Partitioning multi-dimensional sets in a small number of "Uniform" parts

  • Authors:
  • Noga Alon;Ilan Newman;Alexander Shen;Gábor Tardos;Nikolai Vereshchagin

  • Affiliations:
  • Schools of Mathematics and Computer Science, Tel Aviv University, Tel Aviv, Israel and Institute for Advanced Study, Princeton, NJ;University of Haifa, Haifa, Israel;Institute for Information Transmission Problems, Russian Academy of Science, Poncelet Laboratory, Russian Federation;Rényi Institute, Budapest, Hungary;Moscow State University, Leninskie Gory, Moscow, Russian Federation and University of Provence

  • Venue:
  • European Journal of Combinatorics
  • Year:
  • 2007

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Abstract

Our main result implies the following easily formulated statement. The set of edges E of every finite bipartite graph can be split into poly(log |E|) subsets so that all the resulting bipartite graphs are almost regular. The latter means that the ratio between the maximal and minimal non-zero degree of the left nodes is bounded by a constant and the same condition holds for the right nodes. Stated differently, every finite 2-dimensional set S ⊂ N2 can be partitioned into poly(log |S|) parts so that in every part the ratio between the maximal size and the minimal size of non-empty horizontal section is bounded by a constant and the same condition holds for vertical sections. We prove a similar statement for n-dimensional sets for any n and show how it can be used to relate information inequalities for Shannon entropy of random variables to inequalities between sizes of sections and their projections of multi-dimensional finite sets.