In [2] the k-line graph Lk (G) of a graph G of size m¿1, where 16k6m, is dened
as that graph whose vertices are the
edge-induced subgraphs of size k in G, and
where vertices F and H are adjacent in Lk (G) if and only if dr(F; H) = 1. Hence
L1(G) is the line graph L(G). The k-line graph is also referred to as the k-rotation
graph. We label each vertex of Lk (G) by listing the edges of the respective subgraph;
each edge in the label is called a coordinate. For a vertex {e1; e2;:::;ek} of Lk (G),
we write e1e2 ··· ek or, at times, etX , where X = {ei | i = 1; 2;:::;k; i 6= t}. If k = 1,
then etX = et.