The Fin is extra cells in a row or column containing the candidate being considered with all the extra cells contained in a single box.

A Finned Fishy Thing only allows the elimination of candidates from cells that are in the same box as the fin and would have had candidates eliminated if the Fishy Thing did not have the fin.Figure 1 shows a

With a Finned X Wing pattern there are two possible solutions. The value 3 will eventually be placed in one of the fin cells (In this case the single green cell) or, if the 3 is not placed in one of the fin cells the X Wing pattern would be valid. In either case the value 3 can be eliminated from cells in the box containing the fin that would have been eliminated if the fin did not exist.

Having the fin on this X Wing does not allow the elimination of the value 3 from the yellow cells that would have been possible if it was a real X Wing.Figure 2 shows another example of a

Either the 7 has to be placed in one of the green cells or the the X Wing pattern shown as blue cells will be valid. Either of these two possibilities will remove the 7 from the grey cell.Figure 3 shows an example of a

Either way the 3 will be eliminated from the grey cell.And just because it is there, the same puzzle contains a

Either way the value 3 will be eliminated from the grey cell.

Sudoku Rules and Techniques

Sudoku Rules

Acknowledgments

I would like to acknowledge these sites referenced for strategy ideas and solving techniques.

SudokuWiki.Org by Andrew Stuart

PaulsPages.co.uk by Paul Stevens

Sudoku Rules

Cross Hatching

Counting

Naked Set

Hidden Set

Claiming

Remote Pairs

X Wing

XY Wing

Simple Coloring

Fishy Things

Unique Rectangle

X Chain

Aligned Pair Exclusion

Forcing Chains

Finned Fishy Things

Almost Locked Sets

Counting

Naked Set

Hidden Set

Claiming

Remote Pairs

X Wing

XY Wing

Simple Coloring

Fishy Things

Unique Rectangle

X Chain

Aligned Pair Exclusion

Forcing Chains

Finned Fishy Things

Almost Locked Sets

Acknowledgments

I would like to acknowledge these sites referenced for strategy ideas and solving techniques.

SudokuWiki.Org by Andrew Stuart

PaulsPages.co.uk by Paul Stevens