{ "id": "1902.02705", "version": "v1", "published": "2019-02-07T16:09:38.000Z", "updated": "2019-02-07T16:09:38.000Z", "title": "Combinatorial specifications for juxtapositions of permutation classes", "authors": [ "Robert Brignall", "Jakub Sliacan" ], "comment": "22 pages, 6 figures", "categories": [ "math.CO" ], "abstract": "We show that, given a suitable combinatorial specification for a permutation class $\\mathcal{C}$, one can obtain a specification for the juxtaposition (on either side) of $\\mathcal{C}$ with Av(21) or Av(12), and that if the enumeration for $\\mathcal{C}$ is given by a rational or algebraic generating function, so is the enumeration for the juxtaposition. Furthermore this process can be iterated, thereby providing an effective method to enumerate any 'skinny' $k\\times 1$ grid class in which at most one cell is non-monotone, with a guarantee on the nature of the enumeration given the nature of the enumeration of the non-monotone cell.", "revisions": [ { "version": "v1", "updated": "2019-02-07T16:09:38.000Z" } ], "analyses": { "keywords": [ "permutation class", "juxtaposition", "enumeration", "suitable combinatorial specification", "grid class" ], "note": { "typesetting": "TeX", "pages": 22, "language": "en", "license": "arXiv", "status": "editable" } } }