Seebold, PatriceSlowinski, Karine2014-10-212014-10-2119911467-8659http://dx.doi.org/10.1111/1467-8659.1040319With any word over the alphabet ?=r, r?, u, u, we associate a connected picture in the following manner: the reading of each letter of this word induces a unit line: r (r?, u, u respectively) stands for a right (left, up, down respectively) move. We present a rewriting system which can yield, from any word over ?, all the words describing the same picture. Particularly, we give an algorithm to find a minimal word describing a given picture: this word represents the shortest way to draw this picture without penup .10.1111/1467-8659.1040319319-327