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We introduce a general notion of enrichment for homotopy-coherent algebraic structures described by Segal conditions, using the framework of "algebraic patterns" developed in our previous work. This recovers several known examples of…

Category Theory · Mathematics 2023-11-22 Hongyi Chu , Rune Haugseng

It was shown in a recent paper by Boavida de Brito and Weiss that a well-known construction which to a plain (=monochromatic) topological operad associates a topological category and a functor from it to the category of finite sets is…

Algebraic Topology · Mathematics 2018-03-28 Michael S. Weiss

We compare two approaches to the homotopy theory of infinity-operads. One of them, the theory of dendroidal sets, is based on an extension of the theory of simplicial sets and infinity-categories which replaces simplices by trees. The other…

Algebraic Topology · Mathematics 2015-01-30 Gijs Heuts , Vladimir Hinich , Ieke Moerdijk

We show that every action operad gives rise to a notion of monoidal category via the categorical version of the Borel construction, embedding action operads into the category of 2-monads on $\mathbf{Cat}$. We characterize those 2-monads in…

Category Theory · Mathematics 2015-08-18 Nick Gurski

In a first part of this paper, we introduce a homology theory for infinity-operads and for dendroidal spaces which extends the usual homology of differential graded operads defined in terms of the bar construction, and we prove some of its…

Category Theory · Mathematics 2021-05-26 Eric Hoffbeck , Ieke Moerdijk

We define an action of the operad of projective spineless cacti on each stage of the Taylor tower for the space of framed 1-dimensional long knots in any Euclidean space. By mapping a subspace of the overlapping intervals operad to the…

Algebraic Topology · Mathematics 2025-09-09 Robin Koytcheff , Yongheng Zhang

We introduce a new model structure on the category of dendroidal spaces, designed to provide a further model for the homotopy theory of $\infty$-operads. This model is directly analogous to a recent construction on the category of…

Algebraic Topology · Mathematics 2026-01-15 João Candeias , Javier J. Gutiérrez

We compare two models for $\infty$-operads: the complete Segal operads of Barwick and the complete dendroidal Segal spaces of Cisinski and Moerdijk. Combining this with comparison results already in the literature, this implies that all…

Algebraic Topology · Mathematics 2020-11-03 Hongyi Chu , Rune Haugseng , Gijs Heuts

We introduce the analogues of the notions of complete Segal space and of Segal category in the context of equivariant operads with norm maps, and build model categories with these as the fibrant objects. We then show that these model…

Algebraic Topology · Mathematics 2021-06-09 Peter Bonventre , Luis Alexandre Pereira

We develop an alternative to the May-Thomason construction used to compare operad based infinite loop machines to that of Segal, which relies on weak products. Our construction has the advantage that it can be carried out in $Cat$, whereas…

Algebraic Topology · Mathematics 2016-05-04 Zbigniew Fiedorowicz , Manfred Stelzer , Rainer M. Vogt

Modular operads are an extension of operads. In the same way that operads, as dendroidal sets, can be considered as presheaves over the category of trees, so can modular operads be considered as presheaves over a category of graphs. This…

Category Theory · Mathematics 2025-04-10 Michelle Strumila

We develop a notion of an algebra over an infinity-operad with values in infinity-categories which is completely intrinsic to the formalism of dendroidal sets. Its definition involves the notion of a coCartesian fibration of dendroidal sets…

Algebraic Topology · Mathematics 2011-12-06 Gijs Heuts

We endow categories of non-symmetric operads with natural model structures. We work with no restriction on our operads and only assume the usual hypotheses for model categories with a symmetric monoidal structure. We also study categories…

Algebraic Topology · Mathematics 2011-05-31 Fernando Muro

This monograph provides a coherent development of operads, infinity operads, and monoidal categories, equipped with equivariant structures encoded by an action operad. A group operad is a planar operad with an action operad equivariant…

Category Theory · Mathematics 2022-03-08 Donald Yau

We give a definition of an operad with general groups of equivariance suitable for use in any symmetric monoidal category with appropriate colimits. We then apply this notion to study the 2-category of algebras over an operad in Cat. We…

Category Theory · Mathematics 2014-02-28 Alexander S. Corner , Nick Gurski

We prove that the category of trees $\Omega$ is a test category in the sense of Grothendieck. This implies that the category of dendroidal sets is endowed with the structure of a model category Quillen-equivalent to spaces. We show that…

Algebraic Topology · Mathematics 2020-09-09 Dimitri Ara , Denis-Charles Cisinski , Ieke Moerdijk

Let $\mathbb{E}_d$ denote the little discs operad for $1 \le d \le \infty$ and let $\mathcal{C}$ be an $\infty$-category all of whose mapping spaces are $n$-truncated. We prove that when considering $\mathbb{E}_d$-monoids in $\mathcal{C}$,…

Algebraic Topology · Mathematics 2023-04-26 Shaul Barkan

We introduce an operad of formal fractions, abstracted from the Mould operads and containing both the Dendriform and the Tridendriform operads. We consider the smallest set-operad contained in this operad and containing four specific…

Combinatorics · Mathematics 2013-07-02 Frédéric Chapoton , Florent Hivert , Jean-Christophe Novelli

This note is an introduction to several generalizations of the dendroidal sets of Moerdijk--Weiss. Dendroidal sets are presheaves on a category of rooted trees, and here we consider indexing categories whose objects are other kinds of…

Category Theory · Mathematics 2025-03-10 Philip Hackney

We show that various categories of trees can be modeled by Grothendieck constructions on categories of trees with a fixed set of leaves. We prove this result for the dendroidal category $\Omega$, the category $\Omega^G$ of trees with a…

Algebraic Topology · Mathematics 2026-03-06 Julia E. Bergner , Maxine E. Calle , David Chan , Angélica M. Osorno , Maru Sarazola