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Sudopedia:Fish diagram

When a solving technique only deals with the candidates for a single digit, it is customary to use the letter X to replace this digit, both in chain notation and in the illustrating diagrams. This abstraction helps the reader understand that this is a single-digit technique and focus on the pattern rather than the pencilmarked candidates.

You are advised to use fish diagrams to illustrate these techniques. These diagrams are based on a text format used in fish-related topics in the Sudoku Players' forum.

Here is an example, illustrating a Finned Swordfish:

This is the same example in the text format used in the forums:

.  /  . | .  /  . | .  /  .
*  X  * | .  X  . | .  X  .
.  F  . | .  /  . | .  /  .
--------+---------+--------
.  /  . | .  /  . | .  /  .
.  X  . | .  X  . | .  X  .
.  /  . | .  /  . | .  /  .
--------+---------+--------
.  /  . | .  /  . | .  /  .
.  X  . | .  X  . | .  X  .
.  /  . | .  /  . | .  /  .

If you do not have the tools to create graphical fish diagrams, use the text version instead. Sooner or later, a helpful Sudopedian will replace it with a graphical version.

Symbols

There are only a few symbolic characters used in fish diagrams.

/ (forward slash)

Cells that do not contain a candidate for digit X. These cells belong to the defining set.

X

Cells that may contain a candidate for digit X. These cells belong to both the defining set and the secondary set.

*

Cells from which the candidates for digit X can be eliminated. These cells only belong to the secondary set.

F

Fin cells. These only belong to the defining set, but are limited to a single house.

. (dot)

Irrelevant cells. These are unmarked in the graphical version of the diagram.

See also

• Fish
• Diagrams and Notations

This page was last modified 21:42, 30 December 2009.  

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