The Ultimate FISH Guide

Advanced methods and approaches for solving Sudoku puzzles

re: Franken

Postby Pat » Thu Nov 30, 2006 5:15 pm

tarek wrote:
Pat wrote: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 ?
rkral (2005.Nov.3) wrote:
Code: Select all
 *  .  .  |  *  .  *  |  .  .  .
 *  .  .  |  *  .  *  |  .  .  .
 X  /  /  |  X  /  X  |  /  /  /
 ---------+-----------+---------
 *  .  .  |  /  /  X  |  .  .  .
 *  .  .  |  X  /  /  |  .  .  .
 *  .  .  |  /  /  /  |  .  .  .
 ---------+-----------+---------
 X  /  /  |  X  /  X  |  /  /  /
 *  .  .  |  *  .  *  |  .  .  .
 *  .  .  |  *  .  *  |  .  .  .


r37b5\c146
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Postby ronk » Thu Nov 30, 2006 8:03 pm

Ruud wrote:Here is an interesting observation for a Sashimi Swordfish with the fin in the same box as 2 lines from the covered set.
Code: Select all
 *  /  *  | .  #  .  | *  /  *
 .  X  .  | *  /  *  | .  X  .
 .  X  .  | *  /  *  | .  X  .
----------+----------+---------
 .  /  .  | .  /  .  | .  /  .
 .  X  .  | .  X  .  | .  X  .
 .  /  .  | .  /  .  | .  /  .
----------+----------+---------
 .  /  .  | .  /  .  | .  /  .
 .  /  .  | .  /  .  | .  /  .
 .  /  .  | .  /  .  | .  /  .

...
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?:?:
Code: Select all
 .  /  . |  .  /  . |  .  /  .
 *  X  * |  *  X  * |  *  X  *
 .  /  . |  .  /  . |  .  /  .
---------+----------+----------
 .  /  . |  .  /  . |  .  /  .
 *  X  * |  *  X  * |  *  X  *
 .  /  . |  .  /  . |  .  /  .
---------+----------+----------
 .  /  . |  .  /  . |  .  /  .
 *  X  * |  *  X  * |  *  X  *
 .  /  . |  .  /  . |  .  /  .
 swordfish ccc\rrr (1 row in each of 3 bands)

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

Pat wrote:so, is this the earliest finless-Franken Swordfish ?
rkral (2005.Nov.3) wrote:
Code: Select all
 *  .  .  |  *  .  *  |  .  .  .
 *  .  .  |  *  .  *  |  .  .  .
 X  /  /  |  X  /  X  |  /  /  /
 ---------+-----------+---------
 *  .  .  |  /  /  X  |  .  .  .
 *  .  .  |  X  /  /  |  .  .  .
 *  .  .  |  /  /  /  |  .  .  .
 ---------+-----------+---------
 X  /  /  |  X  /  X  |  /  /  /
 *  .  .  |  *  .  *  |  .  .  .
 *  .  .  |  *  .  *  |  .  .  .

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.'
Code: Select all
 *  .  .  |  *  .  *  |  .  .  .
 *  .  .  |  *  .  *  |  .  .  .
 X  /  /  |  X  /  X  |  /  /  /
 ---------+-----------+---------
 *  .  .  |  X  /  X  |  .  .  .
 *  .  .  |  X  /  X  |  .  .  .
 *  .  .  |  X  /  X  |  .  .  .
 ---------+-----------+---------
 X  /  /  |  X  /  X  |  /  /  /
 *  .  .  |  *  .  *  |  .  .  .
 *  .  .  |  *  .  *  |  .  .  .
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re(2): Franken

Postby Pat » Fri Dec 01, 2006 11:01 am

ronk wrote: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 -
Code: Select all
. 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!
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Re: re(2): Franken

Postby Havard » Fri Dec 01, 2006 11:56 am

Pat wrote: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

Pat wrote: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!:) )

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Re: re(2): Franken

Postby ronk » Fri Dec 01, 2006 12:57 pm

Pat wrote: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.
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Postby daj95376 » Wed Dec 06, 2006 12:07 pm

Basic fish question.

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

Code: Select all
# 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?
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Postby Ruud » Wed Dec 06, 2006 1:03 pm

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)

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What is the next step?

Postby ArkieTech » Wed Dec 06, 2006 3:44 pm

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

I can't see a solution or what is next. Help:(
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Re: What is the next step?

Postby ronk » Wed Dec 06, 2006 3:53 pm

ArkieTech wrote: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.
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Postby Carcul » Wed Dec 06, 2006 4:00 pm

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



Code: Select all
 *-----------------------------------------------------*
 | 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.

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Postby ArkieTech » Wed Dec 06, 2006 4:34 pm

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



Thanks Carcul

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

Postby Pat » Mon Dec 11, 2006 3:03 pm

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


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

 ...  ../  ..*
 ...  ../  ..*
 ***  **.  ***

 ***  **.  ..*
 ...  ../  //.
 ...  ../  //.

      the extra exclusions r6c78
      are due to the overlap in the "cover"
      as explained by Mike Barker
Mike Barker (2006.Nov.25) wrote: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.
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Re: (finless) Franken Swordfish, with overlap in "cover

Postby ronk » Mon Dec 11, 2006 4:22 pm

Pat wrote:
      (finless) Franken Swordfish,
      with overlap in "cover"


      ccc\rrb :
      "base" = Columns 6,7,8
      "cover" = Rows 6,7 + Box 6 (note overlap)
Code: Select all
 .  .  . |  .  .  / |  /  /  .
 .  .  . |  .  .  / |  /  /  .
 .  .  . |  .  .  / |  /  /  .
---------+----------+----------
 .  .  . |  .  .  / |  X  X  *
 .  .  . |  .  .  / |  X  X  *
 *  *  * |  *  *  X | *X *X  *
---------+----------+----------
 *  *  * |  *  *  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.
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re: (finless) Franken Swordfish, overlap in "cover"

Postby Pat » Mon Dec 11, 2006 5:26 pm

ronk wrote:The franken x-wing c78b69 would eliminate r456789c9.

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

ronk wrote: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

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Re: re: (finless) Franken Swordfish, overlap in "cover&

Postby ronk » Mon Dec 11, 2006 6:57 pm

Pat wrote:
ronk wrote: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.:)
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