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In this article, we define Weyl transform on second countable type - $I$ locally compact group $G,$ and as an operator on $L^2(G),$ we prove that the Weyl transform is compact when the symbol lies in $L^p(G\times \hat{G})$ with $1\leq p\leq…

Functional Analysis · Mathematics 2021-07-01 Somnath Ghosh , R. K. Srivastava

In the two papers of this series, we initiate the development of a new approach to implementing the concept of symmetry in classical field theory, based on replacing Lie groups/algebras by Lie groupoids/algebroids, which are the appropriate…

Mathematical Physics · Physics 2018-06-06 Bruno T. Costa , Michael Forger , Luiz Henrique P. Pêgas

We define a class of Riemannian and pseudo-Riemannian 2-step nilpotent Lie groups with nondegenerate centers that generalize the H-type groups of Kaplan. Examples are given and geometric properties are investigated.

Differential Geometry · Mathematics 2021-08-05 Justin M. Ryan

The celebrated Fefferman's theorems on the general form of linear functionals on the Hardy space $H^1$ over the circle group is generalized to the case of an arbitrary compact Abelian group with totally ordered dual. Several corollaries…

Functional Analysis · Mathematics 2016-11-28 A. R. Mirotin

The paper is devoted to generalizations of actions of topological groups on manifolds. Instead of a topological group, we consider a local topological group generalizing the notion of a~germ or a~neighborhood in a topological group. The…

Group Theory · Mathematics 2022-09-16 Mikhail V. Neshchadim , Andrey A. Simonov

For a second countable locally compact abelian (LCA) group $G$, we study some necessary and sufficient conditions to generate continuous Gabor frames for $L^{2}(G)$. To this end, we reformulate the generalized Zak transform proposed by…

Functional Analysis · Mathematics 2021-07-21 Z. Hamidi , F. Arabyani-Neyshaburi , R. A. Kamyabi-Gol , M. H. Sattari

We give sharp remainder terms of $L^{p}$ and weighted Hardy and Rellich inequalities on one of most general subclasses of nilpotent Lie groups, namely the class of homogeneous groups. As consequences, we obtain analogues of the generalised…

Classical Analysis and ODEs · Mathematics 2017-08-14 Michael Ruzhansky , Durvudkhan Suragan

We classify finite-dimensional nilpotent Lie algebras with $2$-dimensional central commutator ideals admitting a Lie group of automorphisms isomorphic to $SO_2(\mathbb R)$. This enables one to enlarge the class of nilpotent Lie algebras of…

Group Theory · Mathematics 2016-07-19 Giovanni Falcone , Ágota Figula

In this paper Gabor system of certain type based on the unitary dual of the Heisenberg group $\mathbb{H}^n$ is introduced and a sufficient condition is obtained for the Gabor system to be a Bessel sequence for…

Functional Analysis · Mathematics 2021-05-28 S. R. Das , R. Radha

Nilpotency for discrete groups can be defined in terms of central extensions. In this paper, the analogous definition for spaces is stated in terms of principal fibrations having infinite loop spaces as fibers, yielding a new invariant we…

Algebraic Topology · Mathematics 2017-05-30 Cristina Costoya , Jérôme Scherer , Antonio Viruel

We use the method of group contractions to relate wavelets analysis and Gabor analysis. Wavelets analysis is associated with unitary irreducible representations of the affine group while Gabor analysis is associated with unitary irreducible…

Representation Theory · Mathematics 2017-09-12 Eyal M. Subag , Ehud Moshe Baruch , Joseph L. Birman , Ady Mann

We calculate the homology of three families of 2-step nilpotent Lie (super)algebras associated with the symplectic, orthogonal, and general linear groups. The symplectic case was considered by Getzler and the main motivation for this work…

Representation Theory · Mathematics 2015-07-27 Steven V Sam

We consider an action of a compact group whose dual is archimedean linearly ordered or a direct product (or sum) of such groups on a von Neumann algebra, M. We define the generalized Hardy subspace of the Hilbert space of a standard…

Operator Algebras · Mathematics 2020-10-13 Costel Peligrad

We develop a generalized Floquet-Bloch theory for discrete torsion-free nilpotent groups by exploiting their Malcev completions. Our main result is a branching formula that relates finite-dimensional representations of a discrete nilpotent…

Differential Geometry · Mathematics 2025-11-18 Atsushi Katsuda

We survey some aspects of the pseudo-differential Weyl calculus for irreducible unitary representations of nilpotent Lie groups, ranging from the classical ideas to recently obtained results. The classical Weyl-H\"ormander calculus is…

Analysis of PDEs · Mathematics 2015-05-14 Ingrid Beltita , Daniel Beltita

In this short paper, we establish a range of Caffarelli-Kohn-Nirenberg and weighted $L^{p}$-Sobolev type inequalities on stratified Lie groups. All inequalities are obtained with sharp constants. Moreover, the equivalence of the Sobolev…

Functional Analysis · Mathematics 2017-09-26 Michael Ruzhansky , Durvudkhan Suragan , Nurgissa Yessirkegenov

The paper offers versions of Hilbert's Irreducibility Theorem for the lifting of points in a cyclic subgroup of an algebraic group to a ramified cover. A version of Bertini Theorem in this context is also obtained.

Number Theory · Mathematics 2019-12-19 Umberto Zannier

Using an algebraic point of view we present an introduction to the groupoid theory, that is, we give fundamental properties of groupoids as, uniqueness of inverses and properties of the identities, and study subgroupoids, wide subgroupoids…

Group Theory · Mathematics 2020-01-29 Jesús Ávila , Víctor Marín , Héctor Pinedo

We address the type I dichotomy for two-step nilpotent locally compact groups. Invoking work of Baggett-Kleppner, we characterize the closed points of the unitary dual of such a group $G$ purely in terms of the group structure. An algebraic…

Representation Theory · Mathematics 2025-10-01 Pierre-Emmanuel Caprace , Max Carter

A notion of L^2-homology for compact quantum groups is introduced, generalizing the classical notion for countable, discrete groups. If the compact quantum group in question has tracial Haar state, it is possible to define its L^2-Betti…

Operator Algebras · Mathematics 2008-10-02 David Kyed