DM
2016
8 years 26 days ago
2016
A set partition σ of [n] = {1, . . . , n} contains another set partition π if restricting σ to some S ⊆ [n] and then standardizing the result gives π. Otherwise we say σ av...
DM
2016
8 years 26 days ago
2016
A family A of sets is t-intersecting if the size of the intersection of every pair of sets in A is at least t, and it is an r-family if every set in A has size r. A wellknown theor...
DM
2016
8 years 26 days ago
2016
DM
2016
8 years 26 days ago
2016
DM
2016
8 years 26 days ago
2016
Abstract. We prove that the combinatorial optimization problem of determining the hull number of a partial cube is NP-complete. This makes partial cubes the minimal graph class for...
DM
2016
8 years 26 days ago
2016
We determine the structure of clonal classes of 3-connected frame matroids in terms of the structure of biased graphs. Robbins has conjectured that a 3-connected nonuniform matroid...
DM
2016
8 years 26 days ago
2016
For a k-uniform hypergraph G with vertex set {1, . . . , n}, the ordered Ramsey number ORt(G) is the least integer N such that every t-coloring of the edges of the complete k-unifo...
DM
2016
8 years 26 days ago
2016
Let G = (V, E) be a graph of order n. A distance magic labeling of G is a bijection ℓ: V → {1, 2, . . . , n} for which there exists a positive integer k such that ∑ x∈N(v)...
DM
2016
8 years 26 days ago
2016
A graph is called integral if all eigenvalues of its adjacency matrix consist entirely of integers. We prove that for a given nullity more than 1, there are only finitely many in...
DM
2016
8 years 26 days ago
2016
In this paper we present an explicit formula for the number of permutations with a given number of alternating descents. As an application, we obtain an interlacing property for th...