Theorem 5.29: (1)IfG has a subgraph homeomorphic to Kn, then there exists at least n vertices with the degree more than or equal n (2)IfG has a subgraph homeomorphic to K then there exists at least 2n vertices with the degree more than or equal n. Example: Let G=(V,E), V=7. IfG has a subgraph homeomorphic to Ks, then G has not any subgraph homeomorphic to 3. 3 or▪ Theorem 5.29: (1)If G has a subgraph homeomorphic to Kn , then there exists at least n vertices with the degree more than or equal n-1. ▪ (2) If G has a subgraph homeomorphic to Kn,n, then there exists at least 2n vertices with the degree more than or equal n. ▪ Example: Let G=(V,E)，|V|=7. If G has a subgraph homeomorphic to K5 , then has not any subgraph homeomorphic to K3.3 or K5 . G