Tue, 08 May 2018

16:00 - 17:00
L3

“Perseverance and intelligence, but no genius”: Mary Somerville's theory of differences

Brigitte Stenhouse
(The Open University)
Abstract

Part of the series 'What do historians of mathematics do?'

In 1873 the Personal Recollections from Early Life to Old Age of Mary Somerville were published, containing detailed descriptions of her life as a 19th century philosopher, mathematician and advocate of women's rights. In an early draft of this work, Somerville reiterated the widely held view that a fundamental difference between men and women was the latter's lack of originality, or 'genius'.

In my talk I will examine how Somerville's view was influenced by the historic treatment of women, both within scientific research, scientific institutions and wider society. By building on my doctoral research I will also suggest an alternative viewpoint in which her work in the differential calculus can be seen as original, with a focus on her 1834 treatise On the Theory of Differences.

Tue, 01 May 2018

16:00 - 17:00
L3

“The World Is Round. Or, Is It, Really?” A Global History of Mathematics in the 17th Century

Tomoko L. Kitagawa
(UC Berkeley & Oxford Centre for Global History)
Abstract

Part of the series 'What do historians of mathematics do?'

In this talk, we will survey the movement of mathematical ideas in the 17th century. We will explore, in particular, the mathematical cultures of Paris, Amsterdam, Rome, Cape Town, Goa, Kyoto, Beijing, and London, as well as the journey of mathematical knowledge on a global scale. As it will be an ambitious task to complete a round-the-world history tour in an hour, the focus will be on East Asia. By employing the digital humanities technique, this presentation will use digital media to effectively show historical sources and help the audience imagine the world as a “round” entity when we discuss a global history of mathematics.

Thu, 24 May 2018
16:00
C5

Witten-Reshetikhin-Turaev invariants

William Petersen
(Aarhus University)
Abstract

The Witten-Reshetikhin-Turaev invariant Z(X,K) of a closed oriented three-manifold X containing a knot K, was originally introduced by Witten in order to extend the Jones polynomial of knots  in terms of Chern-Simons theory. Classically, the Jones polynomial is defined for a knot inside the three-sphere in  a combinatorial manner. In Witten's approach, the Jones polynomial J(K) emerge as the expectation value of a certain observable in Chern-Simons theory, which makes sense when K is embedded in any closed oriented three-manifold X. Moreover; he proposed that these invariants should be extendable to so-called topological quantum field theories (TQFT's). There is a catch; Witten's ideas relied on Feynman path integrals, which made them unrigorous from a mathematical point of view. However; TQFT's extending the Jones polynomial were subsequently constructed mathematically through combinatorial means by Reshetikhin and Turaev. In this talk, I shall expand slightly on the historical motivation of WRT invariants, introduce the formalism of TQFT's, and present some of the open problems concerning WRT invariants. The guiding motif will be the analogy between TQFT and quantum field theory.

Wed, 21 Feb 2018

16:00 - 17:00
C5

CAT(0) cube complexes with prescribed local geometry and fly maps.

Federico Vigolio
(University of Oxford)
Abstract

Cube Complexes with Coupled Links (CLCC) are a special family of non-positively curved cube complexes that are constructed by specifying what the links of their vertices should be. In this talk I will introduce the construction of CLCCs and try to motivate it by explaining how one can use information about the local geometry of a cube complex to deduce global properties of its fundamental group (e.g. hyperbolicity and cohomological dimension). On the way, I will also explain what fly maps are and how to use them to deduce that a CAT(0) cube complex is hyperbolic.

Thu, 07 Jun 2018
16:00
C5

From Equivariant Cohomology to Equivariant Symplectic Cohomology

Todd Liebenschutz-Jones
(Oxford University)
Abstract

Equivariant cohomology is adapted from ordinary cohomology to better capture the action of a group on a topological space. In Floer theory, given an autonomous Hamiltonian, there is a natural action of the circle on 1-periodic flowlines given by time translation. Combining these two ideas leads to the definition of  $S^1$-equivariant symplectic cohomology. In this talk, I will introduce these ideas and explain how they are related. I will not assume prior knowledge of Floer theory.

Wed, 25 Apr 2018
16:00
C5

Symplectic cohomology and its (non)vanishing

Filip Zivanovic
(Oxford University)
Abstract

Symplectic cohomology is a Floer cohomology invariant of compact symplectic manifolds 
with contact type boundary, or of open symplectic manifolds with a certain geometry 
at the infinity. It is a graded unital K-algebra related to quantum cohomology, 
and for cotangent bundle, it recovers the homology of a loop space. During the talk 
I will define symplectic cohomology and show some of the results on its (non) vanishing. 
Time permitting, I will also mention natural TQFT algebraic structure on it.

Thu, 17 May 2018
16:00
C5

Vertex algebras and categorical Kirwan surjectivity

Jacob Gross
(Oxford University)
Abstract

The Grojnowski-Nakajima theorem states that the direct sum of the homologies of the Hilbert schemes on n points on an algebraic surface is an irreducible highest weight representation of an infinite-dimensional Heisenberg superalgebra. We present an idea to rederive the Grojnowski-Nakajima theorem using Halpern-Leistner's categorical Kirwan surjectivity theorem and Joyce's theorem that the homology of a moduli space of sheaves is a vertex algebra. We compute the homology of the moduli stack of perfect complexes of coherent sheaves on a smooth quasi-projective variety X, identify it as a (modified) lattice vertex algebra on the Lawson homology of X, and explain its relevance to the aforementioned problem.

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