disjoint union of graphs

The union G = G_1 union G_2 of graphs G_1 and G_2 with disjoint point sets V_1 and V_2 and edge sets X_1 and X_2 is the graph with V = V_1 union V_2 and X = X_1 union X_2. When the vertices and edges of G_1 and G_2 are considered distinct regardless of their labels, the operation is sometimes known as the graph disjoint union in order to distinguish it from the graph union operation that merges vertices and edges with shared labels when taking the unions of edges and vertices in G_1 and G_2.

graph intersection | graph join | graph sum