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small graphs with exactly two nonnegative eigenvalues
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نویسنده
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derikvand tajedin ,oboudi mohammad reza
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منبع
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journal of algebraic structures and their applications - 2017 - دوره : 4 - شماره : 1 - صفحه:1 -18
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چکیده
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Let g be a graph with eigenvalues λ1(g) ≥ · · · ≥ λn(g). in this paper we find all simple graphs g such that g has at most twelve vertices and g has exactly two non-negative eigenvalues. in other words we find all graphs g on n vertices such that n ≤ 12 and λ1(g) ≥ 0, λ2(g) ≥ 0 and λ3(g) < 0. we obtain that there are exactly 1575 connected graphs g on n ≤ 12 vertices with λ1(g) > 0, λ2(g) > 0 and λ3(g) < 0. we find that among these 1575 graphs there are just two integral graphs.
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کلیدواژه
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spectrum of graphs ,eigenvalues of graphs ,graphs with exactly two nonnegative eigenvalues
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آدرس
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islamic azad university, marvdasht branch, department of mathematics, ایران, shiraz university, college of sciences, department of mathematics, ایران
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پست الکترونیکی
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mr oboudi@yahoo.com , mr oboudi@shirazu.ac.ir
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Authors
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