Integration of a categorical operad
Dominik Trnka
TL;DR
This paper develops an operadic Grothendieck construction for non-symmetric operads valued in Cat, producing a 2-category called IntP that is fibered over $Delta_s$. It proves an equivalence between constant-free non-symmetric categorical operads and split-fibered operadic 2-categories over $Delta_s$, with an inverse reconstruction from a split-fibered 2-category. The results unify operadic and order-theoretic structures (e.g., grafting and edge contractions on planar rooted trees) and connect to the classical presheaf/fibration correspondence in the discrete case. The framework sets the stage for generalizations to broader operadic categories and provides tools to combine operadic and poset structures in a coherent 2-categorical setting.
Abstract
We describe a Grothendieck construction for non-symmetric operads with values in categories, and hence in groupoids and posets. The construction produces a 2-category which is operadically fibered over the category D of finite non-empty ordinals and surjections. We describe an inverse for the construction, yielding an equivalence of constant-free non-symmetric categorical operads and operadic 2-categories (split-)fibered over D, which resembles the correspondence of categorical presheaves and fibered categories. The result provides a new characterization of non-symmetric categorical operads and tools to study them.
