منابع مشابه
Integral complete r-partite graphs
A graph is called integral if all the eigenvalues of its adjacency matrix are integers. In this paper, we give a useful sufficient and necessary condition for complete r-partite graphs to be integral, from which we can construct infinite many new classes of such integral graphs. It is proved that the problem of finding such integral graphs is equivalent to the problem of solving some Diophantin...
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We address the following problem: Given a complete k-partite geometric graph K whose vertex set is a set of n points in R, compute a spanner of K that has a “small” stretch factor and “few” edges. We present two algorithms for this problem. The first algorithm computes a (5 + )-spanner of K with O(n) edges in O(n log n) time. The second algorithm computes a (3 + )-spanner of K with O(n log n) e...
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Let A be a non-trivial Abelian group. We call a graph G = (V, E) A-magic if there exists a labeling f : E → A∗ such that the induced vertex set labeling f : V → A, defined by f(v) = ∑ uv∈E f(uv) is a constant map. In this paper, we show that Kk1,k2,...,kn (ki ≥ 2) is A-magic, for all A where |A| ≥ 3.
متن کاملThe Saturation Function of Complete Partite Graphs
A graph G is called F -saturated if it is F -free but the addition of any missing edge to G creates a copy of F . Let the saturation function sat(n, F ) be the minimum number of edges that an F -saturated graph on n vertices can have. We determine this function asymptotically for every fixed complete partite graph F as n tends to infinity and give some structural information about almost extrem...
متن کاملOn Chromatic Uniqueness of Complete Complete 6-Partite Graphs
Let P (G,λ) be the chromatic polynomial of a graph G. Two graphs G and H are said to be chromatically equivalent, denoted G ∼ H, if P (G,λ) = P (H,λ). We write [G] = {H|H ∼ G}. If [G] = {G}, then G is said to be chromatically unique. In this paper, we first characterize certain complete 6-partite graphs G with 6n + i vertices for i = 0, 1, 2 according to the number of 7-independent partitions o...
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 2002
ISSN: 0012-365X
DOI: 10.1016/s0012-365x(01)00269-2