Encoding Centered Polyominoes by Means of a Regular Language

In [3] the authors proposed a classification of convex polyominoes based on the number of changes of direction in the paths connecting any two cells of a polyomino. More precisely, a convex polyomino is k-convex if every pair of its cells can be connected by a monotone path with at most k changes of direction. In 1-convex (also called L-convex) polyominoes, any two cells can be connected by a path with at most one change of direction.