The New Sudoku Players' Forum

by **daj95376** » Tue Oct 03, 2006 3:50 pm

Code: Select all: 4 . . . . . . . 9 . . . . 7 . . . . . . 3 4 . 2 8 . . . . 1 . . 9 6 . . . 8 . . 3 . . 7 . . . 2 5 . . 4 . . . . 5 6 . 1 3 . . . . . . 8 . . . . 9 . . . . . . . 2 # Arabian Star from Claudia # after SSTS *-----------------------------------------------------------------------------* | 4 -12567 *678 | 138 156 3568 |*1257 12356 9 | | 12568 1256 689 | 1389 7 3568 | 125 123456 13456 | | 1567 15679 3 | 4 1569 2 | 8 156 1567 | |-------------------------+-------------------------+-------------------------| | 357 3457 1 | 78 24 9 | 6 2358 358 | | 56 8 469 | 12 3 46 | 1259 7 15 | | 367 3679 2 | 5 16 #78 | 4 1389 138 | |-------------------------+-------------------------+-------------------------| | 278 247 5 | 6 29 1 | 3 489 478 | |-12367 -123467 *467 | 29 8 *3457 |*1579 1456 -14567 | | 9 -13467 *678 |+37 45 *3457 |*157 14568 2 | *-----------------------------------------------------------------------------*

I'm not up on my finned fish, but the asterisk (*) cells seem to form a Swordfish in <7> with a quasi-fin (#). However, since the quasi-fin is not in a box with another member of the Swordfish, it appears that nothing can be derived using the standard definition of a finned fish. But, the relationship [r6c6]-7-[r4c4]=7=[r9c4] exists. This causes [r9c2]<>7 and reduces the Swordfish to an X-Wing. The final result is the same eliminations as the original Swordfish -- excluding [r9c4]. I called it a quasi-finned Swordfish in another posting. Does it have another name ... or an equivalent technique?

In a finned fish relationship, (I believe) one looks for an overlap to derive common eliminations. In a quasi-finned fish relationship, eliminations are prevented.

by **Myth Jellies** » Tue Oct 03, 2006 5:55 pm

Nothing better than discovering this stuff on your own.

Here is a link with similar deductions and further links

http://forum.enjoysudoku.com/viewtopic.php?t=4731

(Havard, Mike Barker, and others added some stuff since the last time you posted to it, daj.)

by **Havard** » Tue Oct 03, 2006 6:21 pm

[EDIT: Said wrong stuff.]

by **ronk** » Tue Oct 03, 2006 7:38 pm

[edit: no longer a reason for the original post]

by **Havard** » Tue Oct 03, 2006 7:47 pm

oops, I'm sorry. Getting late. Thanks for pointing out my mistake!

by **daj95376** » Tue Oct 03, 2006 8:14 pm

Actually there are two overlapping, finned Jellyfish for <7> that're more appropriate for the eliminations I indicated.

Code: Select all: *-----------------------------------------------------------------------------* | 4 -12567 678 | 138 156 3568 | 1257 12356 9 | | 12568 1256 689 | 1389 7 3568 | 125 123456 13456 | |*1567 *15679 3 | 4 1569 2 | 8 156 *1567 | |-------------------------+-------------------------+-------------------------| |*357 *3457 1 |#78 24 9 | 6 2358 358 | | 56 8 469 | 12 3 46 | 1259 7 15 | |*367 *3679 2 | 5 16 #78 | 4 1389 138 | |-------------------------+-------------------------+-------------------------| |*278 *247 5 | 6 29 1 | 3 489 *478 | |-12367 -123467 467 | 29 8 3457 | 1579 1456 -14567 | | 9 -13467 678 | 37 45 3457 | 157 14568 2 | *-----------------------------------------------------------------------------* Jellyfish [r3467c1249] for <7>, Fin: [r6c6]=7 => Swordfish [r347c129] -or- Jellyfish [r3467c1269] for <7>, Fin: [r4c4]=7 => Swordfish [r367c129]

Another interpretation:

Code: Select all: Double Implication Chain for <7> in [b5] [r4c4]=7 => Swordfish [r367c129] [r6c6]=7 => Swordfish [r347c129]

Note: Claudia has produced multiple Arabian-Star puzzles as of this message. This is the first and shouldn't be confused with the KILLER Jellyfish version mentioned elsewhere.