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In the (covariant) topos approach to quantum theory by Heunen, Landsman and Spitters, one associates to each unital C*-algebra, A, a topos T(A) of sheaves on a locale and a commutative C*-algebra, a, within that topos. The Gelfand spectrum…

Category Theory · Mathematics 2014-08-04 Bas Spitters , Steven Vickers , Sander Wolters

In this paper, we discuss the associated family of harmonic maps $\mathcal{F}: M \rightarrow G/K$ from a Riemann surface $M$ into inner symmetric spaces of compact or non-compact type which are either algebraic or totally symmetric. These…

Differential Geometry · Mathematics 2024-08-23 Josef F. Dorfmeister , Peng Wang

In this paper we give algebraic models for rational G-spectra for a compact Lie group G when the geometric isotropy is restricted to lie in a 1-dimensional block of conjugacy classes. This includes all blocks of all groups of dimension 1,…

Algebraic Topology · Mathematics 2025-01-22 J. P. C. Greenlees

The author's recent results on spectral invariant dense subalgebras of C*-algebras associated with dynamical systems are summarized. If G is a compactly generated polynomial growth Type R Lie group, and the action of G on S(M) (Schwartz…

funct-an · Mathematics 2016-02-15 Larry B. Schweitzer

We obtain some results that relate the Connes spectrum with the innerness of automorphisms in the fixed point local multiplier algebra. The results are variants and/or extensions of corresponding results of Olesen, Pedersen and Stormer [6],…

Operator Algebras · Mathematics 2007-05-23 Raluca Dumitru , Costel Peligrad , Bogdan Visinescu

Let L^1(G) and M(G) be group algebra and measure algebra of a locally compact group G, respectively and D:L^1(G)-->M(G) be a continuous linear map. We consider D behaving like derivation or anti-derivation at orthogonal elements for several…

Functional Analysis · Mathematics 2020-01-27 Hoger Ghahramani

Let $G$ be a locally compact group, and let $B(G)$ denote its Fourier--Stieltjes algebra. We show that $B(G)$ is Connes-amenable if and only if $G$ is almost abelian.

Functional Analysis · Mathematics 2016-05-24 Volker Runde , Faruk Uygul

We develop a new approach to geometric quantization using the theory of convergence of metric measure spaces. Given a family of K\"ahler polarizations converging to a non-singular real polarization on a prequantized symplectic manifold, we…

Differential Geometry · Mathematics 2023-05-03 Kota Hattori , Mayuko Yamashita

In this note we reformulate the spectral side of the Weyl law in the language of the matrix-valued quantisation on compact Lie groups.

Spectral Theory · Mathematics 2024-01-17 Duván Cardona , Julio Delgado , Michael Ruzhansky

This paper introduces the notion of local spectral expansion of a simplicial complex as a possible analogue of spectral expansion defined for graphs. We show the condition of local spectral expansion has several nice implications. For…

Combinatorics · Mathematics 2015-03-26 Izhar Oppenheim

This is a survey of what is known and/or conjectured about the prime and primitive spectra of quantum algebras, of quantized coordinate rings in particular. The topological structure of these spectra, their relations to classical affine…

Quantum Algebra · Mathematics 2022-11-29 K. R. Goodearl

Categorial methods for generating new local algebras from old ones are presented. A direct proof of the differential structure of the prolongations of a manifold is proposed.

Category Theory · Mathematics 2007-09-05 Margherita Barile , Fiorella Barone , Wlodzimierz M. Tulczyjew

In this paper we start studying spectral properties of the Fourier-Stieltjes algebras, largely following Zafran's work on the algebra of measures on a locally compact group. We show that for a large class of discrete groups the Wiener-Pitt…

Functional Analysis · Mathematics 2019-05-30 Przemysław Ohrysko , Mateusz Wasilewski

We give a description of the value of a finitary localizing invariant, such as algebraic $K$-theory, on the category of sheaves on a locally coherent space $X$. This in particular includes all spaces that arise as spectra of commutative…

K-Theory and Homology · Mathematics 2025-10-16 Georg Lehner

For a discrete group G with Fourier algebra A(G), we study the topological centre $Z_t$ of the bidual. If G is amenable, then $Z_t$ = A(G). But if G contains a non-abelian free group $F_r$, we show that $Z_t$ is strictly larger than A(G).…

Functional Analysis · Mathematics 2021-04-27 Viktor Losert

In this paper the inverse of the quaternionic Fourier transform on locally compact abelian groups is verified.

Functional Analysis · Mathematics 2020-01-07 Majid Jabbar Saadan , Mohammad Janfada , Radjab Ali Kamyabi Gol

A locally compact group $G$ is compact if and only if $L^1(G)$ is an ideal in $L^1(G)^{**}$, and the Fourier algebra $A(G)$ of $G$ is an ideal in $A(G)^{**}$ if and only if $G$ is discrete. On the other hand, $G$ is discrete if and only if…

Operator Algebras · Mathematics 2008-12-11 Volker Runde

Let G be a locally compact group. In this note, we characterise non-degenerate *-representations of A_\Phi(G) and B_\Phi(G). We also study spectral subspaces associated to a non-degenerate Banach space representation of A_\Phi(G).

Functional Analysis · Mathematics 2019-03-13 Rattan Lal , N. Shravan Kumar

Let G be a simply connected semisimple algebraic group over an algebraically closed field k of positive characteristic. We will untwist the structure of G-modules by a newly found splitting of the Frobenius endomorphism on the algebra of…

Representation Theory · Mathematics 2010-04-13 Michel Gros , Masaharu Kaneda

We study the real spectrum compactification of character varieties of finitely generated groups in semisimple Lie groups. This provides a compactification with good topological properties, and we interpret the boundary points in terms of…

Group Theory · Mathematics 2025-07-15 Marc Burger , Alessandra Iozzi , Anne Parreau , Maria Beatrice Pozzetti