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Let $C$ be a category with finite colimits, writing its coproduct +, and let $(D, \otimes)$ be a braided monoidal category. We describe a method of producing a symmetric monoidal category from a lax braided monoidal functor $F : (C,+) \to (D, \otimes)$, and of producing a strong monoidal functor between such categories from a monoidal natural transformation between such functors. The objects of these categories, our so-called `decorated cospan categories', are simply the objects of $C$, while the morphisms are pairs comprising a cospan $X \rightarrow N \leftarrow Y$ in $C$ together with an element $1 \to FN$ in $D$. Moreover, decorated cospan categories are hypergraph categories - each object is equipped with a special commutative Frobenius monoid - and their functors preserve this structure.
@article{TAC_2015_30_a32, author = {Brendan Fong}, title = {Decorated cospans}, journal = {Theory and applications of categories}, pages = {1096--1120}, publisher = {mathdoc}, volume = {30}, year = {2015}, language = {en}, url = {http://geodesic.mathdoc.fr/item/TAC_2015_30_a32/} }
Brendan Fong. Decorated cospans. Theory and applications of categories, Tome 30 (2015), pp. 1096-1120. http://geodesic.mathdoc.fr/item/TAC_2015_30_a32/