page_title: Slitherlink
section_title: Notation
hierarchical_section_title: Slitherlink / Solution methods / Notation
context_page_description: Slitherlink is a logic puzzle developed by publisher Nikoli.
context_section_description: Whenever the number of lines around a cell matches the number in the cell, the other potential lines must be eliminated. This is usually indicated by marking an X on lines known to be empty.
  Another useful notation when solving Slitherlink is a ninety degree arc between two adjacent lines, to indicate that exactly one of the two must be filled. A related notation is a double arc between adjacent lines, indicating that both or neither of the two must be filled. These notations are not necessary to the solution, but can be helpful in deriving it.
  Many of the methods below can be broken down into two simpler steps by use of arc notation.
caption: Arc notation around a 2 in a corner.
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