We prove that if s and t are positive integers and if G is a triangle-free graph with minimum degree s + t, then the vertex set of G has a decomposition into two sets which induce subgraphs of minimum degree at least s and t, respectively.
Decomposition of bipartite graphs under degree constraints
β Scribed by H. J. Broersma; R. J. Faudree; J. Den Van Heuvel; H. J. Veldman
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 339 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0028-3045
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β¦ Synopsis
Abstract
Let G = (A, B; E) be a bipartite graph. Let e~1~, e~2~ be nonnegative integers, and f~1~, f~2~ nonnegative integerβvalued functions on V(G) such that e~i~ β¦ |E| β¦ e~1~ + e~2~ and f~i~(v) β¦ d(v) β¦ f~1~(v) + f~2~(v) for all v Ο΅ V(G) (i = 1, 2). Necessary and sufficient conditions are obtained for G to admit a decomposition in spanning subgraphs G~1~ = (A, B; E~1~) and G~2~ = (A, B; E~2~) such that |E~i~| β¦ e~i~ and d~Gi~(v) β¦ f~i~(v) for all v Ο΅ V(G) (i = 1, 2). The result generalizes a known characterization of bipartite graphs with a kβfactor. Its proof uses flow theory and is a refinement of the proof of an analogous result due to Folkman and Fulkerson. By applying corresponding flow algorithms, the described decomposition can be found in polynomial time if it exists. As an application, an assignment problem is solved. Β© 1993 by John Wiley & Sons, Inc.
π SIMILAR VOLUMES
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