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When [[fish]] are no longer restricted to [[row]]s and [[column]]s, strange varieties emerge. When either the [[defining set]] or the [[secondary set]] contains a mixture of rows, columns and/or [[box]]es, these fish are classified as '''mutant fish'''.

There are no mutant [[X-Wing]]s, because the interaction between a single box and line is fully covered by the [[Locked Candidates]] technique.

Here is a [[project:fish diagram|fish diagram]] of a [[Mutant Swordfish]], with the [[defining set]] consisting of 2 rows and 1 column, and the [[secondary set]] containing 1 column and 2 boxes.

[[Image:mutant swordfish.png]]

Mutant fish can also be found in [[fin]]ned variations.

'''The 5 Mutant swordfish patterns'''

The previous example is the maximum pattern for the mutant swordfish. It consists of 10 cells with 3 group conjugates in rows 1 and 9 and column 7. Fortunately, 4 of the 10 cells in the maximum pattern are redundant. If a candidate is removed from a single cell of any or all of the 4 row and column groups in box 3 and 9, the pattern will still work. Therefore there are 5 patterns for the mutant swordfish with 6, 7, 8, 9, and 10 cells. This is analogous to the 4 patterns of the row or column swordfish with 6, 7. 8. or 9 cells. The maximum pattern is by far the rarest of the 5 patterns.

'''Minimum Pattern for the Mutant Swordfish'''

The minimum mutant swordfish pattern, which contains only 6 cells is shown in the diagram below. Here all of the group conjugates in the previous example become conjugate pairs.

{{grid|1=--|2=A|3=--|4=--|5=--|6=--|7=--|8=C|9=--|11=*|16=E|17=*|18=*|20=*|25=--|26=*|27=*|29=*|34=--|38=*|43=--|47=*|52=--|56=*|61=--|62=*|63=*|65=*|70=F|71=*|72=*|73=--|74=B|75=--|76=--|77=--|78=--|79=--|80=--|81=D}}

'''How it works'''
There are 3 sets of conjugate pairs in the pattern, AC, BD, and EF. For each of these, one cell must be X and the other must be not X. If A is X, its conjugate C must be not X and there can be no other X in column 2 including B. Therefore B's Conjugate D must be X and and there can be no other X in box 9 including F. Therefore F's conjugate E must be X and there can be no other X in box 3. If B is X, its conjugate D must be not X and there can be no other X in column 2 including A. Therefore A's Conjugate C must be X and and there can be no other X in box 3 including E. Therefore E's conjugate F must be X and there can be no other X in box 9.

'''A Finned Mutant Swordfish Example'''

An example of a finned mutant swordfish is shown in the diagram below, The fin appears at r1c7 in box 3. Note this is the only cell where a fin can be located in box 3 since the other cells in box 3 row 1 and column 7 are part of the pattern. The 4 candidate elimination cells also occur in box 3.

{{grid|1=--|2=X|3=--|4=--|5=--|6=--|7=X|8=X|9=--|16=X|17=*|18=*|25=--|26=*|27=*|34=--|43=--|52=--|61=--|70=X|73=--|74=X|75=--|76=--|77=--|78=--|79=--|80=--|81=X}}

== See Also ==
* [[Fish]]
* [[Franken Fish]]
* [[Mutant Swordfish]]
* [[Mutant Jellyfish]]

[[Category:Solving Techniques]]
[[Category:Single-Digit]]

Mutant Fish - Revision history

Rooted: Created page with "When fish are no longer restricted to rows and columns, strange varieties emerge. When either the defining set or the secondary set contains a mixture of r..."