CARMA-GTA DISCRETE MATHEMATICS SEMINAR Speaker: Dr Uwe Leck, Department of Mathematics and Computer Science, University of Wisconsin-Superior Title: Orthogonal Double Covers of Graphs Location: Room V129, Mathematics Building (Callaghan Campus) The University of Newcastle Time and Date: 4:00 pm, Tue, 28th Jun 2011 Abstract: The concept of orthogonal double covers (ODC) of graphs originates in questions concerning database constraints and problems in statistical combinatorics and in design theory. An ODC of the complete graph $K_n$ by a graph $G$ is a collection of $n$ subgraphs of $K_n$, all isomorphic to $G$, such that any two of them share exactly one edge, and every edge of $K_n$ occurs in exactly two of the subgraphs. We survey some of the main results and conjectures in the area as well as constructions, generalizations and modifications of ODC. [Permanent link]