The New Sudoku Players' Forum

[ronk]

Mike Barker, when you're bored to tears with nothing to do would you consider editing your "almost squirmbag" post to number the puzzles?

And thanks for posting them, Ron

[ronk]

Here ... if a fish with a big fin appears to be missing a row (column), a so called skinny fish, other reductions are possible. The dashes indicate cells without the candidate (in this case because of Box/Box eliminations):

Code: Select all

 . . . | * X * | X X -    . . . | * X X | X X *    . . . | . . . | X X *
 . . . | * X * | X X -    . . . | * X X | X X *    * X * | * X * | * * *
 . . . | * X * | X X -    . . . | * X X | X X *    . | . | . | . | X X *
-------+---|---+-|-|---  -------+---|-|-+-|-|---  ---|---+---|---+-|-|---
 . . . | . | . | | | -    . . . | . | | | | | .    . | . | . | . | | | .
 * * * | * * * | X X -    * * * | * X X | X X *    * X * | * X * | X X *
 . . . | . | . | | | -    . . . | . | | | | | .    . | . | . | . | | | .
-------+---|---+-|-|---  -------+---|-|-+-|-|---  ---|---+---|---+-|-|---
 . . . | . | . | | | .    . . . | . | | | | | .    . | . | . | . | | | .
 . . . | . | . | | | .    . . . | . | | | | | .    . | . | . | . | | | .
 . . . | . | . | | | .    * * * | * X X | X X *    * X * | * X * | X X *

Illustrating degenerate cases always seems to be problematic. To be consistent with the other two diagrams, however, I recommend replacing the first with ...

Code: Select all

 . . . | * X * | X X *
 . . . | * X * | X X *
 . . . | * X * | X X *
-------+---|---+-|-|---
 . . . | . | . | | | .
 * * * | * X * | X X *
 . . . | . | . | | | .
-------+---|---+-|-|---
 . . . | . | . | | | .
 . . . | . | . | | | .
 . . . | . | . | | | .

... along with the caveat, since the pattern is degenerate, those same exclusions (and a couple more) may be made with box/box exclusions in stack 3, followed by locked candidate exclusions in box 6 and then box 2.

[Myth Jellies]

Even though I posted this elsewhere, I thought it might be worthwhile to add it to this tank...

Michael Mephem's 4th extreme puzzle has an interesting biggish fish...

Code: Select all

 *-----------*
 |..5|3..|6..|
 |.2.|.7.|.4.|
 |...|.1.|..8|
 |---+---+---|
 |3..|4..|..1|
 |.6.|251|.8.|
 |2..|..8|..4|
 |---+---+---|
 |4..|.2.|...|
 |.7.|.4.|.9.|
 |..1|..3|4..|
 *-----------*

Basic methods will take you here...

Code: Select all

 *-----------------------------------------------------------------------------*
 | 179     489     5       | 3       89      24      | 6       127     279     |
 | 1689    2       3       | 5689    7       569     | 159     4       59      |
 | 679     49      679     | 569     1       24      | 2579    3       8       |
 |-------------------------+-------------------------+-------------------------|
 | 3       5       8       | 4       69      679     | 279     267     1       |
 | 79      6       4       | 2       5       1       | 379     8       379     |
 | 2       1       79      | 679     3       8       | 579     567     4       |
 |-------------------------+-------------------------+-------------------------|
 | 4       3       69      | 156789  2       5679    | 1578    157     567     |
 | 568     7       2       | 1568    4       56      | 1358    9       356     |
 | 569     89      1       | 5679    689     3       | 4       257     2567    |
 *-----------------------------------------------------------------------------*


Filtering on the sevens we have a swordfish with two distinct fins...

Code: Select all

 +-----------+-----------+-----------+
 |*7   .   . | .   .   . | .  *7  *7 |
 | .   .   . | .   7   . | .   .   . |
 | 7   .   7 | .   .   . | 7   .   . |
 +-----------+-----------+-----------+
 | .   .   . | .   .  A7 | 7  -7   . |
 |*7   .   . | .   .   . |#7  *.  *7 |
 | .   .   7 |a7   .   . | 7   7   . |
 +-----------+-----------+-----------+
 | .   .   . | 7   .  a7 | 7   7   7 |
 | .   7   . | .   .   . | .   .   . |
 |*.   .   . |#7   .   . | .  *7  *7 |
 +-----------+-----------+-----------+


Either the r159c189 swordfish is true, or the fin in r5c7 is true, or the fin in r9c4 is true, which with a little weak then strong link extension would imply A (r4c6) contains a 7. In all three possible cases, seven can be removed from r4c8.

I thought this was an interesting case of an almost finned swordfish.