
89 7 1 | 4 3 2 | 6 589 59
5 689 3 | 679 6789 689 | 1 4 2
4689 2689 2469 | 1 689 5 | 37 89 37
------------------------+----------------------+---------------------
2 369 7 | 8 69 4 | 359 1 3569
469 5 469 | 3 1 69 | 2 7 8
1 369 8 | 5 2 7 | 349 69 3469
pjb wrote:My take on the pattern overlay method:
---
No pattern of 6 includes r5c2 or r6c5 so 6 can be deleted from r5c2 and r6c5 =>
Naked pairs of 89 at r6c58 => -8 r6c12, -9 r6c123
Then
All patterns of 9 include r4c1 so this can be made equal to 9; stte
Phil
3s at r5c23 only ones in row/column => -3 r6c123.
4s at r9c79 only ones in row/column => -4 r7c79.
Naked triplets of 589 at r4c89, r6c8 => -8 r6c7, -9 r6c79
5s at r8c23 only ones in row/column => -5 r7c2.
Naked pairs of 37 at r6c79 => -7 r6c5
8s at r123c7 only ones in row/column => -8 r13c8.
8s at r2c56 only ones in box => -8 r2c17.
No pattern of 6 includes r5c2, r6c5 so 6 can be deleted from r5c2, r6c5
Naked pairs of 89 at r6c58 => -8 r6c12, -9 r6c123
All patterns of 9 include r4c1 so this can be made equal to 9
Resolution state after Singles and whips[1]:
+-------------------+-------------------+-------------------+
! 3 2689 269 ! 2679 5 1 ! 4789 2689 4679 !
! 679 4 2569 ! 2679 6789 689 ! 579 3 1 !
! 6789 1 2569 ! 2679 4 3 ! 5789 25689 5679 !
+-------------------+-------------------+-------------------+
! 89 7 1 ! 4 3 2 ! 6 589 59 !
! 5 689 3 ! 679 6789 689 ! 1 4 2 !
! 4689 2689 2469 ! 1 689 5 ! 3789 89 379 !
+-------------------+-------------------+-------------------+
! 2 369 7 ! 8 69 4 ! 359 1 3569 !
! 469 5 469 ! 3 1 69 ! 2 7 8 !
! 1 369 8 ! 5 2 7 ! 349 69 3469 !
+-------------------+-------------------+-------------------+
145 candidates.