Sudoku Players' Forum (clone)

hi there.

in all the places i've looked, i didn't see an x-wing example where the candidate pairs are on the same block. still looks like an x-wing to me though.

is this still an xwing, or something else?

thank you!

Yes it is an x-wing but locked singles comes first and clears all eliminations.
If locked in columns then boxes 7,9 will be cleared.
4 in box 8 will be locked in to row 7 and clears box 8, while x-wing clears everything in a single step.

creint wrote:Yes it is an x-wing but locked singles comes first and clears all eliminations.
If locked in columns then boxes 7,9 will be cleared.
4 in box 8 will be locked in to row 7 and clears box 8, while x-wing clears everything in a single step.

thank you!!!

to add pictures to what client says:

the Box Line Reduction {1 fish/cyclopse} in box 7 is usually performed first

removing R7C123789

Code: Select all

.---------------------------------.---------------------------------.---------------------------------.
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
:---------------------------------+---------------------------------+---------------------------------:
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
:---------------------------------+---------------------------------+---------------------------------:
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
| 123456789  123456789  123456789 | 23456789   23456789   23456789  | 123456789  123456789  123456789 |
| 123456789  123456789  123456789 | 23456789   23456789   23456789  | 123456789  123456789  123456789 |
'---------------------------------'---------------------------------'---------------------------------'

if R7C123789 are removed
then again the box line reduction in box 7
removes R89C456 for eliminations

Code: Select all

.---------------------------------.---------------------------------.---------------------------------.
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
:---------------------------------+---------------------------------+---------------------------------:
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
:---------------------------------+---------------------------------+---------------------------------:
| 23456789   23456789   23456789  | 123456789  123456789  123456789 | 23456789   23456789   23456789  |
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
| 123456789  123456789  123456789 | 123456789  123456789  123456789 | 123456789  123456789  123456789 |
'---------------------------------'---------------------------------'---------------------------------'

thus the
Finned Franken X-wing of R89C123789 is Never really seen do to hierarchy

it is valid,
this form has many interesting shapes that still work for its base construction with 12 x's it can reduce to 2 per Row and its not nessisary for all x's to be lined on 2 column as its box/row or box/col constraints. compared to Row/Col or Col/Row of a normal x-wing.

Code: Select all

+---------------+------------+---------------+
| .    .    .   | .   .   .  | .    .    .   |
| .    .    .   | .   .   .  | .    .    .   |
| .    .    .   | .   .   .  | .    .    .   |
+---------------+------------+---------------+
| .    .    .   | .   .   .  | .    .    .   |
| .    .    .   | .   .   .  | .    .    .   |
| .    .    .   | .   .   .  | .    .    .   |
+---------------+------------+---------------+
| .    .    .   | 1   1   1  | .    .    .   |
| (1)  (1)  (1) | -1  -1  -1 | (1)  (1)  (1) |
| (1)  (1)  (1) | -1  -1  -1 | (1)  (1)  (1) |
+---------------+------------+---------------+

StrmCkr wrote:it is valid,
this form has many interesting shapes that still work for its base construction with 12 x's it can reduce to 2 per Row and its not nessisary for all x's to be lined on 2 column as its box/row or box/col constraints. compared to Row/Col or Col/Row of a normal x-wing.

yes indeed! thank you for your informative observations.