We construct a new family (eta((q))(alpha))(alpha is an element of Comp) of quasisymmetric functions for each element q of the base ring. We call them the "enriched q-monomial quasisymmetric functions". When r := q + 1 is invertible, this family is a basis of QSym. It generalizes Hoffman's "essential quasi-symmetric functions" (obtained for q = 0) and Hsiao's "monomial peak functions" (obtained for q = 1), but also includes the monomial quasisymmetric functions as a limiting case. We describe these functions eta((q))(alpha) by several formulas, and compute their products, coproducts and antipodes. The product expansion is given by an exotic variant of the shuffle product which we call the "stufufuffle product" due to its ability to pick several consecutive entries from each composition. This "stufufuffle product" has previously appeared in recent work by Bouillot, Novelli and Thibon, generalizing the "block shuffle product" from the theory of multizeta values.
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Title
The enriched q-monomial basis of the quasisymmetric functions
Creators
Darij Grinberg - Drexel Univ, Dept Math, Philadelphia, PA 19104 USA
Ekaterina A. Vassilieva - Laboratoire Polytech'Lab
Publication Details
The Electronic journal of combinatorics, v 31(4), 12409
Publisher
Electronic Journal Of Combinatorics
Number of pages
65
Resource Type
Journal article
Language
English
Academic Unit
Mathematics
Web of Science ID
WOS:001337926600001
Scopus ID
2-s2.0-85208144656
Other Identifier
991021955314404721
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