{ "id": "1107.5070", "version": "v2", "published": "2011-07-25T20:31:55.000Z", "updated": "2012-01-31T20:06:36.000Z", "title": "The Möbius function of generalized subword order", "authors": [ "Peter R. W. McNamara", "Bruce E. Sagan" ], "comment": "29 pages, 4 figures. Incorporates referees' suggestions; to appear in Advances in Mathematics", "journal": "Advances in Mathematics, 229 (5) (2012), 2741-2766", "categories": [ "math.CO", "math.AT" ], "abstract": "Let P be a poset and let P* be the set of all finite length words over P. Generalized subword order is the partial order on P* obtained by letting u \\leq w if and only if there is a subword u' of w having the same length as u such that each element of u is less than or equal to the corresponding element of u' in the partial order on P. Classical subword order arises when P is an antichain, while letting P be a chain gives an order on compositions. For any finite poset P, we give a simple formula for the Mobius function of P* in terms of the Mobius function of P. This permits us to rederive in a easy and uniform manner previous results of Bjorner, Sagan and Vatter, and Tomie. We are also able to determine the homotopy type of all intervals in P* for any finite P of rank at most 1.", "revisions": [ { "version": "v2", "updated": "2012-01-31T20:06:36.000Z" } ], "analyses": { "subjects": [ "06A07", "05A05", "55P15", "68R15" ], "keywords": [ "generalized subword order", "möbius function", "partial order", "mobius function", "finite length words" ], "tags": [ "journal article" ], "publication": { "publisher": "Elsevier", "journal": "Adv. Math." }, "note": { "typesetting": "TeX", "pages": 29, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2011arXiv1107.5070M" } } }