Starting from
003000004000900078060005000005043010000010000020650800000500020690001000700000900
we reach
Code: Select all
+----------------+----------------+----------------+
| 2589 78 3 | 1 2678 2678 | 256 569 4 |
| 25 14e 14f | 9 236 26 | 2356 7 8 |
| 289 6 79 | 4 2378 5 | 123 39 129 |
+----------------+----------------+----------------+
| 89 78 5 | 27 4 3 | 267 1 2679 |
| 34a 34b 6 | 278 1 2789 | 257 59 2579 |
| 1 2 79 | 6 5 79 | 8 4 3 |
+----------------+----------------+----------------+
| 34c 134d 148g | 5 9 4678 | 1467 2 167 |
| 6 9 248 | 2378 278 1 | 3457 358 57 |
| 7 5 1248 | 238 268 2468 | 9 368 16 |
+----------------+----------------+----------------+
abcd is also an X-wing on <3>, so b = c = <3>.
There is another UR in defg.
Also, there is an Empty Rectangle (ER) which removes <9> in R3C9. (No matter where the <9> falls in R4, R3C9 is not <9>.) This ER breaks the puzzle wide open. Look at
http://www.sudoku.com/forums/viewtopic.php?t=3251
Best wishes,
Keith