"Restricted Uncommons"
Here's another "restoring the record after the crash" post.
This thread seems to be a good place for this restoration in that the
technique employed is not just a doubly-linked ALS. It is also
an example of a twist on the technique that I have not seen expressed
before or after this.
Of course, I do not have the original thread to reproduce, only my
notes. I do have an accurate copy of the PM at the point of discussion,
but not the givens. I did not record the original poster's handle, but
he was stuck at the position below.
The original thread was posted in November 2009 in the Sudoku Players'
Forum under the header "Tricky?" in the "Help With Particular Puzzles"
sub-forum. One of those "What now?" type posts.
On Nov 11, 2009
aran responded with doubly-linked ALS in which
one of the restricted common candidates was a weakly linked AIC. He called
it at one point a "generated" RCC and at another a "developed" RCC. This
was nothing new and is actually discussed earlier in this (
ronk's) thread.
Now to the point!
During the discussion aran pointed out that "developed" RCCs
do not have
to be the same value, only weakly linked (as all RCCs are anyway.)
He somehow came up with an example using the "Tricky" puzzle and half-
jokingly called it a "restricted uncommon."
- Code: Select all
*--------------------------------------------------------------------*
| 68-9 7 29 | 168 5 14 | 24 3 2469 |
| 3 89 4 | 2678 28 67 | 5 269 1 |
| 16 5 12 | 3 246 9 | 247 8 2467 |
|----------------------+----------------------+----------------------|
| *2458 348 7 | 68 1 35 | 9 2456 23468 |
| *59 1 #359 | 4 678 2 | 378 56 3678 |
| *2458 348 6 | 78 9 35 | 1 245 23478 |
|----------------------+----------------------+----------------------|
| *149 6 #139 | 5 234 8 | 234 7 2349 |
| 7 349 8 | 12 234 14 | 6 249 5 |
| *45 2 #35 | 9 67 67 | 348 1 348 |
*--------------------------------------------------------------------*
* Set A (124589)r45679c1
# Set B (1359)r579c3
1st RCC (1)r7c1 -(1)r7c3
2nd RCC (8)r46c1-(9)r57c3
Elim: r1c1<>9
The full AIC for the 2nd RCC :
(8)r46c1-r1c1=r2c2-(8=2)r2c5-(2=34)r78c5-(4)r8c6=r1c6-(4=2)r1c7-(2=9)r1c3-(9)r57c3
The elim is not significant, as it was just a demonstration of the possibilities.
If there are other examples of this usage I'd be keen to see them.