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EJC
2008
8 years 1 months ago
Constructive characterizations of 3-connected matroids of path width three
A matroid M is sequential or has path width 3 if M is 3-connected and its ground set has a sequential ordering, that is, an ordering (e1, e2, . . . , en) such that ({e1, e2, . . . ...
Brian Beavers, James Oxley
EJC
2008
8 years 1 months ago
On a class of finite symmetric graphs
Let be a G-symmetric graph, and let B be a nontrivial G-invariant partition of the vertex set of . This paper aims to characterize (, G) under the conditions that the quotient gr...
Sanming Zhou
EJC
2008
8 years 1 months ago
Locating sensors in paths and cycles: The case of 2-identifying codes
For a graph G and a set D V (G), define Nr[x] = {xi V (G) : d(x, xi) r} (where d(x, y) is graph theoretic distance) and Dr(x) = Nr[x] D. D is known as an r-identifying code if...
David L. Roberts, Fred S. Roberts
EJC
2008
8 years 3 months ago
Compatible decompositions and block realizations of finite metrics
Andreas W. M. Dress, Katharina T. Huber, Jacobus H...
EJC
2008
8 years 3 months ago
Partial ovoids and partial spreads in symplectic and orthogonal polar spaces
We present improved lower bounds on the sizes of small maximal partial ovoids and small maximal partial spreads in the classical symplectic and orthogonal polar spaces, and improv...
Jan De Beule, Andreas Klein, Klaus Metsch, Leo Sto...
EJC
2008
8 years 3 months ago
Majority constraints have bounded pathwidth duality
We study certain constraint satisfaction problems which are the problems of deciding whether there exists a homomorphism from a given relational structure to a fixed structure with...
Víctor Dalmau, Andrei A. Krokhin
EJC
2008
8 years 3 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
2008
8 years 3 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...
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