Turbot Fish
Points.
A Turbot Fish is a singledigit solving technique that uses a loop of odd
length, where length refers to strong or weak links. The minimum length is
therefore 5 and the minimum number of thruths is 2. Turbot Fish are
chainlike rank 1 structures. The name come from their fishshaped patterns.
Longer loops are possible, but they are better known as Fishy Cycles. Minimum
length Turbot Fish are sometimes called Skyscrapers
or Two Sting Kites. Turbot Fish are rank 1.
Turbot Fish. The first
turbot fish example is also a vertical skyscraper, which works like a very
simple chain. The cover link regions are highlighted showing the overlap
region between box 1 and row 2.
In
terms of implications:
9r2c7
=> r2c3<>9
r2c7<>9
=> 9r8c7 => r8c2<>9 => 9r2c2 => r2c3<>9
In terms of truths and
covers, 2 truths + 3 covers imply any candidate covered by two links can be
eliminated. Thus r2c3<>9. The
elimination region includes all three cells in the intersection of box 1 with row 2.


Box/row Turbot Fish. This
turbot fish again works like a very simple chain. It is different from the
first example becasue it uses a box truth and a row truth.
In terms of truths and
covers, 2 truths + 3 covers imply any candidate covered by two links can be
eliminated. Thus r8c2<>5.


Row/Column Turbot Fish. Example
3 is both a Turbot Fish and a Crossed Two String Kite. It uses a row truth
and a column truth.
In terms of truths and
covers, 2 truths + 3 covers imply any candidate covered by two links can be
eliminated. Thus r8c3<>4.


Length 7 Turbot Fish. A
Turbot Fish with a length of 7 is made of 3 truths and 4 cover links. This
pattern is also known as a Fishy Cycle.
In terms of truths and covers,
3 truths + 4 covers imply any candidate covered by two links can be
eliminated. Thus r9c2<>9.


Fully Grouped Turbot Fish.
A Turbot Fish with a length of 7 is made of 3 truths, all of which are
boxes, and 4 cover links. All of the six connections between truths and
covers are grouped, using more than 1 candidate.
The logic is again simple in
terms of truths and covers, 3 truths + 4 covers means a rank of 1 thus any
candidate covered by two links can be eliminated. Thus r8c5<>2.


