In this paper we present a self-contained combinatorial proof of the lower bound theorem for normal pseudomanifolds, including a treatment of the cases of equality in this theorem. We also discuss McMullen and Walkup’s generalised lower bound conjecture for triangulated spheres in the context of the lower bound theorem. Finally, we pose a new lower bound conjecture for non-simply connected tria...

In this lecture, we show two results dealing with lower bounds in communication complexity. The first lower bound is an Ω(n) lower bound on the distributional complexity of Disjointness due to [3, 8]. Here we will present the simplified proof presented in [8]. In the second part, we will show how to obtain lower bounds on the unbounded error probabilistic communication complexity by Forster’s m...

In this paper the following improvement on Freiman’s theorem on set addition is obtained. (Theorem 1 and Theorem 2 in Section 1.) Let A ⊂ Z be a finite set such that |A + A| < α|A|. Then A is contained in a proper d-dimensional progression P , where d ≤ [α− 1] and log |P | |A| < Cα2(log α)3. Earlier bounds involved exponential dependence in α in the second estimate. Our argument combines Ruzsa’...

Folkman’s theorem asserts that for each k ∈ N, there exists a natural number n = F (k) such that whenever the elements of [n] are two-coloured, there exists a set A ⊂ [n] of size k with the property that all the sums of the form ∑ x∈B x, where B is a nonempty subset of A, are contained in [n] and have the same colour. In 1989, Erdős and Spencer showed that F (k) ≥ 2ck2/ log , where c > 0 is an ...

R. P. Stanley proved the Upper Bound Conjecture in 1975. We imitate his proof for the Ehrhart rings. We give some upper bounds for the volume of integrally closed lattice polytopes. We derive some inequalities for the delta-vector of integrally closed lattice polytopes. Finally we apply our results for reflexive integrally closed and order polytopes.

Meshalkin’s theorem states that a class of ordered p-partitions of an n-set has at most max ( n a1,...,ap ) members if for each k the k parts form an antichain. We give a new proof of this and the corresponding LYM inequality due to Hochberg and Hirsch, which is simpler and more general than previous proofs. It extends to a common generalization of Meshalkin’s theorem and Erdős’s theorem about ...

In 2006, Smith et al. published a new table of constant weight codes, updating existing tables originally created by Brouwer et al. This paper improves upon these results by filling in 9 missing constant weight codes, all of which are optimal by the second Johnson bound. This completes the tables for A(n, 16, 9) and A(n, 18, 10) up to n = 63 and corrects some A(n, 14, 8).

This paper concerns versions of the Trotter-Kato Theorem and the Chernoff Product Formula for C0-semigroups in the absence of stability. Applications to A-stable rational approximations of semigroups are presented.

The theory of confinement and deconfinement is discussed as based on the properties of the QCD vacuum. The latter are described by field correlators of colour-electric and colour-magnetic fields in the vacuum, which can be calculated analytically and on the lattice. As a result one obtains a self-consistent theory of the confined region in the (µ, T) plane with realistic hadron properties. At t...