Star-Cycle Factors of Graphs

Yoshimi Egawa; Mikio Kano; Zheng Yan

Discussiones Mathematicae Graph Theory (2014)

  • Volume: 34, Issue: 1, page 193-198
  • ISSN: 2083-5892

Abstract

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A spanning subgraph F of a graph G is called a star-cycle factor of G if each component of F is a star or cycle. Let G be a graph and f : V (G) → {1, 2, 3, . . .} be a function. Let W = {v ∈ V (G) : f(v) = 1}. Under this notation, it was proved by Berge and Las Vergnas that G has a star-cycle factor F with the property that (i) if a component D of F is a star with center v, then degF (v) ≤ f(v), and (ii) if a component D of F is a cycle, then V (D) ⊆ W if and only if iso(G − S) ≤ Σx∈S f(x) for all S ⊂ V (G), where iso(G − S) denotes the number of isolated vertices of G − S. They proved this result by using circulation theory of flows and fractional factors of graphs. In this paper, we give an elementary and short proof of this theorem.

How to cite

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Yoshimi Egawa, Mikio Kano, and Zheng Yan. "Star-Cycle Factors of Graphs." Discussiones Mathematicae Graph Theory 34.1 (2014): 193-198. <http://eudml.org/doc/267810>.

@article{YoshimiEgawa2014,
abstract = {A spanning subgraph F of a graph G is called a star-cycle factor of G if each component of F is a star or cycle. Let G be a graph and f : V (G) → \{1, 2, 3, . . .\} be a function. Let W = \{v ∈ V (G) : f(v) = 1\}. Under this notation, it was proved by Berge and Las Vergnas that G has a star-cycle factor F with the property that (i) if a component D of F is a star with center v, then degF (v) ≤ f(v), and (ii) if a component D of F is a cycle, then V (D) ⊆ W if and only if iso(G − S) ≤ Σx∈S f(x) for all S ⊂ V (G), where iso(G − S) denotes the number of isolated vertices of G − S. They proved this result by using circulation theory of flows and fractional factors of graphs. In this paper, we give an elementary and short proof of this theorem.},
author = {Yoshimi Egawa, Mikio Kano, Zheng Yan},
journal = {Discussiones Mathematicae Graph Theory},
keywords = {star factor; cycle factor; star-cycle factor; factor of graph},
language = {eng},
number = {1},
pages = {193-198},
title = {Star-Cycle Factors of Graphs},
url = {http://eudml.org/doc/267810},
volume = {34},
year = {2014},
}

TY - JOUR
AU - Yoshimi Egawa
AU - Mikio Kano
AU - Zheng Yan
TI - Star-Cycle Factors of Graphs
JO - Discussiones Mathematicae Graph Theory
PY - 2014
VL - 34
IS - 1
SP - 193
EP - 198
AB - A spanning subgraph F of a graph G is called a star-cycle factor of G if each component of F is a star or cycle. Let G be a graph and f : V (G) → {1, 2, 3, . . .} be a function. Let W = {v ∈ V (G) : f(v) = 1}. Under this notation, it was proved by Berge and Las Vergnas that G has a star-cycle factor F with the property that (i) if a component D of F is a star with center v, then degF (v) ≤ f(v), and (ii) if a component D of F is a cycle, then V (D) ⊆ W if and only if iso(G − S) ≤ Σx∈S f(x) for all S ⊂ V (G), where iso(G − S) denotes the number of isolated vertices of G − S. They proved this result by using circulation theory of flows and fractional factors of graphs. In this paper, we give an elementary and short proof of this theorem.
LA - eng
KW - star factor; cycle factor; star-cycle factor; factor of graph
UR - http://eudml.org/doc/267810
ER -

References

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  1. [1] J. Akiyama and M. Kano, Factors and Factorizations of Graphs (Lecture Notes in Math. 2031, Springer, 2011). Zbl1229.05001
  2. [2] A. Amahashi and M. Kano, On factors with given components, Discrete Math. 42 (1983) 1-6. doi:10.1016/0012-365X(82)90048-6[Crossref] Zbl0525.05048
  3. [3] C. Berge and M. Las Vergnas, On the existence of subgraphs with degree constraints, Nederl. Akad. Wetensch. Indag. Math. 40 (1978) 165-176. doi:10.1016/1385-7258(78)90034-3[Crossref] 
  4. [4] M. Las Vergnas, An extension of Tutte‘s 1-factor theorem, Discrete Math. 23 (1978) 241-255. doi:10.1016/0012-365X(78)90006-7[Crossref] 
  5. [5] W.T. Tutte, The 1-factors of oriented graphs, Proc. Amer. Math. Soc. 4 (1953) 922-931. doi:10.2307/2031831[Crossref] 

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