Counterpart results in word spaces

In this paper after algebraical and geometrical preliminaries we present a Gram-Schmidt-type algorithmical conjecture, which if true settles the long-standing Hadamard conjecture concerning the existence of orthogonal matrices with elements of the same absolute value. Citation Unpublished, ELTE Operation Research Report 2015/1 Article Download View Counterpart results in word spaces

Bounds on the stability number of a graph via the inverse theta function

In the paper we consider degree, spectral, and semide finite bounds on the stability number of a graph. The bounds are obtained via reformulations and variants of the inverse theta function, a notion recently introduced by the author in a previous work. Article Download View Bounds on the stability number of a graph via the inverse … Read more

Multiplically independent word systems

Tressler’s Theorem states that the long-standing Hadamard conjecture (concerning the existence of n by n orthogonal matrices with elements of the same absolute value, for n=4k, k=1,2,…) will be settled if we find n-2 pairwise orthogonal words in a hyperplane of words. In this paper we will prove the counterpart of Tressler’s Theorem: the existence … Read more

On closedness conditions, strong separation, and convex dualit y

In the paper, we describe various applications of the closedness and duality theorems of [7] and [8]. First, the strong separability of a polyhedron and a linear image of a convex set is characterized. Then,it is shown how stability conditions (known from the generalized Fenchel-Rockafellar duality theory) can be reformulated as closedness conditions. Finally, we … Read more

Simplex-type algorithm for optimizing a pseudolinear quadratic fractional function over a polytope

Recently Cambini and Carosi described a characterization of pseudolinearity of quadratic fractional functions. A reformulation of their result was given by Rapcsák. Using this reformulation, in this paper we describe an alternative proof of the Cambini–Carosi Theorem. Our proof is shorter than the proof given by Cambini–Carosi and less involved than the proof given by … Read more