Big fish

Advanced methods and approaches for solving Sudoku puzzles

Postby vidarino » Tue Mar 14, 2006 12:30 pm

I should probably let this go, but how about this one? (I'm far from sure that it's the real deal, but I can't find an alternative smaller fish here...)

Code: Select all
 567    2456   247    |  1      8      467    | -4567   9      3
*1678   468   *3      |  5     *2479  *4679   | *1468  #267   #478
*15678  9     *147    |  3     *247   *467    | *14568 #267   #4578
----------------------+-----------------------+-----------------------
*138    238   *12     |  6     *47    *38     | *47     5      9
 4      7      5      |  89     39     2      |  68     36     1
 368    368    9      |  47     1      5      |  2      37     48
----------------------+-----------------------+-----------------------
*39     34    *8      |  2     *4579  *479    | *57     1      6
 2      1      6      |  78     35     38     |  9      4      57
*579    45    *47     |  49    *6     *1      | *3      8      2

Finned Squirmbag with 7 in R23479C13567 + fin R23C89
   -> R1C7 <> 7


Filtered and prettified:
Code: Select all
 7  .  7  |  .  .  7  |  *  .  .
 7  .  x  |  .  7  7  |  x  #  #   <
 7  .  7  |  .  7  7  |  x  #  #   <
----------+-----------+----------
 x  .  x  |  .  7  x  |  7  .  .   <
 .  7  .  |  .  .  .  |  .  .  .
 .  .  .  |  7  .  .  |  .  7  .
----------+-----------+----------
 x  .  x  |  .  7  7  |  7  .  .   <
 .  .  .  |  7  .  .  |  .  .  7
 7  .  7  |  .  x  x  |  x  .  .   <

x="virtual" cells, #=fin,  *=elim
Fishy rows highlighted with '<'


Now, this means that there should exist a Finned Jellyfish in columns, having the same fin and performing the same elimination;
Code: Select all
 7  .  7  |  .  .  7  |  *  .  .
 7  .  .  |  .  7  7  |  .  #  #
 7  .  7  |  .  7  7  |  .  #  #
----------+-----------+----------
 .  .  .  |  .  7  .  |  7  .  .
 .  7  .  |  .  .  .  |  .  .  .
 .  .  .  |  7  .  .  |  .  7  .
----------+-----------+----------
 .  .  .  |  .  7  7  |  7  .  .
 .  .  .  |  7  .  .  |  .  .  7
 7  .  7  |  .  .  .  |  .  .  .


Since the elimination happens in row 1, that means (as far as I can tell) that at least one of the columns 1, 3 or 6 must be involved. (Reasoning; If none of the fin cells are 7, we should end up with a plain old Jellyfish doing the elimination instead.)

However, no matter which one I pick, I can't make a set of 4 columns that end up with a 4x4 grid.

So, is this finally the real deal, or is all this salt water getting to me?:)

Vidar
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Postby Havard » Tue Mar 14, 2006 12:42 pm

here you go: Finned Swordfish.
Code: Select all
 
 .  .  .  | (X) .  .  |  * (X)(X)
 .  .  .  |  .  .  .  |  .  #  #
 .  .  .  |  .  .  .  |  .  #  #
----------+-----------+-----|--|-
 .  .  .  |  .  .  .  |  .  |  |
 .  .  .  |  .  .  .  |  .  |  |
 .  .  .  |  7  .  .  |  .  7  |
----------+--|--------+--------|-
 .  .  .  |  |  .  .  |  .  .  |
 .  .  .  |  7  .  .  |  . (X) 7
 .  .  .  |  .  .  .  |  .  .  .


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Postby vidarino » Tue Mar 14, 2006 12:53 pm

Hmm, is that a fish at all? It has *no* cells in row 1 / box 3.

I have no problem with the elimination, though. It's a perfectly fine grouped continuous X-cycle;
R6C4-7-R6C8=7=R23C8-7-R23C9=7=R8C9-7-R8C4=7=R6C4
(edit: ... or a discontinuous one;)
R1C7-7-R23C9=7=R8C9-7-R8C4=7=R6C4-7-R6C8=7=R23C8-7-R1C7
... but is it really seafood?


