A possible solution with ALS:
From your grid, Locked Candidates (4 in b5), Hidden Triple (259 in b6) and Finned X-Wing (6 c28 r68 f[r7c2]) lead to:
- Code: Select all
.---------------------.---------------------.---------------------.
| 569 7 8 | 1359 3569 13469 | 1459 2 1459 |
| 259 24 2459 | 8 579 149 | 14579 3 6 |
| 1 3 4569 | 579 2 469 | 45789 478 45789 |
:---------------------+---------------------+---------------------:
| 4 128 12357 | 6 379 139 | 259 78 59 |
| 678 9 367 | 2 347 5 | 4678 1 478 |
| 2567 126 12567 | 179 479 8 | 259 467 3 |
:---------------------+---------------------+---------------------:
| 6789 468 4679 | 39 1 369 | 4678 5 2 |
| 3 12468 1249 | 59 5689 7 | 1468 468 148 |
| 678 5 167 | 4 68 2 | 3 9 178 |
'---------------------'---------------------'---------------------'
Here I have the same chain as
Steve K (just different notation and starting point):
Continuous Nice Loop [r1c4]=1=[r6c4]=7=[r3c4]-7-[r2c5]=7=[r2c7]=1=[r2c6]-1-[r1c4] => [r1c6]<>1, [r2c7]<>459, [r6c4]<>9
Then (equivalent to Steve's chain 2b):
Almost Locked Set XY-Chain: A=[r3c46789] - {456789}, B=[r7c46] - {369}, C=[r579c1] - {6789}, D=[r12c1],[r2c23] - {24569}, RCs=6,9, X=4,5,9 => [r3c3]<>4, [r3c3]<>5, [r3c3]<>9
Naked Single (6) and Locked Candidates (4 in b1) lead to:
Almost Locked Set XY-Wing: A=[r1c1479] - {13459}, B=[r2347c6] - {13469}, C=[r78c4],[r89c5] - {35689}, Y,Z=3,6, X=4,9 => [r1c6],[r3c789]<>4, [r1c6]<>9
Hidden Single (4), Naked Pair (78 in c8)
Skyscraper: 7 in [r4c8],[r6c4] (verbunden durch [r3c48]) => [r4c5]<>7
X-Chain: 6 [r8c8]=6=[r6c8]-6-[r5c7]=6=[r5c1]-6-[r9c1]=6=[r9c5] => [r8c5]<>6
Discontinuous Nice Loop [r3c4]=7=[r6c4]=1=[r1c4]-1-[r2c6]-9-[r3c4] => [r3c4]<>9
Locked Candidates Type 2 (Claiming): 9 in r3 => [r1c79]<>9
Discontinuous Nice Loop [r4c2]-1-[r4c6]=1=[r2c6]-1-[r2c7]-7-[r3c8]-8-[r4c8]=8=[r4c2] => [r4c2]<>1
W-Wing: 7 in [r6c4],[r9c3] verbunden durch 1 in [r4c36] => [r6c3]<>7
Sashimi Swordfish: 1 r249 c369 f[r2c7] => [r1c9]<>1
Locked Candidates Type 1 (Pointing): 1 in b3 => [r8c7]<>1
Discontinuous Nice Loop [r4c6]=1=[r4c3]-1-[r9c3]-7-[r9c9]=7=[r7c7]-7-[r2c7]-1-[r2c6]=1=[r4c6] => [r4c6]<>3, [r4c6]<>9
Singles
There are more steps in total, but some of them are rather easy.