Combinatorial & Computational Properties of the Hypercube - New Results on Covering, Slicing, Clustering and Searching on the Hypercube

O. Aichholzer

Abstract:

The central topic of this thesis is the $d$-dimensional hypercube ($d$-cube). Despite of its simple definition, the $d$-cube has been an object of study from various points of view. The contributions of this thesis are twofold. In the combinatorial part we investigate the structure of hyperplanes intersecting the $d$-cube: How many and which types of hyperplanes can be spanned by vertices of the $d$-cube? What is the minimum number of skew hyperplanes that cover all the vertices of the $d$-cube? What is the best arrangement of slicing hyperplanes to linearly separate all neighbours on the $d$-cube? Such results are then used e.g. for determining the maximal number of facets a 5-dimensional $0/1$-polytope can achieve. In the second part of the thesis we consider algorithmical properties of the $d$-cube. We first obtain efficient clustering methods for objects represented as binary strings of fixed length $d$, including various agglomerative hierarchical methods like single linkage and complete linkage. Utilizing these hierarchical structures we derive a new efficient approach to the ${0,1}$-string searching problem, where for a given set of binary strings of fixed length $d$ and a query string one asks for the most similar string in this set. Motivation for investigating these problems stems, among other areas, from coding theory, communication theory, and learning theory.



Reference: O. Aichholzer. Combinatorial & Computational Properties of the Hypercube - New Results on Covering, Slicing, Clustering and Searching on the Hypercube. PhD thesis, IGI-TU Graz, Austria, 1997.

www-data, 2020-09-10