The New Sudoku Players' Forum

[Pat]

and while i have no idea what "vv" means

That is my short hand for vice versa

yes, that part i did figure out a few minutes too late--



so, is this the earliest finless-Franken Swordfish ?

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 X  /  /  |  X  /  X  |  /  /  /
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 *  .  .  |  X  /  /  |  .  .  .
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r37b5\c146

[ronk]

Here is an interesting observation for a Sashimi Swordfish with the fin in the same box as 2 lines from the covered set.

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 *  /  *  | .  #  .  | *  /  *
 .  X  .  | *  /  *  | .  X  .
 .  X  .  | *  /  *  | .  X  .
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 .  /  .  | .  /  .  | .  /  .
 .  X  .  | .  X  .  | .  X  .
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...
The 2 empty cells in r23c5 combined with the finned swordfish eliminations in r23c46 will trigger Locked Candidates in box2\row 1, causing the remaining eliminations in row 1.

I guess that's one step using the "hidden pattern" technique ... but two steps using sashimi swordfish.

But it does beg the question ... should the following be considered separate ccc\rrr exemplars?

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 *  X  * |  *  X  * |  *  X  *
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 swordfish ccc\rrr (1 row in each of 3 bands)

 .  /  . |  .  /  . |  .  /  .
 *  X  * |  *  X  * |  *  X  *
 *  X  * |  *  X  * |  *  X  *
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 swordfish ccc\rrr (2 rows in one band)

so, is this the earliest finless-Franken Swordfish ?

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 *  .  .  |  X  /  /  |  .  .  .
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r37b5\c146

I'm not aware of anything earlier ... but I'd be surprised if it actually was the earliest. In any case, the 'franken' name hadn't appeared yet. And when it did ... a ccc\rrb would have been a franken swordfish, but the rrb\ccc would not.

And had we known then what we know today, that swordfish would have had fewer 'empty cells.'

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

[Pat]

the franken name hadn't appeared yet

history:

Havard (2006.Mar.15) seems to be introducing the Frankenfish as a new idea
- is this perhaps where the Franken name first appeared?

he soon offers an example -

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



- at this point still considering it as having a fin;

in response, [ Ruud (2006.Mar.16) and ] Ruud (2006.Mar.16) may be introducing the finless-Franken - if i got it right - else i hope someone can straighten me out

thanks!
~ Pat

[Havard]

history:

Havard (2006.Mar.15) seems to be introducing the Frankenfish as a new idea
- is this perhaps where the Franken name first appeared?

yup!
http://forum.enjoysudoku.com/viewtopic.php?p=23422#p23422

at this point still considering it as having a fin;

Well, actually 8 fins! The original Frankenfish was a swordfish with a basis set of three columns, and a cover set of one row and two boxes, with then one additional fin (by todays standards). Interestingly that one "fin" was concidered a "head" in those days, and what you refer to as "finless-Franken" was actually coined "headless swordfish" in this post:
http://forum.enjoysudoku.com/viewtopic.php?p=23272#p23272 (2006.Mar.14) (I was reading the following posts, and it is quite funny to see how some things have changed since then! )

Havard

[ronk]

in response, [ Ruud (2006.Mar.16) and ] Ruud (2006.Mar.16) may be introducing the finless-Franken - if i got it right - else i hope someone can straighten me out

Ruud's fish were basic row-column fish ... so no franken fish there.

[daj95376]

Basic fish question.

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 *-----------*
 |...|...|8..|
 |9..|.4.|.6.|
 |.2.|.68|..5|
 |---+---+---|
 |.3.|...|...|
 |.4.|.5.|...|
 |..6|...|798|
 |---+---+---|
 |..1|3.6|..4|
 |...|4..|.5.|
 |2..|57.|6..|
 *-----------* # gurth GC06


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# at this point, Coloring could be used for these eliminations in <1>
 *-----------------------------------------------------------*
 | 4     6     5     | 1     2     3     | 8     7     9     |
 | 9     1     8     | 7     4     5     | 23    6     23    |
 | 3     2     7     | 9     6     8     | 4     1     5     |
 |-------------------+-------------------+-------------------|
 | 78    3     29    | 68   G19    179   | 5     4     26-1  |
 | 78    4     29    | 68    5     79-1  |B123   23    1236  |
 | 1     5     6     | 2     3     4     | 7     9     8     |
 |-------------------+-------------------+-------------------|
 | 5     7     1     | 3     89    6     | 29    28    4     |
 | 6     89    3     | 4    B189   2     |G19    5     7     |
 | 2     89    4     | 5     7     19    | 6     38    13    |
 *-----------------------------------------------------------*


Are there two Sashimi X-Wings in <1> (as well) that would produce the same eliminations?

