Oxford Mathematician Dan Ciubotaru talks about his recent research in Representation Theory.
The critical threshold for Bargmann-Fock percolation
Abstract
Let f be the planar Bargmann-Fock field, i.e. the analytic Gaussian field with covariance kernel exp(-|x-y|^2/2). We compute the critical point for the percolation model induced by the level sets of f. More precisely, we prove that there exists a.s. an unbounded component in {f>p} if and only if p<0. Such a percolation model has been studied recently by Beffara-Gayet and Beliaev-Muirhead. One important aspect of our work is a derivation of a (KKL-type) sharp threshold result for correlated Gaussian variables. The idea to use a KKL-type result to compute a critical point goes back to Bollobás-Riordan. This is joint work with Alejandro Rivera.
15:00
Full orbit sequences in affine spaces
Abstract
Let n be a positive integer. In this talk we provide a recipe to
construct full orbit sequences in the affine n-dimensional space over a
finite field. For n=1 our construction covers the case of the well
studied pseudorandom number generator ICG.
This is a joint work with Federico Amadio Guidi.
5th Oxford International Workshop on Neuron and Brain Mechanics
Abstract
The 5th Oxford Neuron and Brain Mechanics Workshop will take place on 22 and 23 March 2018, in St Hugh’s College, Oxford. The event includes international and UK speakers from a wide variety of disciplines, collectively working on Traumatic Brain Injury, Brain Mechanics and Trauma, and Neurons research.
The aim is to foster new collaborative partnerships and facilitate the dissemination of ideas from researchers in different fields related to the study of brain mechanics, including pathology, injury and healing.
Focussing on a multi-disciplinary and collaborative approach to aspects of brain mechanics research, the workshop will present topics from areas including Medical, Neuroimaging, Neuromechanics and mechanics, Neuroscience, Neurobiology and commercial applications within medicine.
This workshop is the latest in a series of events established by the members of the International Brain Mechanics and Trauma Lab (IBMTL) initiative *(www.brainmech.ox.ac.uk) in collaboration with St Hugh’s College, Oxford.
Speakers
Professor Lee Goldstein MD, Boston University
Professor David Sharp, Imperial College London
Dr Ari Ercole, University of Cambridge
Professor Jochen Guck, BIOTEC Dresden
Dr Elisa Figallo, Finceramica SPA
Dr Mike Jones, Cardiff University
Professor Ellen Kuhl, Stanford University
Mr Tim Lawrence, University of Oxford
Professor Zoltan Molnar, University of Oxford
Dr Fatiha Nothias, University Pierre & Marie Curie
Professor Stam Sotiropoulos, University of Nottingham
Professor Michael Sutcliffe, University of Cambridge
Professor Alain Goriely, University of Oxford
Professor Antoine Jérusalem, University of Oxford
Everybody is welcome to attend but (free) registration is required.
https://www.eventbrite.co.uk/e/5th-oxford-international-workshop-on-neu…
Students and postdocs are invited to exhibit a poster.
For further information on the workshop, or exhibiting a poster, please contact: @email
The workshop is generously supported by the ERC’s ‘Computational Multiscale Neuron Mechanics’ grant (COMUNEM, grant # 306587) and St Hugh’s College, Oxford.
The International Brain Mechanics and Trauma Lab, based in Oxford, is an international collaboration on projects related to brain mechanics and trauma. This multidisciplinary team is motivated by the need to study brain cell and tissue mechanics and its relation with brain functions, diseases or trauma.
16:00
Character varieties and (\varphi_L,\Gamma_L)-modules
Abstract
After reviewing old work with Teitelbaum, in which we constructed the character variety X of the additive group o_L in a finite extension L/Q_p and established the Fourier isomorphism for the distribution algebra of o_L, I will briefly report on more recent work with Berger and Xie, in which we establish the theory of (\varphi_L,\Gamma_L)-modules over X and relate it to Galois representations. Then I will discuss an ongoing project with Venjakob. Our goal is to use this theory over X for Iwasawa theory.
2D problems in groups
Abstract
The Algebraic Torus Theorem
Abstract
I will discuss a wonderful structure theorem for finitely generated group containing a codimension one polycyclic-by-finite subgroup, due to Martin Dunwoody and Eric Swenson. I will explain how the theorem is motivated by the torus theorem for 3-manifolds, and examine some of the consequences of this theorem.
Tropical Coordinates on the Space of Persistence Barcodes
Abstract
The aim of applied topology is to use and develop topological methods for applied mathematics, science and engineering. One of the main tools is persistent homology, an adaptation of classical homology, which assigns a barcode, i.e., a collection of intervals, to a finite metric space. Because of the nature of the invariant, barcodes are not well adapted for use by practitioners in machine learning tasks. We can circumvent this problem by assigning numerical quantities to barcodes, and these outputs can then be used as input to standard algorithms. I will explain how we can use tropical-like functions to coordinatize the space of persistence barcodes. These coordinates are stable with respect to the bottleneck and Wasserstein distances. I will also show how they can be used in practice.