15:45
Upper bounds onReidemeistermoves
Abstract
Given any two diagrams of the same knot or link, we
provide an explicit upper bound on the number of Reidemeister moves required to
pass between them in terms of the number of crossings in each diagram. This
provides a new and conceptually simple solution to the equivalence problem for
knot and links. This is joint work with Marc Lackenby.
15:45
TBA
Abstract
Condition supercritical percolation so that the origin is enclosed by a dual circuit whose interior traps an area of n^2.
The Wulff problem concerns the shape of the circuit. We study the circuit's fluctuation. A well-known measure of this fluctuation is maximum local roughness (MLR), which is the greatest distance from a point on the circuit to the boundary of circuit's convex hull. Another is maximum facet length (MFL), the length of the longest line segment of which this convex hull is comprised.
In a forthcoming article, I will prove that
for various models including supercritical percolation, under the conditioned measure,
MLR = \Theta(n^{1/3}\log n)^{2/3}) and MFL = \Theta(n^{2/3}(log n)^{1/3}).
An important tool is a result establishing the profusion of regeneration sites in the circuit boundary. The talk will focus on deriving the main results with this tool
14:15
Self-Organised Criticality via Stochastic Partial Differential Equations
Gauge Threshold Corrections for Local String Models
Abstract
Dislocation dynamics and instability
Abstract
Dislocation channel-veins and Persist Slip Band (PSB) structures are characteristic configurations in material science. To find out the formation of these structures, the law of motion of a single dislocation should be first examined. Analogous to the local expansion in electromagnetism, the self induced stress is obtained. Then combining the empirical observations, we give a smooth mobility law of a single dislocation. The stability analysis is carried our asymptotically based on the methodology in superconducting vortices. Then numerical results are presented to validate linear stability analysis. Finally, based on the evidence given by the linear stability analysis, numerical experiments on the non-linear evolution are carried out.
16:30
*My Nonlinear Odyssey : Analytics*, * Simulation & Visualization *
Abstract
An overview of the early history of the soliton (1960-1970) and equipartition in nonlinear 1D lattices : From Fermi-Pasta-Ulam to Korteweg de Vries, to Nonlinear Schrodinger*…., and recent developments .
14:15
Stochastic version of the rule "Buy and Hold"
Abstract
For a logarithmic utility function we extend our rezult with Xu and Zhou for case of the geometrical Brownian motion with drift term which depends of the some hidden parameter.
Anthony Lock and Becky Shipley
Abstract
Anthony Lock will speak on "A Column Model of Moist Convection".
Muscle Contraction: impulsive interactions at low Reynold's number and connecting the microscopic with the macroscopic
17:00
Canonical bases of types of finite SU-rank
Abstract
I will speak about the CBP (canonical base property) for types of finite SU-rank. This property first appears in a paper by Pillay and Ziegler, who show that it holds for types of finite rank in differentially closed fields of characteristic 0, as well as in existentially closed difference fields. It is unknown whether this property holds for all finite rank types in supersimple theories. I will first recall the definition of a canonical base, and give some natural examples. I will then talk about a reduction of the problem (which allows one to extend the Pillay-Ziegler result to existentially closed fields of any characteristic), and finally derive some consequences of the CBP, in particular the UCBP, thus answering a question of Moosa and Pillay. If time permits, I will show an application of these results to difference
fields.
Dynamics of Vesicles: Experiments, Analytics, and Simulations:
Abstract
An overview of the experiments of Steinbergs group, Theory-and-models and comparison of the applicability of recent reduced models.
16:00
Mesh redistribution algorithms and error control for time-dependent PDEs
Abstract
Self adjusted meshes have important benefits approximating PDEs with solutions that exhibit nontrivial characteristics. When appropriately chosen, they lead to efficient, accurate and robust algorithms. Error control is also important, since appropriate analysis can provide guarantees on how accurate the approximate solution is through a posteriori estimates. Error control may lead to appropriate adaptive algorithms by identifying areas of large errors and adjusting the mesh accordingly. Error control and associated adaptive algorithms for important equations in Mathematical Physics is an open problem.
In this talk we consider the main structure of an algorithm which permits mesh redistribution with time and the nontrivial characteristics associated with it. We present improved algorithms and we discuss successful approaches towards error control for model problems (linear and nonlinear) of parabolic or hyperbolic type.
Degenerations of <2>-polarised K3 surfaces
Abstract
A -polarised K3 surface admits an embedding into weighted projective space defined by its polarisation. Let X be a family of such surfaces, then one can construct a projective model W of X such that the map from X to W realises this embedding on the general fibre. This talk considers what happens to W when we allow the fibres of the family X to degenerate.
On the Semisimplicity Problem for Group Rings
Abstract
The semisimplicity problem is the long-standing conjecture that the group algebra $KG$ of a $p'$-group $G$ over a field $K$ of characteristic $p\geqslant 0$ has zero Jacobson radical. We will discuss recent advances in connection with this problem.
16:00
Small cancellation complexes
Abstract
We will discuss a connection between small cancellation conditions and isoperimetric inequalities. Additionally we shall look at a useful construction connecting small cancellation complexes and cube complexes.
(HoRSe seminar) Hilbert schemes of threefolds: virtual motives, Hodge modules and deformed MacMahon formulae II
Abstract
I will talk about joint work with Dimca, respectively Behrend and Bryan, in which we refine the numerical DT-Behrend invariants of Hilbert schemes of threefolds by using vanishing cycle motives (a la Kontsevich-Soibelman) or mixed Hodge modules, leading to deformed MacMahon formulae.