The graph product denoted 
and defined by the adjacency relations (
) or (
and 
). The graph lexicographic product is also known as the
graph composition (Harary 1994, p. 21).
Graph lexicographic products can be computed in the Wolfram Language using GraphProduct[G1, G2, "Lexicographic"].
The "double graph" of a given graph 
is the graph lexicographic product 
.
