Parking spaces

Drew Armstrong, Victor Reiner, Brendon Rhoades

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Let W be a Weyl group with root lattice Q and Coxeter number h. The elements of the finite torus Q/(h+1)Q are called the W-parking functions, and we call the permutation representation of W on the set of W-parking functions the (standard) W-parking space. Parking spaces have interesting connections to enumerative combinatorics, diagonal harmonics, and rational Cherednik algebras. In this paper we define two new W-parking spaces, called the noncrossing parking space and the algebraic parking space, with the following features:•They are defined more generally for real reflection groups.•They carry not just W-actions, but W×C-actions, where C is the cyclic subgroup of W generated by a Coxeter element.•In the crystallographic case, both are isomorphic to the standard W-parking space. Our Main Conjecture is that the two new parking spaces are isomorphic to each other as permutation representations of W×C. This conjecture ties together several threads in the Catalan combinatorics of finite reflection groups. Even the weakest form of the Main Conjecture has interesting combinatorial consequences, and this weak form is proven in all types except E7 and E8. We provide evidence for the stronger forms of the conjecture, including proofs in some cases, and suggest further directions for the theory.

Original languageEnglish (US)
Pages (from-to)647-706
Number of pages60
JournalAdvances in Mathematics
StatePublished - Jan 1 2015


  • Absolute order
  • Catalan
  • Coxeter group
  • Cyclic sieving
  • Kirkman
  • Narayana
  • Noncrossing
  • Nonnesting
  • Parking function
  • Rational cherednik algebra
  • Reflection group

ASJC Scopus subject areas

  • Mathematics(all)


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