Basic analytic combinatorics of directed lattice paths

  • Authors:
  • Cyril Banderier;Philippe Flajolet

  • Affiliations:
  • Algorithms Project, Le Chesnay, France;-

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2002

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Abstract

This paper develops a unified enumerative and asymptotic theory of directed two-dimensional lattice paths in half-planes and quarter-planes. The lattice paths are specified by a finite set of rules that are both time and space homogeneous, and have a privileged direction of increase. (They are then essentially one-dimensional objects.) The theory relies on a specific "kernel method" that provides an important decomposition of the algebraic generating functions involved, as well as on a generic study of singularities of an associated algebraic curve. Consequences are precise computable estimates for the number of lattice paths of a given length under various constraints (bridges, excursions, meanders) as well as a characterization of the limit laws associated to several basic parameters of paths.