Is it fair to assume that Coloring would normally be credited with these eliminations?

[Ruud]

It depends on the order in which the solving techniques are tested.

The same eliminations can be done with:

- 2 Sashimi X-Wings
- A Skyscraper
- 2 Turbot fish
- 2 Empty Rectangles
- Simple coloring

The Skyscraper seems the most elegant alternative. (personal flavor)

Ruud

[ArkieTech]

The 2 Sashimi X-Wings looks like a turbot with a force.

I can't see a solution or what is next. Help

[ronk]

The 2 Sashimi X-Wings looks like a turbot with a force.

I can't see a solution or what is next. Help

Please pursue the solution to gurth's GC06 here where it was introduced.

[Carcul]

I can't see a solution or what is next. Help

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 *-----------------------------------------------------*
 | 4     6     5  | 1     2     3   | 8     7     9    |
 | 9     1     8  | 7     4     5   | 23    6     23   |
 | 3     2     7  | 9     6     8   | 4     1     5    |
 |----------------+-----------------+------------------|
 | 78    3     29 | 68    19    179 | 5     4     126  |
 | 78    4     29 | 68    5     179 | 123   23    1236 |
 | 1     5     6  | 2     3     4   | 7     9     8    |
 |----------------+-----------------+------------------|
 | 5     7     1  | 3     89    6   | 29    28    4    |
 | 6     89    3  | 4     189   2   | 19    5     7    |
 | 2     89    4  | 5     7     19  | 6     38    13   |
 *-----------------------------------------------------*


[r8c2]=8=[r9c2]=9=[r9c6]=1=[r9c9]-1-[r8c7]-9-[r8c2], => r8c2<>9 solving the puzzle.

Carcul

[ArkieTech]

Carcul said:

[r8c2]=8=[r9c2]=9=[r9c6]=1=[r9c9]-1-[r8c7]-9-[r8c2], => r8c2<>9 solving the puzzle.

Thanks Carcul

dan

[Pat]

(finless) Franken Swordfish,
with overlap in "cover"

ccc\rrb :
"base" = Columns 6,7,8
"cover" = Rows 6,7 + Box 6 (note overlap)

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 ...  ../  //.
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 ...  ../  ..*
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the extra exclusions r6c78
are due to the overlap in the "cover"
as explained by Mike Barker —

In the case of Mutant fish,
it is also possible for a candidate to exist in a cell common to two units of the cover set.

This candidate can also be eliminated,
since placing a candidate in this cell will reduce the number of units available in the covering set by two,
leaving too few units in which to place digits.

yes — and also true for Frankenfish.

[ronk]

(finless) Franken Swordfish,
with overlap in "cover"

ccc\rrb :
"base" = Columns 6,7,8
"cover" = Rows 6,7 + Box 6 (note overlap)

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

the extra exclusions r6c78
are due to the overlap in the "cover"
as explained by Mike Barker —

[figure edited by ronk]

You are correct, but it is a degenerate pattern. The franken x-wing c78b69 would eliminate r456789c9. Then locked candidates in box 9 causes r7c6<>X, r6c6=X and r6c78<>X. That said, I will likely add it to the exemplars anyway.

[Pat]

The franken x-wing c78b69 would eliminate r456789c9.

box-to-line exclusions (box3 to c9),
no need X-wing for this part.

Then locked candidates in box 9 causes r7c6<>X, r6c6=X and r6c78<>X.

yes.
so the Franken Swordfish merely accomplishes in one step
what would otherwise take several steps--


funny i was just making exactly that point concerning the Franken X-wing rb\cc

~ Pat

[ronk]

The franken x-wing c78b69 would eliminate r456789c9.

box-to-line exclusions (box3 to c9),
no need X-wing for this part.

Duh! I've used that same argument before the "franken" term ever existed ... but only a little suprised to miss it this time around.