
Finned Mutant Jellyfish 

A Finned Mutant Jellyfish is 4 primary units that contain a candidate only in 4 secondary units, except for one (or more than one if they share a tertiary unit). Please refer to Mutant Jellyfish and Finned Jellyfish. The logic behind this technique is that if the fin is not true, the rest of the Mutant Jellyfish is.
Consider the example on this page. The candidate is 6 and the primary units are rows 3, 5, 7, and the bottomright box. All the 6's in these units have been highlighted in blue. The secondary units are columns 2, 4, 6, and 8. If the bottomright box as a primary unit were substituted for a row this would not be mutant. All the 6's in these primary units can be found within these secondary units, except for one, the middleleft cell of the bottomright box, which is the fin. If the fin is not true, then the mutant jellyfish is true causing the elimination of all the other 6's in columns 2, 4, 6, and 8. If the fin IS true, then it eliminates all other 6's in row 8. Either way, the 6 highlighted in green can be eliminated.
Note as usual that not all fins must be only one cell. Sometimes a fin can extend to several cells that share the same tertiary unit. For instance, if in the example on this page the value 2 were removed from the bottomright box, the candidate 6 would be found therein, and it would still be an extension of the same fin. The logic would then be as follows. If neither of the cells in the fin is true, the Mutant Jellyfish is true. Otherwise, if any of the fin cells is true, we can still make the eliminations hightlighted in green.
Sudoku Snake gives Finned Mutant Jellyfish a skill value of 3500.






