Historical notesThe Crab is a kind of `restricted knight', introduced by Ralph Betza in 1996. The name is clear from the diagram: the squares the crab can go to are like the pincers of a crab.
MovementThe crab moves like a knight, jumping across squares, but only in some directions: it can go either two squares vertically forwards and one square horizontally, or one square vertically backwards and two squares horizontally.
Movement diagramThe crab can jump to all the squares marked with a circle.
The Crab cannot inflict checkmate on a rectangular board with only assistance of its own King, and is thus a minor piece. Even with a pair of Crabs you cannot force checkmate on a bare King, but paired with another minor this is sometimes possible. But because the Crab is so weak, and can make the necessary manouevre only in two of the corners because of its assymmetry, this succeeds only on small boards if the partner piece is not stronger than an 8-target leaper. Try it!
This is an item in the Piececlopedia: an overview of different (fairy) chess pieces.
Written by Hans Bodlaender.
WWW page created: March 20, 2001.