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Pathwise Integration and functional calculus for paths with finite quadratic variation

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Ananova-A-2019-PhD-ThesisThesis791.95 kBAdobe PDFView/Open
Title: Pathwise Integration and functional calculus for paths with finite quadratic variation
Authors: Ananova, Anna
Item Type: Thesis or dissertation
Abstract: This thesis develops a pathwise calculus for non-anticipative functionals of paths with finite quadratic variation and studies its relation with the theory of controlled paths. We study the mathematical properties of a pathwise integral defined as a limit of Riemann sums for a class of non-anticipative gradient-type integrands. We establish for this integral a pathwise isometry property, analogous to the well-known Ito isometry for stochastic integrals, and obtain a pathwise 'signal plus noise' decomposition as a unique sum of a pathwise integral and a component with zero quadratic variation for regular functionals of an irregular path with non-vanishing quadratic variation. Our results are strictly pathwise but apply to typical paths of continuous semimartingales. In the second part of the thesis we explore the relations between this non-anticipative functional calculus and the theory of controlled paths. We show that a regular functional generates a family of controlled paths whose `Gubinelli derivative' may be represented as a directional derivative. Conversely, we show that a family of controlled paths parameterized by the underlying control function may be represented as a vertically differentiable functional. This result leads to a chain rule for controlled paths and systematic way of constructing them. In the last part of the thesis we extend these results to functionals of discontinuous paths which are right-continuous with left limits.
Content Version: Open Access
Issue Date: Nov-2018
Date Awarded: Jan-2019
URI: http://hdl.handle.net/10044/1/66091
DOI: https://doi.org/10.25560/66091
Copyright Statement: Creative Commons Attribution NonCommercial Licence
Supervisor: Cont, Rama
Sponsor/Funder: Imperial College London
Department: Mathematics
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Mathematics PhD theses