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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）.

This paper deals with the problem of labeling the vertices, edges and faces of a plane graph in such a way that the label of a face and the labels of the vertices and edges surrounding that face add up to a weight of that face, and the weights of all s-sided faces constitute an arithmetic progression of difference d, for each s that appears in the graph. The paper examines the existence of such labelings for disjoint union of plane graphs.

This paper presents an algorithm to evaluate estimated and exact system reliabilities for a computer network in the cloud computing environment.From the quality of service（QOS） viewpoint,the computer network should be maintained when falling to a specific state such that it cannot afford enough capacity to satisfy demand.Moreover,the transmission time should be concerned as well.Thus,the data can be sent through several disjoint minimal paths simultaneously to shorten the transmission time.Under the maintenance budget B and time constraint T,we evaluate the system reliability that d units of data can be sent from the cloud to the client through multiple paths.Two procedures are integrated in the proposed algorithm-an estimation procedure for estimated system reliability and an adjusting procedure utilizing the branch-and-bound approach for exact system reliability.Subsequently,the estimated system reliability with lower bound and upper bound,and exact system reliability are computed by applying the recursive sum of disjoint products（RSDP） algorithm.

A proper vertex coloring of a graph G is linear if the graph induced by the vertices of any two color classes is the union of vertex-disjoint paths. The linear chromatic number lc（G） of the graph G is the smallest number of colors in a linear coloring of G. In this paper, it is proved that every planar graph G with girth g and maximum degree A has （1） lc（G） ≤ △ ＋ 21 if △ ≥ 9; （2） lc（G） ≤[△/2]＋ 7 if g≥5; （3） lc（G） ≤ [△/2]＋2ifg≥7and△ ≥7.

Suppose that G is a planar graph with maximum degree △. In this paper it is proved that G is total-（△ ＋ 2）-choosable if （1） △ ≥ 7 and G has no adjacent triangles （i.e., no two triangles are incident with a common edge）; or （2） △ ≥6 and G has no intersecting triangles （i.e., no two triangles are incident with a common vertex）; or （3） △ ≥ 5, G has no adjacent triangles and G has no k-cycles for some integer k ∈ {5, 6}.

A directed triple system of order v with index λ, briefly by DTS（v,λ）, is a pair （X, B） where X is a v-set and B is a collection of transitive triples （blocks） on X such that every ordered pair of X belongs to λ blocks of B. A simple DTS（v, λ） is a DTS（v, λ） without repeated blocks. A simple DTS（v, ）,） is called pure and denoted by PDTS（v, λ） if （x, y, z） ∈ B implies （z, y, x）, （z, x, y）, （y, x, z）, （y, z, x）, （x, z, y） B. A large set of disjoint PDTS（v, λ）, denoted by LPDTS（v, λ）, is a collection of 3（v - 2）/λ disjoint pure directed triple systems on X. In this paper, some results about the existence for LPDTS（v, λ） are presented. Especially, we determine the spectrum of LPDTS（v, 2）.