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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Restricting modular spin representations of symmetric and alternating groups /

Phillips, Aaron M., January 2003 (has links)
Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 69-71). Also available for download via the World Wide Web; free to University of Oregon users.
2

Restriktionen von Darstellungen der verallgemeinerten Lorentzgruppen auf Untergruppen

Herttrich, Michael. January 1976 (has links)
Thesis--Bonn. / Extra t.p. with thesis statement inserted. Includes bibliographical references (p. 107-108).
3

Restriktionen von Darstellungen der verallgemeinerten Lorentzgruppen auf Untergruppen

Herttrich, Michael. January 1976 (has links)
Thesis--Bonn. / Extra t.p. with thesis statement inserted. Includes bibliographical references (p. 107-108).
4

Matrix coefficients and representations of real reductive groups /

Sun, Binyong. January 2004 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 75-76). Also available in electronic version. Access restricted to campus users.
5

Free and linear representations of outer automorphism groups of free groups

Kielak, Dawid January 2012 (has links)
For various values of n and m we investigate homomorphisms from Out(F_n) to Out(F_m) and from Out(F_n) to GL_m(K), i.e. the free and linear representations of Out(F_n) respectively. By means of a series of arguments revolving around the representation theory of finite symmetric subgroups of Out(F_n) we prove that each homomorphism from Out(F_n) to GL_m(K) factors through the natural map p_n from Out(F_n) to GL(H_1(F_n,Z)) = GL_n(Z) whenever n=3, m < 7 and char(K) is not an element of {2,3}, and whenever n>5, m< n(n+1)/2 and char(K) is not an element of {2,3,...,n+1}. We also construct a new infinite family of linear representations of Out(F_n) (where n > 2), which do not factor through p_n. When n is odd these have the smallest dimension among all known representations of Out(F_n) with this property. Using the above results we establish that the image of every homomorphism from Out(F_n) to Out(F_m) is finite whenever n=3 and n < m < 6, and of cardinality at most 2 whenever n > 5 and n < m < n(n-1)/2. We further show that the image is finite when n(n-1)/2 -1 < m < n(n+1)/2. We also consider the structure of normal finite index subgroups of Out(F_n). If N is such then we prove that if the derived subgroup of the intersection of N with the Torelli subgroup T_n < Out(F_n) contains some term of the lower central series of T_n then the abelianisation of N is finite.
6

Approximate representations of groups

De Chiffre, Marcus 31 August 2018 (has links)
In this thesis, we consider various notions of approximate representations of groups. Loosely speaking, an approximate representation is a map from a group into the unitary operators on a Hilbert space that satisfies the homomorphism equation up to a small error. Maps that are close to actual representations are trivial examples of approximate representations, and a natural question to ask is whether all approximate representations of a given group arise in this way. A group with this property is called stable. In joint work with Lev Glebsky, Alexander Lubotzky and Andreas Thom, we approach the stability question in the setting of local asymptotic representations. We provide sufficient condition in terms of cohomology vanishing for a finitely presented group to be stable. We use this result to provide new examples of groups that are stable with respect to the Frobenius norm, including the first examples of groups that are not Frobenius approximable. In joint work with Narutaka Ozawa and Andreas Thom, we generalize a theorem by Gowers and Hatami about maps with non-vanishing uniformity norm. We use this to prove a very general stability result for uniform epsilon-representations of amenable groups which subsumes results by both Gowers-Hatami and Kazhdan.
7

Invariants numériques de catégories de fusion : calculs et applications / Numerical invariants of fusion categories : calculations and applications

Mignard, Michaël 14 December 2017 (has links)
Les catégories de fusion pointées sont des catégories de fusion pour lesquelles les objets simples sont inversibles. Nous développons des méthodes basés par ordinateur pour classifier les catégories pointées à équivalence de Morita près, et les appliquons aux catégories pointées de dimensions comprises entre 2 et 32. Nous prouvons qu'il existe 1126 classes de Morita pour de telles catégories. Aussi, nous prouvons que les indicateurs de Frobenius-Schur du centre d'une catégorie pointée de dimension inférieure à 32, accompagnés de structure enrubannée de ce centre, déterminent sa classe de Morita. Ceci est faux en général: les données modulaires, et donc a fortiori les indicateurs et structures enrubannées, ne distinguent pas les catégories modulaires. Nous donnons une famille d'exemples ; en réalité, il existe un nombre arbitrairement grand de catégories modulaires deux-à-deux non équivalentes qui peuvent partager les mêmes données modulaires. / Pointed fusion categories are fusion categories in which all simple objects are invertible. We develop computer-based methods to classify pointed categories up to Morita equivalence, and apply them to pointed fusion categories of dimension from 2 to 31. We prove that there are 1126 Morita classes of such categories. Also, we prove that the Frobenius-Schur indicators of the centers of a pointed category of dimension less than 32, along with its ribbon twist, determine its Morita class. This is not true in general: the modular data, and a fortiori the indicators and the ribbon twists, do not distinguish modular categories. We give a family of examples; in fact, arbitrarly many pairwise non-equivalent modular categories can share the same modular data.

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