Code: Select all
*-----------*
|.4.|5.1|.8.|
|..2|.6.|9..|
|...|9.7|...|
|---+---+---|
|.17|...|69.|
|28.|...|.51|
|.3.|...|.4.|
|---+---+---|
|...|789|...|
|...|...|...|
|..1|2.6|8..|
*-----------*
Code: Select all
*---------------------------------------------------------------------*
|B3679 4 B369 | 5 23 1 | 237 8 2367 |
| 1357 d57 2 | 348 6 348 | 9 -137 3457 |
|A13568 56 A3568 | 9 234 7 | 145 1236 23456 |
|-----------------------+----------------------+----------------------|
| 45 1 7 | 348 345 C23458 | 6 9 C238 |
| 2 8 49 | 6 79 34 | 37 5 1 |
|B569 3 B569 | 1 79 C258 | 27 4 C278 |
|-----------------------+----------------------+----------------------|
| 3456 256 3456 | 7 8 9 | 145 1236 23456 |
|A678 D2679 A68 | 34 1 345 | 45 d'267 D2679 |
| 3457 D579 1 | 2 45 6 | 8 d'37 D34579 |
*---------------------------------------------------------------------*
(4=3)r5c6 - (3=5&4)r4c15 xyz-wing to kill the 4's in r4c46.
In the meantime, there are a few advanced uniqueness rectangle tricks that you can take advantage of. Three of them have extra candidates in all four cells. Uppercase letters mark out the four rectangles.
A) 68-UR in r38c13. Two strong 8-links form a corner at r3c1, and the opposite corner contains just the base candidates, 68. Therefore r1c3 <> 6.
B) 69-UR in r16c13. Two strong 9-links form a corner at r1c1. There is also a strong 6-link that does not include that corner, therefore r1c1 <> 6.
C) 28-UR in r46c69. Two strong 2-links form a corner at r4c6. Two strong 8-links also form a corner at r6c9. For the same reason as in B, we know that r4c6 <> 8, and r6c9 <> 2.
D) 79-UR in r89c29. Here the 9's are locked into the UR, so if the deadly pattern is to be avoided, it will have to be the 7's that move out. If the move occurs out of r89c2, then the only other spot in c2 is r2c2. If the move occurs out of r89c9, then the only other spots in box 9 are r89c8. Since one or both of these alternate landing places has to contain a 7, any cell which sees both of them cannot contain a 7. Therefore r2c8 <> 7.
Just for grins and giggles...
If you'd like to express these uniqueness tricks as AICs, you need to note that A, B, and C use a special URCorner avoidance weak link that goes as follows: if you have two strong links forming a corner for one of your base candidates, then you have two URC weak links that exist between the other base candidate in that corner and each of the base candidates in the opposite corner. The URC weak link is represented by "-URC-", and I've emphasized the strong UR corner links with a "= (N&N)[cell1,cell2]" structure. Thus if you'd like to express these tricks as AIC's you could write something like the following....
A: (8)r3c1 = (8&8)[r3c3,r8c1] - (8=6)r8c3 -URC- (6=1358)r3c1 => r3c1 <> 6
B: (9)r1c1 = (9&9)[r1c3,r6c1] - (6)r6c1 = (6)r6c3 -URC- (6=379)r1c1 => r1c1 <> 6
C1: (2)r4c6 = (2&2-8&8)[r4c9,r6c6] = (8)r6c9 -URC- (8=2345)r4c6 => r4c6 <> 8
C2: (8)r6c9 = (8&8-2&2)[r4c9,r6c6] = (2)r4c6 -URC- (2=78)r6c9 => r6c9 <> 2
D: (7)r2c2 = (7&9)r89c2 -UR- (7&9)r89c9 = (7)r89c8 => r2c8 <> 7