Let k be an integer with k ≥ 2 and G a graph with order n 〉 4k. We prove that if the minimum degree sum of any two nonadjacent vertices is at least n ＋ k, then G contains a vertex cover with exactly k components such that k - 1 of them are chorded 4-cycles. The degree condition is sharp in general.
A graph is said to be K1,4-free if it does not contain an induced subgraph isomorphic to K1,4. Let κ be an integer with κ ≥ 2. We prove that if G is a K1,4-free graph of order at least llκ- 10 with minimum degree at least four, then G contains k vertex-disjoint copies of K1 ＋ （K1 ∪ KK2）.
A graph is said to be claw-free if it does not contain an induced subgraph isomorphic to K1,3. Let K4 be the graph obtained by removing exactly one edge from K4 and let k be an integer with k ≥ 2. We prove that if G is a claw-free graph of order at least 13k - 12 and with minimum degree at least five, then G contains k vertex-disjoint copies of K4. The requirement of number five is necessary.
