## Is There a Fish ?

Everything about Sudoku that doesn't fit in one of the other sections

### re: eel 34

ronk wrote:
mutant swordfish r39c8\c6b39
fin = r3c8

The unusual thing about this is that b3 would be used twice as a cover sector in Obi-Wahn's "N+1 finless cover notation." I'm afraid mutant swordfish r39c8\c6b339 OR r39c8\c6b39b3 would each lead to confusion.

first, add c79 to both, giving:
r39b6\c679
fin = r3c8
then
r39b6\c679b3

Pat

Posts: 3640
Joined: 18 July 2005

### Re: re: eel 34

Pat wrote:
first, add c79 to both, giving:
r39b6\c679
fin = r3c8
then
r39b6\c679b3

That math would be difficult for most, and making such an effort to redefine the fish makes little sense to me. It's a heck of a lot easier to just write ...

mutant swordfish r39c8\c6b39 plus endofin r3c8

IOW the notation shouldn't determine the fish.
ronk
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Joined: 02 November 2005
Location: Southeastern USA

Without taking away from my original solution to G063, is this alternate solution correct; and, if so, are the fins endo-/exo-/remote/Kraken?

Code: Select all
# mutant Swordfish c58b6/r258 w/fins [r3c8],[r4c9]
*-----------------------------------*
|  6  .  .  |  .  .  .  |  .  .  .  |
|  .  .  .  |  6 *6  6  |  . *6 -6  |
|  .  .  .  |  .  .  6  |  . #6  6  |
|-----------+-----------+-----------|
|  .  .  .  |  6  .  .  |  .  . #6  |
|  .  .  .  |  6 *6  6  | *6  . *6  |
|  .  6  .  |  .  .  .  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  6  |  .  .  .  |  .  .  .  |
|  .  .  .  |  6 *6  6  |  . *6  .  |
|  .  .  .  |  .  .  6  |  6  .  .  |
*-----------------------------------*
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

daj95376 wrote:Without taking away from my original solution to G063, is this alternate solution correct; and, if so, are the fins endo-/exo-/remote/Kraken?

Code: Select all
# mutant Swordfish c58b6/r258 w/fins [r3c8],[r4c9]
*-----------------------------------*
|  6  .  .  |  .  .  .  |  .  .  .  |
|  .  .  .  |  6 *6  6  |  . *6 -6  |
|  .  .  .  |  .  .  6  |  . #6  6  |
|-----------+-----------+-----------|
|  .  .  .  |  6  .  .  |  .  . #6  |
|  .  .  .  |  6 *6  6  | *6  . *6  |
|  .  6  .  |  .  .  .  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  6  |  .  .  .  |  .  .  .  |
|  .  .  .  |  6 *6  6  |  . *6  .  |
|  .  .  .  |  .  .  6  |  6  .  .  |
*-----------------------------------*

Nice alternative, and it's just as simple as the other IMO.

Both fins are "exo-fins" -- candidates in the base sectors but outside the cover sectors, i.e., uncovered base candidates. But just the word "fin" is perfectly acceptable most of the time. The term "exo-fin" was coined so that there could be an answer to the question ... "When it's not an endo-fin, what type of fin is it?"

http://forum.enjoysudoku.com/viewtopic.php?p=40688#p40688

If one of your fin cells didn't directly "see" the elimination cell, then it would be a "remote fin" -- or "remote exo-fin." See the link above for "endo-fin."
ronk
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Joined: 02 November 2005
Location: Southeastern USA

### re(2): eel 34

ronk wrote:the notation shouldn't determine the fish

sorry but i'm lost as to your meaning ?

the Franken Swordfish rrb\ccc
is equivalent to the Mutant Swordfish rrc\cbb
( and the fin is the same )
one could see the equivalence in the diagrams
( or just add those two columns --
the way Obi-Wahn explained about equivalent fish )

Pat

Posts: 3640
Joined: 18 July 2005

### Re: re(2): eel 34

Pat wrote:
ronk wrote:the notation shouldn't determine the fish

sorry but i'm lost as to your meaning ?

