## The Ultimate FISH Guide

Advanced methods and approaches for solving Sudoku puzzles

### Re: The Ultimate FISH Guide

champagne » 24 Apr 2020 20:25
studying the fish guide to have it coded in my program, I got this fish coming in a puzzle from the interactive games
...........12.34...2.1.5.6..75...18...........89...74..6.3.9.5...47.19...........;6.50;4.20;4.00

Mutant Jellyfish: 6 c38b28 r159c5 => r1c12579,r4569c5,r5c124679,r9c1279<>6

Code: Select all
` yzfwsf » 24 Apr 2020 23:27 `
found this with my solver and hodoku { takes more effort - turning on more then 1 elimination per location in the steps menu other wise it will not show up also enabling all fish types other wise the lower priority frank-en cases hit all the eliminations before Mutant is searched}
Some do, some teach, the rest look it up.
stormdoku

StrmCkr

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Joined: 05 September 2006

### Re: The Ultimate FISH Guide

yzfwsf wrote:HI champagne:
For me, when POM can't find the equivalent fish, the solver will go through all combinations and become inefficient, so it is placed in a very low priority, just before force Net.

If I forget that Sudoku Explainer does not use groups of candidates, my TLG is equivalent to a Xloop
for example

6r1c3 - 6r1c456 = 6r2c5 - 6r8c5 = 6r8c456 - 6r9c7 = 6r5c7 - 6r5c3 loop
This gives all eliminations except the cannibalism.

So just considering that a player has already studied the digit pm, I would have seen it around the Jellyfish hardness.
champagne
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Location: France Brittany

### Re: The Ultimate FISH Guide

i use ERI's for x cycles and the group in the box acts as a single cell for the on/off link, which is seen by the 2nd eri and a bilocal from the loop {two truths} so its eliminated tagging the cannibalistic eliminations.
Some do, some teach, the rest look it up.
stormdoku

StrmCkr

Posts: 1336
Joined: 05 September 2006

### Re: The Ultimate FISH Guide

Working on this puzzle rated 4.2 (XWing)

7..2...34......5.2.....567...7..68...8..5....5..9....1..2..9....3..7....4..1....3;4.20;4.20;4.20

Code: Select all
`7     1569 15689  |2     1689   18    |19    3       4    13689 1469 134689 |34678 134689 13478 |5     189     2    12389 1249 13489  |348   13489  5     |6     7       89   ---------------------------------------------------------1239  1249 7      |34    1234   6     |8     2459    59   12369 8    13469  |347   5      12347 |23479 2469    679  5     246  346    |9     2348   23478 |2347  246     1    ---------------------------------------------------------168   1567 2      |34568 3468   9     |147   14568   5678 1689  3    15689  |4568  7      248   |1249  1245689 5689 4     5679 5689   |1     268    28    |279   25689   3    `

I got 2 fish patterns with eliminations at the start

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`. . .  . . .  . 3 .    x . 3  3 3 3  . . .    3 . 3  3 3 .  . . .    3 . .  3 3 .  . . .    3 . 3  3 . 3  3 . .    . . 3  . 3 3  3 . .    . . .  3 3 .  . . .    . 3 .  . . .  . . .    . . .  . . .   . . 3    `

With truths in c3;c6;c7 and links in c5;c6, we have a TLG-1 with uncovered candidates r23c3 and r6c3.
r2c1 is cleared.
This is a mutant swordfish in the fish guide.

The next one is of higher interest and AFAIK is not in the fish guide

Code: Select all
`. . 8  . 8 8  . . .    8 . 8  8 8 8  . 8 .    8 . x  8 x .  . . 8    . . .  . . .  8 . .    . 8 .  . . .  . . .    . . .  . 8 8  . . .    8 . .  8 8 .  . 8 8    8 . 8  8 . 8  . 8 8    . . 8  . 8 8  . 8 .    `

Here the ‘x’ are the candidates to clear.
We have a “tlg rank 0” with a triple point in truths

Truths c1 ; c4 ; c9 ; b3
Links r2 ; r3 ; r7 ; r8

In Allan Barker’s comments in such a situation, the rank 0 is valid only if the triple point is not assigned. In other terms, the eliminations in links is limited to the link hitting the triple point. In the link R3, the 2 cells ‘x’ can be cleared.

