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DateSpeakerTitle & Abstract
Wed., Dec. 10
15-16 pm
Åsa Hirvonen
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titleClassification theory 'up to perturbation'

Classification theory is a branch of model theory that tries to
classify the models in a given class by finding various dimensions.
Concrete examples of such are the transcendence degree of an algebraically
closed field or the linear dimension of a vector space.

When turning to structures from analysis (e.g. Banach spaces, operators,
etc.) new phenomena arise. One is that things looks better if studied 'up
to perturbation'. In this talk I will talk about what happens when one
attempts classificatio theory 'up to perturbation': which model
theoretical methods work, which don't, which ones would I like to attain.

Nov. 25Henrik Kettunen
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titleElectromagnetics with negative material parameters

The Maxwell equations form the basis of the classical electromagnetic theory. In addition to these famous four equations, we need the constitutive relations, which connect the fields and flux densities to each other by the material parameters, permittivity and permeability. It is very natural to assume that these material parameters are in most cases positive. However, if we allow them to go negative, we face new exciting physical phenomena that have attracted mathematicians, physicists and engineers alike. For example, double-negative materials allow backward wave propagation and negative refraction enabling sub-wavelength focusing of a light beam. If only the electric permittivity is negative, such interfaces can support plasmonic resonances that are sub-wavelength oscillations of electron density excited by the incident light. Noble metals can manifest negative permittivity at visible and ultraviolet frequencies. However, the possibility of constructing double-negative materials has become closer to reality only recently alongside the research of artificial metamaterials.

Nov. 11Stefan Wagner
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titleJouko Mickelsson or: How I learned to stop worrying and love the gerbe

The word "gerbe" is an odd one-it is not a furry little animal, nor a hip slang word used to indicate your disrespect towards someone. In fact, it derives instead from a french word in common use and got absorbed by English language. The Oxford English dictonary gives "something resembling a sheaf of wheat" and "something resembling a sheaf" is quite close to the mathematical meaning of the word. In this talk I plan to give a short insight in the theory of gerbes and its connection to cohomology. 

Oct. 23Oleg Ivrii
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titleA personal journey through hyperbolic geometry

In this talk, I will discuss how I came to know and like hyperbolic geometry. I will discuss a few results which I think are absolutely striking such as Poincaré's reflection theorem and Mostow rigidity. Time permitting, I will say a few words about Sullivan's dictionary and discuss some parallel ideas in complex dynamics.

 Oct. 7

Ismael Rodrigo Bleyer
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titleDigital speech: an application of the dbl-RTLS method for solving GIF problem

"Digital Speech Processing" refers to the study of a speech signal. Namely, these signals are processed in a digital representation, as for example, synthesis, analysis, enhancement, compression and recognition may refers to this process.

In this talk we are interested on solving the core problem known as "Glottal Inverse Filtering" (GIF). Commonly this problem can be modelled by convolving a pressure function (input signal) with an impulse response function (filter). Our approach is done in a deterministic setup based on the dbl-RTLS (double regularised total least squares) approach introduced recently. Additionally we review briefly the methodology and we give the first numerical realisations, based on an alternating minimisation procedure.

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