# Harmonic analysis on 2-step stratified Lie groups without the Moore-Wolf condition

 dc.contributor.advisor Witt, Ingo Prof. Dr. dc.contributor.author Yang, Zhipeng dc.date.accessioned 2022-04-07T13:37:36Z dc.date.available 2022-04-14T00:50:27Z dc.date.issued 2022-04-07 dc.identifier.uri http://resolver.sub.uni-goettingen.de/purl?ediss-11858/13975 dc.identifier.uri http://dx.doi.org/10.53846/goediss-9171 dc.language.iso eng de dc.rights.uri http://creativecommons.org/licenses/by/4.0/ dc.subject.ddc 510 de dc.title Harmonic analysis on 2-step stratified Lie groups without the Moore-Wolf condition de dc.type doctoralThesis de dc.contributor.referee Witt, Ingo Prof. Dr. dc.date.examination 2022-03-09 de dc.description.abstracteng In this thesis we investigate harmonic analysis on a particular class of sub-Riemannian manifold, namely the 2-step stratified Lie groups $\mathbb{G}$, as well as its applications in partial differential equations. This class consists a breadth of interesting geometric objects such as Heisenberg group and H-type Lie group, which can be seen as a meaningful extension of classical theories. de After reviewing some main definitions and properties in Chapter 2, we start to study the most important representation of $\mathbb{G}$, the so-called Schr\"{o}dinger representation on $L^2(\mathbb{G})$, and then we prove the Stone-von Neumann theorem for the 2-step stratified Lie groups. In Chapter 3 we also study the Fourier transforms and define the $(\lambda,\nu)$-Wigner and $(\lambda,\nu)$-Weyl transform related to $\mathbb{G}$, we then show some properties of these transforms, which can help us to compute the sub-Laplacian and the $\lambda$-twisted sub-Laplacian. Moreover, in this chapter we demonstrate the beautiful interplay between the representation theory on $\mathbb{G}$ and the classical expansions in terms of Hermite functions and Lagueere functions, As applications, a global calculus of pseudo-differential operator on 2-step stratified Lie groups $\mathbb{G}$ is introduced in the fourth chapter. It relies on the explicit knowledge of the irreducible unitary representations of $\mathbb{G}$, which then allows one to reduce the analysis to study of a rescaled harmonic oscillator on unitary dual $\hat{\mathbb{G}}$. The sub-Laplacian appears as an elliptic operator in this calculus. The explicit formula for the heat kernel of the $\lambda$-twisted sub-Laplacian can be also obtained, which gives a closed formula for the heat kernel of the sub-Laplacian on $\mathbb{G}$. dc.contributor.coReferee Bahns, Dorothea Prof. Dr. dc.subject.eng harmonic analysis de dc.subject.eng nilpotent lie group de dc.identifier.urn urn:nbn:de:gbv:7-ediss-13975-2 dc.affiliation.institute Fakultät für Mathematik und Informatik de dc.subject.gokfull Mathematics (PPN61756535X) de dc.description.embargoed 2022-04-14 de dc.identifier.ppn 1799351807
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