This is a general rule that we have many chances to find in a fish pm. Here we have a franken jelly fish, the same could come with a franken swordfish
champagne
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Location: France Brittany

### Re: The Ultimate FISH Guide

My solver found these for the same eliminations
Finned Mutant Jellyfish 8r169c9\c356b9 fr3c9 => r3c35<>8
Sashimi Mutant Jellyfish 8r169b3\c3568 fr3c9 => r3c35<>8
Finned Mutant Jellyfish 8r19c49\c3b289 fr3c9 => r3c35<>8
Sashimi Mutant Jellyfish 8r19c4b3\c38b28 fr3c9 => r3c35<>8
Finned Mutant Jellyfish 8r19c9b5\c356b9 fr3c9 => r3c35<>8
Sashimi Mutant Jellyfish 8r19b35\c3568 fr3c9 => r3c35<>8
Finned Mutant Jellyfish 8r1c149\r78b12 fr3c9 => r3c35<>8
Finned Mutant Jellyfish 8r1c49b7\r78c3b2 fr3c9 => r3c35<>8
Sashimi Franken Jellyfish 8c149b3\r2378 efr3c9 => r3c35<>8
yzfwsf

Posts: 671
Joined: 16 April 2019

### Re: The Ultimate FISH Guide

yzfwsf wrote:My solver found these for the same eliminations...

Hi yzfwsf,

These eliminations are the only possible eliminations in fish mode, I'll have a look to-morrow to all solutions found by your solver, but as usual, we have many ways to find the same eliminations. What Is here of interest for me is the logic applied with one triple point in truths, what was excluded so far from the studied cases on my side;
champagne
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Joined: 02 August 2007
Location: France Brittany

### Re: The Ultimate FISH Guide

Hi again yzfwsf

Code: Select all
`. . 8    . 8 8    . . .    8 . 8    8 8 8    . 8 .    8 . x    8 x .    . . 8    . . .    . . .    8 . .    . 8 .    . . .    . . .    . . .    . 8 8    . . .    8 . .    8 8 .    . 8 8    8 . 8    8 . 8    . 8 8    . . 8    . 8 8    . 8 .    `

Code: Select all
`My solver found these for the same eliminations8r169c9\c356b9 fr3c9 => r3c35<>8`

I see your 4 truths 4 links (if I understand it properly) construction.

r3c9 is not covered here.

How do you explain the eliminations based on this
champagne
2017 Supporter

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Joined: 02 August 2007
Location: France Brittany

### Re: The Ultimate FISH Guide

champagne wrote:
8r169c9\c356b9 fr3c9 => r3c35<>8[/code]

I see your 4 truths 4 links (if I understand it properly) construction.

r3c9 is not covered here.

How do you explain the eliminations based on this

Hi champagne:
r3c9 is a fin, if it is true, then 8r3c35 can be eliminated or false, then the fish will eliminate 8r3c35.
yzfwsf

Posts: 671
Joined: 16 April 2019

### Re: The Ultimate FISH Guide

yzfwsf wrote:Hi champagne:
r3c9 is a fin, if it is true, then 8r3c35 can be eliminated or false, then the fish will eliminate 8r3c35.

Ok thanks, I can now read and understand most of your list.
I know that the fish guide is shown in this way, I prefer to see the rank 1 logic with r3 as link.

Last detail,

Sashimi Franken Jellyfish 8c149b3\r2378 efr3c9 => r3c35<>8

This is equivalent to my post. One overlapping truth.
What means here ef r3c9
champagne
2017 Supporter

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Joined: 02 August 2007
Location: France Brittany

### Re: The Ultimate FISH Guide

ef (endo fin) is similar to the base triple of Allen logic.If the endo fin is false, PM will become a regular fish, otherwise, if the endo fin is true, the eliminations will be generated directly
yzfwsf

Posts: 671
Joined: 16 April 2019

### Re: The Ultimate FISH Guide

champagne wrote:If I forget that Sudoku Explainer does not use groups of candidates, my TLG is equivalent to a Xloop
for example

6r1c3 - 6r1c456 = 6r2c5 - 6r8c5 = 6r8c456 - 6r9c7 = 6r5c7 - 6r5c3 loop
This gives all eliminations except the cannibalism.

So just considering that a player has already studied the digit pm, I would have seen it around the Jellyfish hardness.

X-Cycle: 6r2c5 = r2c1 - r1c3 = r5c3 - r5c7 = r9c7 - r8c9 = 6r8c5 => r5c14569,r1469c5,r1c1,r9c9<>6
yzfwsf

Posts: 671
Joined: 16 April 2019

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