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EJC
2008
14 years 9 months ago
3-bounded property in a triangle-free distance-regular graph
Let denote a distance-regular graph with classical parameters (D, b, , ) and D 3. Assume the intersection numbers a1 = 0 and a2 = 0. We show is 3-bounded in the sense of the ar...
Yeh-jong Pan, Chih-wen Weng
EJC
2008
14 years 9 months ago
Identifying codes of cycles with odd orders
The problem of the r-identifying code of a cycle Cn has been solved totally when n is even. Recently, S. Gravier et al. give the r-identifying code for the cycle Cn with the minim...
Min Xu, Krishnaiyan Thulasiraman, Xiao-Dong Hu
EJC
2008
14 years 9 months ago
Graph parameters and semigroup functions
Abstract. We prove a general theorem on semigroup functions that implies characterizations of graph partition functions in terms of the positive semidefiniteness (`reflection posit...
László Lovász, Alexander Schr...
EJC
2008
14 years 9 months ago
On the number of combinations without certain separations
Abstract. In this paper we enumerate the number of ways of selecting k objects from n objects arrayed in a line such that no two selected ones are separated by m-1, 2m-1,
Toufik Mansour, Yidong Sun
EJC
2007
14 years 9 months ago
Hypertree width and related hypergraph invariants
We study the notion of hypertree width of hypergraphs. We prove that, up to a constant factor, hypertree width is the same as a number of other hypergraph invariants that resemble...
Isolde Adler, Georg Gottlob, Martin Grohe