Acta mathematica scientia,Series A ›› 1999, Vol. 19 ›› Issue (5): 481-485.

• Articles •     Next Articles

Neighborhood Unions and [a,b] Factors

  

  1. (Department of Basic Courses, Shandong Agricultural University, Taian 271018)

  • Online:1999-12-05 Published:1999-12-05

Abstract:

Let a≤b be integers and G a graph. A spanning subgraph F of G is called an [a,b] factor of G if a≤dF(v)≤b for all v∈V(G). A sufficient condition concerning neighborhood unions for the existence of an [a,b] factor in a graph is given. The author prove the following result: Let a(a+b)(2a+2b-3)/b. Assume |NG (u)∪NG (v)|≥an/(a+b), for each pair of nonadjacent vertices u,v in G and the minimum degree is at least a, Then G has an [a,b] factor.

Key words: Graph, [a,b]-factor, Neighborhoodunion.

CLC Number: 

  •  05C70
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