A bijective proof of Jackson's formula for the number of factorizations of a cycle

  • Authors:
  • Gilles Schaeffer;Ekaterina Vassilieva

  • Affiliations:
  • LIX, Laboratoire d'Informatique de l'École Polytechnique, 91128 Palaiseau Cedex, France;LIX, Laboratoire d'Informatique de l'École Polytechnique, 91128 Palaiseau Cedex, France

  • Venue:
  • Journal of Combinatorial Theory Series A
  • Year:
  • 2008

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Abstract

Factorizations of the cyclic permutation (12...N) into two permutations with respectively n and m cycles, or, equivalently, unicellular bicolored maps with N edges and n white and m black vertices, have been enumerated independantly by Jackson and Adrianov using evaluations of characters of the symmetric group. In this paper we present a bijection between unicellular partitioned bicolored maps and couples made of an ordered bicolored tree and a partial permutation, that allows for a combinatorial derivation of these results. Our work is closely related to a recent construction of Goulden and Nica for the celebrated Harer-Zagier formula, and indeed we provide a unified presentation of both bijections in terms of Eulerian tours in graphs.