Mon, 21 Oct 2019

14:15 - 15:15
L4

The pure cohomology of multiplicative quiver varieties

Kevin McGerty
(Oxford)
Further Information

Multiplicative quiver varieties are a variant of Nakajima's "additive" quiver varieties which were introduced by Crawley-Boevey and Shaw.
They arise naturally in the study of various moduli spaces, in particular in Boalch's work on irregular connections. In this talk we will discuss joint work with Tom Nevins which shows that the tautological classes for these varieties generate the largest possible subalgebra of the cohomology ring, namely the pure part.

 

Whether you are interested in Maths at Oxford. Whether you are interested in Maths. Whether you are just interested. The Oxford Mathematics Open Day is LIVE on July 3 @10am. You can watch it all, or just dip in and out. You can also ask questions in our live chat at 10.30am. Virtually come along. You are very welcome. 

www.facebook.com/OxfordMathematics

or

Mon, 28 Oct 2019
14:15
L4

The Hitchin connection in (almost) arbitrary characteristic.

Johan Martens
(Edinburgh)
Further Information

The Hitchin connection is a flat projective connection on bundles of non-abelian theta-functions over the moduli space of curves, originally introduced by Hitchin in a Kahler context.  We will describe a purely algebra-geometric construction of this connection that also works in (most)positive characteristics.  A key ingredient is an alternative to the Narasimhan-Atiyah-Bott Kahler form on the moduli space of bundles on a curve.  We will comment on the connection with some related topics, such as the Grothendieck-Katz p-curvature conjecture.  This is joint work with Baier, Bolognesi and Pauly.

 

Mon, 14 Oct 2019

14:15 - 15:15
L4

Local stability of Einstein metrics under the Ricci iteration

Tim Buttsworth
(Cornell)
Further Information

A Ricci iteration is a sequence of Riemannian metrics on a manifold such that every metric in the sequence is equal to the Ricci curvature of the next metric. These sequences of metrics were introduced by Rubinstein to provide a discretisation of the Ricci flow. In this talk, I will discuss the relationship between the Ricci iteration and the Ricci flow. I will also describe a recent result concerning the existence and convergence of Ricci iterations close to certain Einstein metrics. (Joint work with Max Hallgren)

Tue, 10 Sep 2019 09:30 -
Wed, 11 Sep 2019 18:30

ENIUS TRAINING SCHOOL, BERN | 15 BURSARIES AVAILABLE | APPLICATIONS NOW OPEN

(Swiss Institute for Translational and Entrepreneurial Medicine)
Further Information

The Training School will bring together a multi-disciplinary group of clinicians, biomedical engineers, biologists and physical scientists to present recent advances in mathematical, computational, in-vitro, and in-vivo approaches to further our understanding of fluid mechanics within the stented ureter and to identify current challenges in urinary stent design. Moreover, leading speakers from the world of industry and regulatory affairs will share their experiences of commercialisation in the medtech industry, and how they have addressed industrial and regulatory challenges when taking their “next-generation” products from bench-to-bedside.

Here is a preliminary program.

We would like to encourage Early Career Researchers (Master students, PhD students, and PostDocs) to apply as trainees, by sending their CV and a short statement (of no more than 250 words) to francesco.clavica@artorg.unibe.ch, explaining why they would like to attend the Training School. Participants are encouraged to present a poster about their work, and should send a title of their poster together with their application.

We will award 15 grants to fund accommodation, travel, and subsistence of trainees

Applications should be submitted by July 15th, and applicants will be notified by the end of July about the outcome of their application.

Instability and dripping of electrified liquid films flowing down inverted substrates
Tomlin, R Cimpeanu, R Papageorgiou, D (20 Jun 2019)

Have you ever picked up a glass to find that the coaster it was resting on remains stuck to the bottom? If so, then you have experienced the ability of fluid to stick two surfaces together. When the bottom of the glass is wetted, for example by accidentally spilling a drink, then this fluid can fill the gap between the glass and coaster. The surface tension of the liquid then provides a pulling force on the coaster that keeps it attached to the glass.

Fri, 21 Jun 2019

15:30 - 16:00
N3.12

Smoothness of Persistence

Jacob Leygonie
((Oxford University))
Abstract

We can see the simplest setting of persistence from a functional point of view: given a fixed finite simplicial complex, we have the barcode function which, given a filter function over this complex, returns the corresponding persistent diagram. The bottleneck distance induces a topology on the space of persistence diagrams, and makes the barcode function a continuous map: this is a consequence of the stability Theorem. In this presentation, I will present ongoing work that seeks to deepen our understanding of the analytic properties of the barcode function, in particular whether it can be said to be smooth. Namely, if we smoothly vary the filter function, do we get smooth changes in the resulting persistent diagram? I will introduce a notion of differentiability/smoothness for barcode valued maps, and then explain why the barcode function is smooth (but not everywhere) with respect to the choice of filter function. I will finally explain why these notions are of interest in practical optimisation/learning situations. 

Fri, 21 Jun 2019

15:00 - 15:30
N3.12

Outlier Robust Subsampling Techniques for Persistent Homology

Bernadette Stolz-Pretzer
((Oxford University))
Abstract

The amount and complexity of biological data has increased rapidly in recent years with the availability of improved biological tools. When applying persistent homology to large data sets, many of the currently available algorithms however fail due to computational complexity preventing many interesting biological applications. De Silva and Carlsson (2004) introduced the so called Witness Complex that reduces computational complexity by building simplicial complexes on a small subset of landmark points selected from the original data set. The landmark points are chosen from the data either at random or using the so called maxmin algorithm. These approaches are not ideal as the random selection tends to favour dense areas of the point cloud while the maxmin algorithm often selects outliers as landmarks. Both of these problems need to be addressed in order to make the method more applicable to biological data. We study new ways of selecting landmarks from a large data set that are robust to outliers. We further examine the effects of the different subselection methods on the persistent homology of the data.

Subscribe to