Research on the Non-Planarity about the Tensor Product of Graphs

Abstract

The main purpose of this paper is to study the non-planarity of a graph after the tensor product operation. Introduced the concept of invariant property of graphs concerning some operations. Proved the non-planarity of the graph K3,3 and graph K5 is preserved after the bipartite double cover operation. The main conclusion is that the non-planarity of a graph is a invariant property belonging to the bipartite double cover operation, and hence proved the non-planarity of a graph is preserved after the tensor product operation, and conversely, the planarity of a graph is not preserved after the tensor product operation.