udosuk wrote:"r9c1<>" what? And sorry I don't see a strong link [r6c9]=8=[r1c9]... When did you eliminate the 8 from r2c9?

Oops, forgot to mention what I eliminated... Should of coure be r9c1<>1. The 8 from r2c9 gets eliminated by locked candidates after the earlier elimination r1c1<>28.

udosuk wrote:Same here! Why is there a strong link [r78c8]=1=[r3c8]? What about the 1 in r2c8?

Ah, mistake when writing the chain. Should be the other way around:

[r2c1]-1-[r3c3]=1=[r3c8]-1-[r78c8]=1=[r8c9]

Silly that I didn't happen to spot the shorter version [r2c1]-1-[r2c9]=1=[r8c9], same as the previous eliminations of candidate 1...

Then to define some emerald seafood:

Note: Digit 5 is very special in Emerald bay and is not affected by these rules.

Emerald Eel

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`...|...|...`

-..|...|..a

...|...|...

---+---+---

...|...|...

...|...|...

...|...|...

---+---+---

...|...|...

-..|...|..a

...|...|...

If there is a strong link on candidate A between to symmetrically placed cells in a row or column r(x)c(y), r(10-x)c(y), then we may eliminate candidate A from r(x)c(10-y) and r(10-x)(10-y) and it's symmetrical opposite 10-A from r(x)c(y) and r(10-x)c(y).

Emerald Turbot fish

- Code: Select all
`...|...|..a`

...|...|...

...|...|...

---+---+---

...|...|...

...|...|...

..-|...|..a

---+---+---

...|...|...

...|...|...

a.a|...|...

If there is two strong links on digit A that have one end in symmetrically opposite cells r(x)c(y), r(10-x)c(10-y) Then you may eliminate A from all cells that can see both the other cells of the strong links.

I apparently didn't use the full power of the Eel in my solution (second step, r8c1<>1). Same pattern of course also eliminates 1 from r2c1 and makes my last move unnecessary. After both eliminations by the Eel, the puzzle advances to a state where the puzzle solves with an Emerald Turbot fish on digits 2 and 8.

RW