The New Sudoku Players' Forum

[Jean-Christophe]

Should be easy from there

r5c7 = 6 -> r6c6 <> 7 = 6
r6c4 = 7, r8c6 = 7
r6c6 = 6 -> r7c7 <> 7
r9c7 = 7 -> r8c8 <> 6
r4c9 = 7 -> r6c8 <> 6
r1c8 = 6, r3c3 = 6
r14c8 = [64] -> r23c7 <> 5, r9c6 = 4 -> r8c7 <> 5
r6c7 = 5
r23c3 = [46] -> r12c2 <> 5, r8c1 = 4 -> r9c2 <> 5
r8c2 = 5, r9c9 = 5
r8c9 = 6
r9c7 = 7 -> r8c78 = [89], r6c8 = [89], r3c7 = 9
r3c9 = 4, r7c79 = [43]
...

Solution:
+-------+-------+-------+
| 9 7 8 | 4 5 3 | 2 6 1 |
| 5 1 4 | 2 6 9 | 3 7 8 |
| 3 2 6 | 1 7 8 | 9 5 4 |
+-------+-------+-------+
| 6 3 5 | 9 8 2 | 1 4 7 |
| 7 8 9 | 5 4 1 | 6 3 2 |
| 1 4 2 | 7 3 6 | 5 8 9 |
+-------+-------+-------+
| 2 6 7 | 8 9 5 | 4 1 3 |
| 4 5 1 | 3 2 7 | 8 9 6 |
| 8 9 3 | 6 1 4 | 7 2 5 |
+-------+-------+-------+

[HATMAN]

Thanks - blindness on my part

note I used a swordfish and turbot fish to get to that stage

[Jean-Christophe]

The sword on 3 is not needed, but this turbot fish (skyscraper) will unlock the grid
(4): r8c1=r8c9-r6c9=r6c2 -> r4c1, r7c2 <> 4
Sure there are other ways to unlock the grid.