Figure 2
(a) An infinite chain graph with vertices of degree 1 and 3, in which repeat units are separated by dashed lines and edge 2–2 extends outside the repeat unit; (b) a finite wrapped graph in which edges that extend outside the repeat unit in (a) are wrapped to form a loop at vertex 2; (c) an infinite chain graph with vertices of degree 1, 2 and 3; (d) a finite wrapped graph in which edges that extend outside the repeat unit in (c) are wrapped to form a curved edge between vertices 1 and 2. Straight black arrows indicate the infinite extension of chain graphs in the +c and −c directions. Curved black arrows in (a) and (c) indicate how edges are wrapped in (b) and (d), and curved black lines represent wrapped edges in (b) and (d). Dashed black lines show the repeat units of each chain graph. |