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(n,e)-Graphs with maximum sum of squares of degrees*

โœ Scribed by Peled, Uri N.; Petreschi, Rossella; Sterbini, Andrea


Publisher
John Wiley and Sons
Year
1999
Tongue
English
Weight
308 KB
Volume
31
Category
Article
ISSN
0364-9024

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โœฆ Synopsis


Among all simple graphs on n vertices and e edges, which ones have the largest sum of squares of the vertex degrees? It is easy to see that they must be threshold graphs, but not every threshold graph is optimal in this sense. Boesch et al. [Boesch et al., Tech Rep, Stevens Inst Tech, Hoboken NJ, 1990] showed that for given n and e there exists exactly one graph of the form G 1 (p, q, r) = K p + (S q โˆช K 1,r ) and exactly one G 2 (p, q, r) = S p โˆช (K q + K 1,r ) and that one of them is optimal, where K and S indicate complete and edgeless graphs, K 1,r indicates a star on r + 1 vertices, โˆช indicates disjoint union, and + indicates complete disjoint join. We specify a general threshold graph in the form G * 1 (a, b, c, d, . . .


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