Abstract
The set of Dyck paths of length 2n inherits a lattice structure from a bijection with the set of noncrossing partitions with the usual partial order. In this paper, we study the joint distribution of two statistics for Dyck paths: area (the area under the path) and rank (the rank in the lattice). While area for Dyck paths has been studied, pairing it with this rank function seems new, and we get an interesting (q, t)-refinement of the Catalan numbers. We present two decompositions of the corresponding generating function: One refines an identity of Carlitz and Riordan; the other refines the notion of γ-nonnegativity, and is based on a decomposition of the lattice of noncrossing partitions due to Simion and Ullman. Further, Biane’s correspondence and a result of Stump allow us to conclude that the joint distribution of area and rank for Dyck paths equals the joint distribution of length and reflection length for the permutations lying below the n-cycle (12· · ·n) in the absolute order on the symmetric group.
Similar content being viewed by others
References
Andrews G.E.: An introduction to Ramanujan’s “lost" notebook. Amer. Math. Monthly 86(2), 89–108 (1979)
Andrews G.E.: The Theory of Partitions. Cambridge University Press, Cambridge (1998)
Armstrong, D.: Generalized noncrossing partitions and combinatorics of Coxeter groups. Mem. Amer. Math. Soc. 202(949) (2009)
Armstrong D., Stump C., Thomas H.: A uniform bijection between nonnesting and noncrossing partitions. Trans. Amer. Math. Soc. 365(8), 4121–4151 (2013)
Bandlow, J., Killpatrick, K.: An area-to-inv bijection between Dyck paths and 312- avoiding permutations. Electron. J. Combin. 8(1), #R40 (2001)
Biane P.: Some properties of crossings and partitions. Discrete Math. 175(1-3), 41–53 (1997)
Bilotta S. et al.: Catalan structures and catalan pairs. Theoret. Comput. Sci. 502(2), 239–248 (2013)
Brändén, P.: Sign-graded posets, unimodality of W-polynomials and the Charney-Davis conjecture. Electron. J. Combin. 11(2), #R9 (2004)
Brändén P., Claesson A., Steingrímsson E.: Catalan continued fractions and increasing subsequences in permutations. Discrete Math. 258(1-3), 275–287 (2002)
Carlitz, L.: Problem: q-analog of the lagrange expansion. In: Abstracts and Problems from the Conference on Eulerian Series and Applications. Pennsylvania State University, Pennsylvania (1974)
Carlitz L., Riordan J.: Two element lattice permutation numbers and their q-generalization. Duke Math. J. 31(3), 371–388 (1964)
Edelman P.H.: On inversions and cycles in permutations. European J. Combin. 8(3), 269–279 (1987)
Ferrari L., Pinzani R.: Lattices of lattice paths. J. Statist. Plann. Inference 135(1), 77–92 (2005)
Flajolet P.: Combinatorial aspects of continued fractions. Discrete Math. 32(2), 125–161 (1980)
Foata, D., Schützenberger, M.-P.: Théorie Géométrique des Polynômes Eulériens. Lecture Notes in Math., Vol. 138. Springer-Verlag, Berlin (1970)
Gal Ś.R.: Real root conjecture fails for five- and higher-dimensional spheres. Discrete Comput. Geom. 34(2), 269–284 (2005)
Haglund, J.: The q, t-Catalan Numbers and the Space of Diagonal Harmonics. Univ. Lecture Ser., Vol. 41. American Mathematical Society, Providence, RI (2008)
Hall, H.T.: Meanders in a cayley graph. arXiv:math/0606170v1 (2006)
Hersh, P.: Deformation of chains via a local symmetric group action. Electron. J. Combin. 6, #R27 (1999)
Nevo E., Petersen T.K.: On γ-vectors satisfying the Kruskal-Katona inequalities. Discrete Comput. Geom. 45(3), 503–521 (2011)
Nevo E., Petersen T.K., Tenner B.E.: The γ-vector of a barycentric subdivision. J. Combin. Theory Ser. A 118(4), 1364–1380 (2011)
Odlyzko A.M., Wilf H.S.: The editor’s corner: n coins in a fountain. Amer. Math. Monthly 95(9), 840–843 (1988)
Petersen T.K.: On the shard intersection order of a Coxeter group. SIAMJ. Discrete Math. 27(4), 1880–1912 (2013)
Petersen T.K.: The sorting index. Adv. Appl. Math. 47(3), 615–630 (2011)
Postnikov A., Reiner V., Williams L.: Faces of generalized permutohedra. Doc. Math. 13, 207–273 (2008)
Reiner V.: Non-crossing partitions for classical reflection groups. Discrete Math. 177(1-3), 195–222 (1997)
Sapounakis, A., Tasoulas, I., Tsikouras, P.: On the dominance partial ordering of Dyck paths. J. Integer Seq. 9(2), Article 06.2.5 (2006)
Shareshian J., Wachs M.L.: Eulerian quasisymmetric functions. Adv. Math. 225(6), 2921–2966 (2010)
Simion R., Ullman D.: On the structure of the lattice of noncrossing partitions. Discrete Math. 98(3), 193–206 (1991)
Stanley, R.P.: Enumerative Combinatorics, Vol. 2. Cambridge Stud. Adv. Math., Vol. 62. Cambridge University Press, Cambridge (1999)
Stembridge J.R.: Coxeter cones and their h-vectors. Adv. Math. 217(5), 1935–1961 (2008)
Stump C.: More bijective catalan combinatorics on permutations and on signed permutations. J. Combin. 4(4), 419–447 (2013)
Zeng, J.: An expansion formula for the inversions and excedances in the symmetric group. arXiv:1206.3510 (2012)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Blanco, S.A., Petersen, T.K. Counting Dyck Paths by Area and Rank. Ann. Comb. 18, 171–197 (2014). https://doi.org/10.1007/s00026-014-0218-9
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00026-014-0218-9