Categories graded and bigraded by monoidal categories: functor categories and bifunctors over non-symmetric bases

Rory Lucyshyn-Wright

Brandon University




Abstract: Categories graded by a monoidal category V, or (V-)graded categories, were introduced by Richard Wood (who called them large V-categories), and they have appeared in work of several authors: Kelly, Labella, Schmitt, and Street (who called them procategories); Garner; Levy (who called them locally graded categories); McDermott and Uustalu. Graded categories generalize both V-enriched categories and V-actegories while demanding no assumptions on V. In this talk, we introduce (left) V-graded categories and their dual notions, namely right V-graded categories and V-cograded categories, as well as a notion of V-W-bigraded category for a pair of monoidal categories V and W. We discuss the speaker's recent results on functor categories and bifunctors for graded and bigraded categories. These results enable the consideration of graded functor categories and (bi)graded bifunctors for arbitrary monoidal categories. Contrastingly, the familiar methods of enriched category theory permit the consideration of enriched functor categories and bifunctors only when the base of enrichment is assumed symmetric, braided, or (more generally) normal duoidal in the sense of Garner and López-Franco.