I've used the following reasoning to explain finned fish;
a) One of the fin cells is true, and you can do the elimination since they share a box.
b) None if the fins are true, and you end up with a plain, unfinned N-fish doing the elimination instead.
In this case, that's not possible, since if none of the fins were true, the R1C7 would be the only 7 left in the box...

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Postby tarek » Tue Mar 14, 2006 1:00 pm

I think Havard is correct on this one......

Code: Select all
 567    2456   247    | ^1      8      467    | -4567  ^9     ^3
 1678   468    3      |  5      2479   4679   |  1468  #267   #478
 15678  9      147    |  3      247    467    |  14568 #267   #4578
----------------------+-----------------------+-----------------------
 138    238    12     |  6      47     38     |  47     5      9
 4      7      5      |  89     39     2      |  68     36     1
 368    368    9      | ^47     1      5      |  2     ^37     ^48
----------------------+-----------------------+-----------------------
 39     34     8      |  2      4579   479    |  57     1      6
 2      1      6      | ^78     35     38     |  9     ^4     ^57
 579    45     47     |  49     6      1      |  3      8      2


This formation of basically no true vertices in a line (here Row 1) is something that I did not see before.......

Another thing to add to the Arsenal.....

From a programmer's point of view this means that ANY cell on the grid (except the one's seeing a single) are potentially vertices....wierd

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Postby Havard » Tue Mar 14, 2006 1:07 pm

well, it sure tastes like fish to me!

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Postby ravel » Tue Mar 14, 2006 1:22 pm

vidarino wrote:b) None if the fins are true, and you end up with a plain, unfinned N-fish doing the elimination instead.

Seeing it this way means that non existing candidates can kick off an existing one - nice:) (i am arguing differently: after elimination of the fins you are left with candidates in 2 rows for 3 columns)
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Postby vidarino » Tue Mar 14, 2006 1:26 pm

So, in that case, it's actually a 2-1-1 Swordfish...

Anyway, I'm seriously considering disagreeing to calling it a finned fish, until further notice. Straight from the horse's mouth (No offense, MJ):)
Myth Jellies wrote:Filet-O-Fish Rule

If you can form a swordfish/x-wing pattern by not considering candidates in cells (1..n), then you can keep any eliminations from that swordfish/x-wing pattern that share a group with all cells (1..n). The cells (1..n) have been called the fin.


So maybe it's something else entirely... (Edit: offal?:) )

It will certainly be a small b*tch to add to my solver, for sure... (Or perhaps I should just let it go and let the X-Cycle bit pick it up... ;-) )

Vidar
Last edited by vidarino on Tue Mar 14, 2006 9:46 am, edited 1 time in total.
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Postby ronk » Tue Mar 14, 2006 1:37 pm

tarek wrote:This formation of basically no true vertices in a line (here Row 1) is something that I did not see before.......

Another thing to add to the Arsenal.....


[edit: Oops, I see vidarino already posted this same point. Oh well.]

But is r1c7<>7 a valid exclusion of your "finned fish" ... or is it coincidence because it's a valid grouped coloring exclusion ...
Code: Select all
 7 . 7 | . . 7 | 7 . .
 7 . . | . 7 7 | . A a 
 7 . 7 | . 7 7 | . A a 
-------+-------+-------
 . . . | . 7 . | 7 . .
 . 7 . | . . . | . . .
 . . . | A . . | . a .
-------+-------+-------
 . . . | . 7 7 | 7 . .
 . . . | a . . | . . A
 7 . 7 | . . . | . . .

... since r1c7 sees *all* of grouped 'A' and *all* of grouped 'a' in box 3?

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Postby Havard » Tue Mar 14, 2006 2:28 pm

Why not just define a finned swordfish where two of the lines are in the same box like this:
Code: Select all
. . . | . . . | x x .
. . . | . X . | x x *
. . . | . | . | x x .
------+---|---+-|-|--
. . . | . | . | | | .
. . . | . X . | X X .
. . . | . | . | | | .
------+---|---+-|-|--
. . . | . | . | | | .
. . . | . | . | | | .
. . . | . X . | X X .
You can remove one X from each line, and any number of x's and the elimination is still valid!


and for the special case of the fishes "head" not being present, you can do the following eliminations. (in true, old, swordfishstyle!)

