Abstract

We consider hexagonal systems embedded into the 3-dimensional space 3. We define the fundamental group π1(G) of such a system G and show that in case G is a finite hexagonal system with boundary, then π1(G) is a (non-Abelian) free group. In this case, the rank of π1(G) equals m(G)h(G)n(G)+1, where n(G) (resp., m(G), h(G)) denotes the number of vertices (resp., edges, hexagons) in G.