I mean that an awkward notation like ... mutant swordfish r39c8\c6b39b3 ... shouldn't create a necessity to find an alternate fish with a less awkward notation like ... franken swordfish r39b6\c679b3.

Pat wrote:
first, add c79 to both, giving:
r39b6\c679
fin = r3c8
then
r39b6\c679b3

Mathematically, it takes a little more than "add c79 to both".

Make c789 = b369 substitution on the left
Subtract b39\b39 from both sides

r39c8\c6b39(b3) + c79\c79 = r39c789\c679b39(b3) = r39b369\c679b39(b3) - b39\b39 = r39b6\c679b3
ronk
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Posts: 4764
Joined: 02 November 2005
Location: Southeastern USA

ravel just posted these in another thread. They're essentially identical, but that's not the point.

Code: Select all
120406700407109000069720100206900450040000000900205610030000000602300070794502360
120406700407109000069720100206900450000000000900245610030000000602300070794502360

I thought I'd post this for the fishermen.

Code: Select all
*--------------------------------------------------------------------------------------*
|  1        2        358     |  4        358      6       |  7        389      359-8   |
|  4        58       7       |  1        358      9       |  258      238      6       |
|  358      6        9       |  7        2        38      |  1        34-8     45      |
|----------------------------+----------------------------+----------------------------|
|  2        178      6       |  9        137-8    1378    |  4        5        378     |
|  35-8     4        135-8   |  68       167-8    137-8   |  289      2389     2379-8  |
|  9        78       38      |  2        4        5       |  6        1        378     |
|----------------------------+----------------------------+----------------------------|
|  58       3        15-8    |  68       1679-8   147-8   |  259-8    249-8    12459-8 |
|  6        158      2       |  3        19-8     14-8    |  589      7        149-8   |
|  7        9        4       |  5        18       2       |  3        6        18      |
*--------------------------------------------------------------------------------------*

*-----------------------------------*
|  .  .  8  |  .  8  .  |  .  8 -8  |
|  .  8  .  |  .  8  .  |  8  8  .  |
|  8  .  .  |  .  .  8  |  . -8  .  |
|-----------+-----------+-----------|
|  .  8  .  |  . -8  8  |  .  .  8  |
| -8  . -8  |  8 -8 -8  |  8  8 -8  |
|  .  8  8  |  .  .  .  |  .  .  8  |
|-----------+-----------+-----------|
|  8  . -8  |  8 -8 -8  | -8 -8 -8  |
|  .  8  .  |  . -8 -8  |  8  . -8  |
|  .  .  .  |  .  8  .  |  .  .  8  |
*-----------------------------------*
daj95376
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Posts: 2624
Joined: 15 May 2006

SSTS didn't do r3c9<>8 so it's added back in. Then 13 of the 18 eliminations are explained by an unfinned mutant swordfish. The unexplained eliminations (which I didn't try for) are shown as 'U8'.
Code: Select all
.  .  8  |  /  8  .  |  .  8 -8
.  8  .  |  /  8  .  |  8  8  .
8  .  .  |  /  .  8  |  . U8 -8
----------+-----------+----------
.  8  .  |  / U8  8  |  /  /  8
-8  . -8  |  8 -8 -8  |  8  8 -8
.  8  8  |  /  .  .  |  /  /  8
----------+-----------+----------
8  . U8  |  8 -8 -8  | U8 U8 -8
.  8  .  |  . -8 -8  |  8  . -8
/  /  /  |  /  8  .  |  /  /  8

unfinned mutant swordfish r9c4b6\r5c9b8
ronk
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Location: Southeastern USA

ronk, 13 of 18 is great!!! Thanks for the lesson!
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

Ignoring the 2-String Kite for the moment, did I correctly identify this fish?

Code: Select all
# finned Franken Swordfish r27b5\c346 w/fin cell [r7c5]
*-----------------------------------*
|  .  .  .  |  .  .  .  |  .  5  .  |
|  .  . *5  |  .  . *5  |  .  .  .  |
|  5  5  .  |  .  5  5  |  .  .  .  |
|-----------+-----------+-----------|
|  5  .  5  | *5  . *5  |  .  .  .  |
|  .  .  .  |  .  .  .  |  .  .  5  |
|  .  5  5  | *5  . *5  |  .  .  .  |
|-----------+-----------+-----------|
|  .  . *5  | *5 #5 *5  |  .  .  .  |
|  .  .  .  | -5  5  .  |  5  .  .  |
|  5  .  .  | -5  . -5  |  5  .  .  |
*-----------------------------------*
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

Maybe the fishermen will find this a challenge.

