Naxb5

Naxb5 is a term used in chess notation to indicate a knight from the a-file captures a piece on the square b5. It is a disambiguated form of the capture move Nxb5, used when two or more knights can legally move to b5.

The origin of the move is shown in the notation to resolve ambiguity. If the knight from the a-file is the one that makes the capture, the move is written Naxb5. If two knights on the same file could reach b5, the notation may use the originating rank instead, for example Na3xb5 becoming N3xb5 or Na7xb5 becoming N7xb5, depending on the exact placement of the knights. In standard algebraic notation, the minimal disambiguation necessary to identify the moving piece is used.

Example: In a position where White has knights on a3 and c3 and a Black piece occupies b5, White to move would capture with the knight from a3 if the legal capture is available. The move would be written Naxb5, and after the capture the knight would occupy b5. If instead the knight on c3 captured on b5, the move would be Ncb5. The notation may include a plus sign if the capture also gives check, as in Naxb5+.

See also: Nxb5, disambiguation in chess notation, algebraic notation. Naxb5 is specifically a disambiguated capture move for a knight originating from the a-file and targeting b5; its usage is confined to standard chess notation and related literature.