Manouchehr Zaker

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Given a graph G, by a Grundy k-coloring of G we mean any proper k-vertex coloring of G such that for each two colors i and j, i < j , every vertex ofG colored by j has a neighbor with color i. The maximum k for which there exists a Grundy k-coloring is denoted by (G) and called Grundy (chromatic) number of G. We first discuss the fixed-parameter complexity(More)
For a graph G and an order a on V(G), we define a greedy defining set as a subset S of V(G) with an assignment of colors to vertices in S, such that the pre-coloring can be extended to a x( G)-coloring of G by the greedy coloring of (G, a). A greedy defining set ofaX( G)-coloring C of G is a greedy defining set, which results in the coloring C (by the(More)
A defining set (of vertex coloring) of a graph G is a set of vertices S with an assignment of colors to its elements which has a unique completion to a proper coloring of G. We define a minimal defining set to be a defining set which does not properly contain another defining set. If G is a uniquely vertex colorable graph, clearly its minimum defining sets(More)
A Grundy k-coloring of a graph G, is a vertex k-coloring of G such that for each two colors i and j with i < j, every vertex of G colored by j has a neighbor with color i. The Grundy chromatic number Γ(G), is the largest integer k for which there exists a Grundy k-coloring for G. In this note we first give an interpretation of Γ(G) in terms of the total(More)
In a given graph G, a set of vertices S with an assignment of colors is said to be a defining set o f the vertex coloring o f G, if there exists a unique extension of the colors of S to a z(G)coloring of the vertices of G. The concept of a defining set has been studied, to some extent, for block designs and also under another name, a critical set, for latin(More)
Let G be a graph and τ : V (G) → N be an assignment of thresholds to the vertices ofG. A subset of verticesD is said to be dynamic monopoly (or simply dynamo) if the vertices of G can be partitioned into subsets D0,D1, . . . ,Dk such that D0 = D and for any i = 1, . . . , k − 1 each vertex v in Di+1 has at least t(v) neighbors in D0∪ . . .∪Di. Dynamic(More)
Let G be a graph and τ : V (G) → N ∪ {0} be an assignment of thresholds to the vertices of G. A subset of vertices D is said to be a dynamic monopoly corresponding to (G, τ) if the vertices of G can be partitioned into subsets D0,D1, . . . ,Dk such that D0 = D and for any i ∈ {0, . . . , k − 1}, each vertex v in Di+1 has at least τ(v) neighbors in D0 ∪ . .(More)