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We show that morphisms from n A_infinity-algebras to a single one are maps over an operad module with n+1 commuting actions of the operad A_infinity, whose algebras are conventional A_infinity-algebras. Similar statement holds for homotopy…

Category Theory · Mathematics 2015-11-30 Volodymyr Lyubashenko

Antiunitary representations of Lie groups take values in the group of unitary and antiunitary operators on a Hilbert space H. In quantum physics, antiunitary operators implement time inversion or a PCT symmetry, and in the modular theory of…

Representation Theory · Mathematics 2017-04-06 Karl-Hermann Neeb , Gestur Olafsson

This paper explores operators with countable, continuous, and hybrid spectra, focusing on both finite dimensional and infinite dimensional cases, particularly in non-Hermitian systems. For finite dimensional operators, a novel concept of…

Functional Analysis · Mathematics 2024-11-20 Shih-Yu Chang

We obtain an equivariant index theorem, or Lefschetz fixed-point formula, for isometries from complete Riemannian manifolds to themselves. The fixed-point set of such an isometry may be noncompact. We build on techniques developed by Roe.…

Differential Geometry · Mathematics 2024-01-10 Peter Hochs

We define a generalization of (coloured) operads based on double lax functors and we construct a model structure on the associated category of generalized simplicial (coloured) operads. In particular, we obtain a model structure on the…

Algebraic Topology · Mathematics 2026-04-03 Gregoire Marc

We consider the classification, up to unitary equivalence, of commuting n-tuples of isometries. We pay special attention to the case when the product of the isometries is a shift of finite multiplicity, and we provide a complete…

Functional Analysis · Mathematics 2007-05-23 H. Bercovici , R. G. Douglas , C. Foias

The little $n$-disks operad is $SO(n)$ and $O(n)$-equivariantly formal over the rationals. Equivalently, the oriented and unoriented framed little disks operads are rationally formal as $\infty$-operads.

Algebraic Topology · Mathematics 2026-05-26 Pedro Boavida de Brito , Joana Cirici , Geoffroy Horel

Since their introduction by Beilinson-Drinfeld \cite{BD,Opers1}, opers have seen several generalizations. In \cite{BSY} a higher rank analog was studied, named {generalized $B$-opers}, where the successive quotients of the oper filtration…

Algebraic Geometry · Mathematics 2021-05-25 Indranil Biswas , Laura P. Schaposnik , Mengxue Yang

In this paper we prove the equivalence of two symmetric monoidal $\infty$-categories of $\infty$-operads, the one defined in Lurie's book on Higher Algebra and the one based on dendroidal spaces. V.2 Some corrections made and exposition…

Category Theory · Mathematics 2024-10-10 Vladimir Hinich , Ieke Moerdijk

Adams operations are the natural transformations of the representation ring functor on the category of finite groups, and they are one way to describe the usual lambda-ring structure on these rings. From the representation-theoretical point…

Representation Theory · Mathematics 2021-05-03 Ehud Meir , Markus Szymik

We apply the operadic modeling of brace $B_{\infty}$ algebras, as developed by Gerstenhaber and Voronov, to the context of Hopf algebroids in the sense of Xu. Specifically, we construct a strict $B_{\infty}$ isomorphism between the type I…

Quantum Algebra · Mathematics 2025-08-05 Jiahao Cheng , Zhuo Chen , Yu Qiao

Jordan operator algebras are norm-closed spaces of operators on a Hilbert space with a^2 in A for all a in A. In two recent papers by the authors and Neal, a theory for these spaces was developed. It was shown there that much of the theory…

Operator Algebras · Mathematics 2018-12-27 David P. Blecher , Zhenhua Wang

We take the first steps towards a better understanding of continuous orbit equivalence, i.e., topological orbit equivalence with continuous cocycles. First, we characterise continuous orbit equivalence in terms of isomorphisms of C*-crossed…

Dynamical Systems · Mathematics 2015-03-06 Xin Li

We introduce an explicit combinatorial characterization of the minimal model ${\cal O}_{\infty}$ of the coloured operad ${\cal O}$ encoding non-symmetric operads. In our description of ${\cal O}_{\infty}$, the spaces of operations are…

Algebraic Topology · Mathematics 2019-11-26 Jovana Obradović

In this paper, we describe families of those bounded linear operators on a separable Hilbert space that are simultaneously unitarily equivalent to integral operators on $L_2(R)$ with bounded and arbitrarily smooth Carleman kernels. The main…

Spectral Theory · Mathematics 2007-05-23 Igor M. Novitskii

We study exactness of groups and establish a characterization of exact groups in terms of the existence of a continuous linear operator, called an invariant expectation, whose properties make it a weak counterpart of an invariant mean on a…

Functional Analysis · Mathematics 2011-08-09 Ronald G. Douglas , Piotr W. Nowak

We study algebras of bounded noncommutative (nc) functions on unit balls of operator spaces (nc operator balls) and on their subvarieties. Considering the example of the nc unit polydisk we show that these algebras, while having a natural…

Operator Algebras · Mathematics 2025-04-15 Jeet Sampat , Orr Shalit

In this expository paper, we explain a formula for the multiplicities of the index of an equivariant transversally elliptic operator on a $G$-manifold. The formula is a sum of integrals over blowups of the strata of the group action and…

Differential Geometry · Mathematics 2021-01-28 Jochen Brüning , Franz W. Kamber , Ken Richardson

This is a survey of a variety of equivariant (co)homology theories for operator algebras. We briefly discuss a background on equivariant theories, such as equivariant $K$-theory and equivariant cyclic homology. As the main focus, we discuss…

Operator Algebras · Mathematics 2019-02-12 Massoud Amini , Ahmad Shirinkalam

We suppose that $G$ is a locally compact abelian group, $Y$ is a measure space, and $H$ is a reproducing kernel Hilbert space on $G\times Y$ such that $H$ is naturally embedded into $L^2(G\times Y)$ and it is invariant under the…

Operator Algebras · Mathematics 2025-04-29 Shubham R. Bais , Egor A. Maximenko , D. Venku Naidu
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