Past Seminars

8 September 2021
09:00
Abstract

Although a multidimensional data array can be very large, it may contain coherence patterns much smaller in size. For example, we may need to detect a subset of genes that co-express under a subset of conditions. In this presentation, we discuss our recently developed co-clustering algorithms for the extraction and analysis of coherent patterns in big datasets. In our method, a co-cluster, corresponding to a coherent pattern, is represented as a low-rank tensor and it can be detected from the intersection of hyperplanes in a high dimensional data space. Our method has been used successfully for DNA and protein data analysis, disease diagnosis, drug therapeutic effect assessment, and feature selection in human facial expression classification. Our method can also be useful for many other real-world data mining, image processing and pattern recognition applications.

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6 July 2021
17:00
Ingrid Daubechies

Further Information: 

A collaborative art installation celebrating the joy, creativity and beauty of mathematics has been in the works for the past two years, and will soon be ready to emerge from its long gestation. The original idea, conceived by textile artist Dominique Ehrmann and mathematician Ingrid Daubechies inspired a team of 24 Mathemalchemists to work together, transforming the whole conception in the process, and bringing their individual expertise and whimsy to a large installation.

Despite the challenges of Covid-19, the team created a fantasy world where herons haul up nets loaded with special knots in the Knotical scene, a tortoise meditates while ambling along Zeno's path, chipmunks and squirrels ponder the mysteries of prime numbers, and a cat named Arnold bakes cookies that tile the plane in the Mandelbrot bakery; and a myriad more mathematical ideas swirl through the air.

This presentation will introduce some of the ideas and components, and show the team at work. Here's a sneak preview:
www.mathemalchemy.org
@mathemalchemy

Multi-award winning Ingrid Daubechies is James B. Duke Distinguished Professor of Mathematics and Electrical and Computer Engineering at Duke University.

Watch (no need to register and it will remain available after broadcast):
Oxford Mathematics YouTube

The Oxford Mathematics Public Lectures are generously supported by XTX Markets.

  • Oxford Mathematics Public Lectures
29 June 2021
14:00
Stefanos Aretakis
Abstract

We will present the precise late-time asymptotics for scalar fields on both extremal and sub-extremal black holes including the full Reissner-Nordstrom family and the subextremal Kerr family. Asymptotics for higher angular modes will be presented for all cases. Applications in observational signatures will also be discussed. This work is joint with Y. Angelopoulos (Caltech) and D. Gajic (Cambridge)

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28 June 2021
11:30
Marko Berghoff
Abstract

I will present work in progress with Erik Panzer, Matteo Parisi and Ömer Gürdoğan on the analytic structure of Feynman(esque) integrals: We consider integrals of meromorphic differential forms over relative cycles in a compact complex manifold, the underlying geometry encoded in a certain (parameter dependant) subspace arrangement (e.g. Feynman integrals in their parametric representation). I will explain how the analytic struture of such integrals can be studied via methods from differential topology; this is the seminal work by Pham et al (using tools and methods developed by Leray, Thom, Picard-Lefschetz etc.). Although their work covers a very general setup, the case we need for Feynman integrals has never been worked out in full detail. I will comment on the gaps that have to be filled to make the theory work, then discuss how much information about the analytic structure of integrals can be derived from a careful study of the corresponding subspace arrangement.

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24 June 2021
17:00
Sandy Pentland

Further Information: 

Using data from four continents, we show that diversity of consumption and of diversity of social exposure are perhaps the single most powerful predictor of life outcomes such as increasing neighborhood GDP, increasing individual wealth, and promoting intergenerational mobility, even after controlling for variables such as population density, housing price, and geographic centrality. The effects of diversity in promoting opportunity are causal, and inequality in opportunity stems more from social norms that promote segregation than from physical segregation. Policies to promote more equal opportunities within cities seem practical.

You can register here. Everyone is welcome.

22 June 2021
11:00
Roger Penrose et al.
Abstract

This is a joint GR-QFT seminar, to celebrate in advance the 90th birthday of Roger Penrose later in the summer, comprising 9 talks on conformal cyclic cosmology.  The provisional schedule is as follows:

11:00 Roger Penrose (Oxford, UK) : The Initial Driving Forces Behind CCC

11:10 Paul Tod (Oxford, UK) : Questions for CCC

11:20 Vahe Gurzadyan (Yerevan, Armenia): CCC predictions and CMB

11:30 Krzysztof Meissner (Warsaw, Poland): Perfect fluids in CCC

11:40 Daniel An (SUNY, USA) : Finding information in the Cosmic Microwave Background data

11:50 Jörg Frauendiener (Otago, New Zealand) : Impulsive waves in de Sitter space and their impact on the present aeon

12:00 Pawel Nurowski (Warsaw, Poland and Guangdong Technion, China): Poincare-Einstein expansion and CCC

12:10 Luis Campusano (FCFM, Chile) : (Very) Large Quasar Groups

12:20 Roger Penrose (Oxford, UK) : What has CCC achieved; where can it go from here?

  • Quantum Field Theory Seminar
21 June 2021
16:00
Abstract

Abstract: In this talk we try to establish an analytic framework for studying Set-Valued Backward Stochastic Differential Equations (SVBSDE for short), motivated largely by the current studies of dynamic set-valued risk measures for multi-asset or network-based financial models. Our framework will be based on the notion of Hukuhara difference between sets, in order to compensate the lack of “inverse” operation of the traditional Minkowski addition, whence the vector space structure, in traditional set-valued analysis. We shall examine and establish a useful foundation of set-valued stochastic analysis under this algebraic framework, including some fundamental issues regarding Aumann-Itˆo integrals, especially when it is connected to the martingale representation theorem. We shall identify some fundamental challenges and propose some extensions of the existing theory that are necessary to study the SVBSDEs. This talk is based on the joint works with C¸ a˘gın Ararat and Wenqian Wu.

  • Stochastic Analysis & Mathematical Finance Seminars
21 June 2021
16:00
Natalie Evans
Abstract

The Hardy-Littlewood generalised twin prime conjecture states an asymptotic formula for the number of primes $p\le X$ such that $p+h$ is prime for any non-zero even integer $h$. While this conjecture remains wide open, Matom\"{a}ki, Radziwi{\l}{\l} and Tao proved that it holds on average over $h$, improving on a previous result of Mikawa. In this talk we will discuss an almost prime analogue of the Hardy-Littlewood conjecture for which we can go beyond what is known for primes. We will describe some recent work in which we prove an asymptotic formula for the number of almost primes $n=p_1p_2 \le X$ such that $n+h$ has exactly two prime factors which holds for a very short average over $h$.

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  • Junior Number Theory Seminar

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