Code: Select all
. . . | . . . | x x *
. . . | .(X). | x x *
. . . | . | . | x x *
------+---|---+-|-|--
. . . | . | . | | | .
* * * | * X * | X X *
. . . | . | . | | | .
------+---|---+-|-|--
. . . | . | . | | | .
. . . | . | . | | | .
* * * | * X * | X X *


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Postby ronk » Tue Mar 14, 2006 3:09 pm

Havard wrote:Why not just define a finned swordfish where two of the lines are in the same box like this:

...................

and for the special case of the fishes "head" not being present, you can do the following eliminations. (in true, old, swordfishstyle!)

Why not? The "finned-fish" technique is an outgrowth of Myth Jellies' Pattern-Overlay-Method (POM), and I think the definition of finned-fish ought to stay true to that origin. Maybe your POV *is* covered by POM, but very few on this forum know POM well enough to say whether or not that's the case. MJ and vidarino most likely can, but I can't.

So, limited by my minimal knowledge of POM, I think both of your illustrations properly belong in the general category of grouped x-cycles ... or grouped coloring ... or maybe something else.

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Postby tarek » Tue Mar 14, 2006 3:19 pm

ronk wrote:
tarek wrote:This formation of basically no true vertices in a line (here Row 1) is something that I did not see before.......

Another thing to add to the Arsenal.....


But is r1c7<>7 a valid exclusion of your "finned fish" ... or is it coincidence because it's a valid grouped coloring exclusion ...


Some more examples probably would calrify this. most of these fishes if not all can be explained by some form of colouring.

Havard wrote:and for the special case of the fishes "head" not being present, you can do the following eliminations. (in true, old, swordfishstyle!)
Code: Select all
. . . | . . . | x x *
. . . | .(X). | x x *
. . . | . | . | x x *
------+---|---+-|-|--
. . . | . | . | | | .
* * * | * X * | X X *
. . . | . | . | | | .
------+---|---+-|-|--
. . . | . | . | | | .
. . . | . | . | | | .
* * * | * X * | X X *

I've seen something similar before here. The swordfish Seppuku

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Postby Havard » Tue Mar 14, 2006 3:50 pm

ronk wrote:Why not? The "finned-fish" technique is an outgrowth of Myth Jellies' Pattern-Overlay-Method (POM), and I think the definition of finned-fish ought to stay true to that origin. Maybe your POV *is* covered by POM, but very few on this forum know POM well enough to say whether or not that's the case. MJ and vidarino most likely can, but I can't.


To me, fins got nothing to do with POM. I don't even know what POM is.
For the simplest case, the finned x-wing, all cases can be explained as either a Turbot Fish or a grouped x-cycle.

this is the way I see it:
http://forum.enjoysudoku.com/viewtopic.php?p=23272#p23272

and that way of thinking about it was inspired by Myth Jellies in this post:
http://forum.enjoysudoku.com/viewtopic.php?p=20806#p20806

if you can't accept that we will just have to agree to disagree.

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Postby ronk » Tue Mar 14, 2006 4:01 pm

Havard wrote:
ronk wrote:Why not? The "finned-fish" technique is an outgrowth of Myth Jellies' Pattern-Overlay-Method (POM), and I think the definition of finned-fish ought to stay true to that origin.

To me, fins got nothing to do with POM. I don't even know what POM is.

You apparently missed this thread.

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Postby tarek » Tue Mar 14, 2006 5:35 pm

To test the theory of abscent vertices, the simplest of examples should be enough........

Are any of the the following eliminations valid (the *), it doesn't look valid, but if it is, I would be very happy:D

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


Well obviously it is as X is a hidden single in column 5

what follows r8c8<>x => r3c8=x & hence the eliminations.........

So we will not see this pattern for a finned x-wing........

The search contiues........

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Postby tarek » Tue Mar 14, 2006 5:59 pm

Testing the actual example:
Code: Select all
 . . . | . . . | * . . 
 . . . | . . . | . X X 
 . . . | . . . | . X X 
-------+-------+------
 . . . | . . . | . . . 
 . . . | . . . | . . . 
 . . . | X . . | . X . 
-------+-------+------
 . . . | . . . | . . . 
 . . . | X . . | . . X 
 . . . | . . . | . . . 

Code: Select all
r6c4=x:  r6c8<>x => box line interaction r1c7<>x
r6c4<>x: r8c4=x => r8c9<>x => box line interaction r1c7<>x
Therefore r1c7<>x


so it does still hold.........

The search continues

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