Code: Select all
*-----------------------*
| . 3 2 | 8 . . | . . . |
| . . 1 | . 3 . | . 8 . |
| 4 5 8 | . 2 9 | . . . |
|-------+-------+-------|
| . 9 . | . . 2 | . . . |
| . 2 5 | 3 6 8 | 9 4 . |
| . . . | 4 . . | . 2 . |
|-------+-------+-------|
| . . . | 9 4 . | 2 1 8 |
| . 1 . | . 8 . | 4 . . |
| . . . | . . 1 | 3 6 . |
*-----------------------*

Code: Select all
*--------------------------------------------------------------*
|  67    3     2     |  8     157   567   |  1567  9     4     |
|  9     67    1     |  567   3     4     |  567   8     2     |
|  4     5     8     |  167   2     9     |  167   37    1367  |
|--------------------+--------------------+--------------------|
|  367   9     4     |  157   17    2     |  8     357   3567  |
|  17    2     5     |  3     6     8     |  9     4     17    |
|  1367  8     67    |  4     9     57    |  167   2     1356  |
|--------------------+--------------------+--------------------|
|  5     67    367   |  9     4     367   |  2     1     8     |
|  2     1     3679  |  567   8     367   |  4     57    579   |
|  8     4     79    |  2     57    1     |  3     6     579   |
*--------------------------------------------------------------*

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  .  .  |
|-----------+-----------+-----------|
|  . -7  7  |  .  .  7  |  .  .  .  |
|  .  .  7  |  7  .  7  |  .  7  7  |
|  .  .  7  |  .  7  .  |  .  .  7  |
*-----------------------------------*
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

Maybe this one will be interesting.

Code: Select all
*-----------------------*
| . . 1 | . . 9 | 5 . 3 |
| . . . | . . . | . . . |
| . 8 . | 1 6 5 | . 4 . |
|-------+-------+-------|
| 9 . . | 6 . . | 8 . . |
| . . . | 9 4 1 | . . . |
| . . 6 | . . 8 | . . 5 |
|-------+-------+-------|
| . 4 . | 2 8 6 | . 5 . |
| . . . | . . . | . . . |
| 8 . 3 | 7 . . | 9 . . |
*-----------------------*

Code: Select all
*--------------------------------------------------------------*
|  4     267   1     |  8     27    9     |  5     267   3     |
|  267   9     5     |  4     3     27    |  1267  167   8     |
|  3     8     27    |  1     6     5     |  27    4     9     |
|--------------------+--------------------+--------------------|
|  9     237   4     |  6     5     27    |  8     1237  127   |
|  5     237   8     |  9     4     1     |  267   2367  267   |
|  127   127   6     |  3     27    8     |  4     9     5     |
|--------------------+--------------------+--------------------|
|  17    4     9     |  2     8     6     |  3     5     17    |
|  1267  1267  27    |  5     9     3     |  17    8     4     |
|  8     5     3     |  7     1     4     |  9     26    26    |
*--------------------------------------------------------------*

Code: Select all
*-----------------------------------*
|  . -2  .  |  .  2  .  |  .  2  .  |
|  2  .  .  |  .  .  2  |  2  .  .  |
|  .  .  2  |  .  .  .  |  2  .  .  |
|-----------+-----------+-----------|
|  .  2  .  |  .  .  2  |  . -2 -2  |
|  . -2  .  |  .  .  .  |  2  2  2  |
|  2  2  .  |  .  2  .  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  .  |  2  .  .  |  .  .  .  |
|  2  2  2  |  .  .  .  |  .  .  .  |
|  .  .  .  |  .  .  .  |  .  2  2  |
*-----------------------------------*

Note: [r5c7]=2 => all eliminations for <2>. Ironically, [r5c7]<>2 in the solution.

