Uld-lattices and Δ-bonds

  • Authors:
  • Stefan Felsner;Kolja b. Knauer

  • Affiliations:
  • Institut für mathematik, technische universität berlin, germany (e-mail: felsner@math.tu-berlin.de, knauer@math.tu-berlin.de);Institut für mathematik, technische universität berlin, germany (e-mail: felsner@math.tu-berlin.de, knauer@math.tu-berlin.de)

  • Venue:
  • Combinatorics, Probability and Computing
  • Year:
  • 2009

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Abstract

We provide a characterization of upper locally distributive lattices (ULD-lattices) in terms of edge colourings of their cover graphs. In many instances where a set of combinatorial objects carries the order structure of a lattice, this characterization yields a slick proof of distributivity or UL-distributivity. This is exemplified by proving a distributive lattice structure on Δ-bonds with invariant circular flow-difference. This instance generalizes several previously studied lattice structures, in particular, c-orientations (Propp), α-orientations of planar graphs (Felsner, resp. de Mendez) and planar flows (Khuller, Naor and Klein). The characterization also applies to other instances, e.g., to chip-firing games.