Sökning: "groupoid"
Visar resultat 1 - 5 av 9 avhandlingar innehållade ordet groupoid.
1. A Categorical Study of Composition Algebras via Group Actions and Triality
Sammanfattning : A composition algebra is a non-zero algebra endowed with a strictly non-degenerate, multiplicative quadratic form. Finite-dimensional composition algebras exist only in dimension 1, 2, 4 and 8 and are in general not associative or unital. Over the real numbers, such algebras are division algebras if and only if they are absolute valued, i.e. LÄS MER
2. Modeling mapping spaces with short hammocks
Sammanfattning : We construct a category of short hammocks and show that it has the weak homotopy type of mapping spaces. In doing so we tackle the problem of applying the nerve to large categories without the use of multiple universes. We also explore what the mapping space is. LÄS MER
3. Admissible covers, modular operads and modular forms
Sammanfattning : This thesis contains three articles related to operads and moduli spaces of admissible covers of curves. In Paper A we isolate cohomology classes coming from modular forms inside a certain space of admissible covers, thereby showing that this moduli space can be used as a substitute for a Kuga–Sato variety. LÄS MER
4. Localic Categories of Models and Categorical Aspects of Intuitionistic Ramified Type Theory
Sammanfattning : This thesis contains three papers, all in the general area of categorical logic, together with an introductory part with some minor results and proofs of known results which does not appear to be (easily) available in the literature.In Papers I and II we investigate the formal system Intuitionistic Ramified Type Theory (IRTT), introduced by Erik Palmgren, as an approach to predicative topos theory. LÄS MER
5. Amenable-like properties of étale groupoids
Sammanfattning : This thesis consists of three papers related to analytic and representation theoretic properties of étale groupoids.In the first paper, we characterize algebraically the type I and CCR property for ample groupoids and their non-commutative duals: Boolean inverse semigroups. Our results use and generalize Thoma’s work on discrete groups. LÄS MER