Homotopy in two-dimensional digital images
We recall the basic definitions concerning homotopy in 2D Digital Topology, and we set and prove several results concerning homotopy of subsets. Then we introduce an explicit isomorphism between the fundamental group of a 2D connected object and a (non-abelian) free group. As a consequence, we provide an algorithm for deciding whether two closed path are homotopic. (C) 2000 Elsevier Science B.V. All rights reserved.
homotopy digital topology fundamental group