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  |
|  7  7  7  |  .  .  .  |  7  .  .  |
|  .  .  .  |  7  .  .  |  .  .  .  |
*-----------------------------------*
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

Potpourri.

Code: Select all
*-----------------------*
| 8 . . | . . . | . . . |
| . 7 1 | 2 8 . | . 3 . |
| . 2 4 | . . 7 | . 8 . |
|-------+-------+-------|
| 4 . . | . . . | 2 1 . |
| 7 . . | 8 . 2 | . . 6 |
| . 1 2 | . . . | . . 7 |
|-------+-------+-------|
| . 5 . | 6 . . | 4 2 . |
| . 4 . | . 5 8 | 6 7 . |
| . . . | . . . | . . 8 |
*-----------------------*
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

daj95376 wrote:Ignoring the 2-String Kite for the moment, did I correctly identify this fish?

Yes you did.

daj95376 wrote:Maybe the fishermen will find this a challenge.
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  .  .  |
|-----------+-----------+-----------|
|  . -7  7  |  .  .  7  |  .  .  .  |
|  .  .  7  |  7  .  7  |  .  7  7  |
|  .  .  7  |  .  7  .  |  .  .  7  |
*-----------------------------------*

This fish was definitely a challenge. With three fins including an endo-fin and two of the fins requiring chains, the fish I caught by hand is an ugly one. I wonder if Obi-Wahn's or Mike Barker's programs could find a prettier one.

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  .  .
---------+----------+----------
. *7 *7 |  .  . *7 |  .  .  .
.  . *7 |  7  . *7 |  .  7  7
.  / @7 |  . *7  / |  /  / *7

mutant whale r359c236\c9b23478 plus fins r2c2, r6c6 and endo-fin r9c3, implies r2c47<>7

Either the whale or at least one of the fins must ultimately be true:
• finless whale r359c236\c9b23478-7-r2c47
• fin r2c2-7-r2c47
• remote fin r6c6-7-r6c13=7=r45c1-7-r1c1=r2c2-7-r2c47
• remote endo-fin r9c3-7-r6c3=7=r456c1-7-r1c1=r2c2-7-r2c47
Since r9c3 is in the intersection of the two base sectors r9 and c3, it is called an endo-fin. Even though it is covered by b7, it must also be treated separately as a fin.

If one is satisfied with only one elimination at a time, there are likely smaller fish to be found.
ronk
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Posts: 4764
Joined: 02 November 2005
Location: Southeastern USA

This thread seems to have a mind of its own. First ronk posted a reply and then it disappeared. Then I added two more puzzles and ronk's message re-appeared. I just noticed a reply from Mike Barker and, POOF, it disappeared. Well, I think I'll answer Mike's question even though his post is gone.

I have a puzzle generator that generates a random filled grid. I then eliminate cell pairs and solve the results. I restrict the solution techniques allowed, and I use a (horrible) weighting technique to compare one cell pair to another for desirability to be eliminated. This process continues until I can't eliminate any more cell pairs. I then save this puzzle with its weight value. I perform this operation several times for the filled grid -- starting with a random cell pair and saving the resultant puzzle with the highest weight attained.

When I'm done, the resulting puzzle is guaranteed to be solvable with the techniques I allow. However, the quality of the puzzle is also limited by the random distribution of values in the initial filled grid.

The techniques for my last three puzzles are: Naked/Hidden N-Tuples, Locked Candidates 1 & 2, X-Wing, Swordfish, Jellyfish, XY-Wing, XYZ-Wing, BUG+1, Unique Rectangle Type 1, and Templates.

I then run the resulting puzzles through my solver where it detects finned and Sashimi fish -- along with a few other single-digit patterns. Finally, since I don't have Colors and Multiple Colors implemented yet, I run the puzzles through Simple Sudoku.

The posted puzzles are those that still have Template eliminations remaining. You are correct that not all eliminations need to be performed by one fish. A fish combined with subsequent single-digit operations may be the best choice. However, I'm forced to post all eliminations because I don't know which of them might be eliminated subsequently.
daj95376
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Posts: 2624
Joined: 15 May 2006

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