EJC
2006
13 years 11 months ago
2006
A tube (resp. an oval tube) in PG(3, q) is a pair T = {L, L}, where {L} L is a collection of mutually disjoint lines of PG(3, q) such that for each plane of PG(3, q) containing L...
EJC
2006
13 years 11 months ago
2006
EJC
2006
13 years 11 months ago
2006
We study the positive Bergman complex B+ (M) of an oriented matroid M, which is a certain subcomplex of the Bergman complex B(M) of the underlying unoriented matroid M. The positiv...
EJC
2006
13 years 11 months ago
2006
In this paper we study the sequence (ci)0id for a distance-regular graph. In particular we show that if d 2j and cj = c > 1 then c2j > c holds. Using this we give improveme...
EJC
2008
13 years 11 months ago
2008
EJC
2008
13 years 11 months ago
2008
EJC
2008
13 years 11 months ago
2008
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...
EJC
2008
13 years 11 months ago
2008
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...
EJC
2008
13 years 11 months ago
2008
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,
EJC
2008
13 years 11 months ago
2008
Abstract. We prove a general theorem on semigroup functions that implies characterizations of graph partition functions in terms of the positive semidefiniteness (`reflection posit...