Esta página lista seminários (de investigação, expositórios, de alunos,...) num período configurável.
On Nonlocal -algebras of Bergman Type Operators.
Yuri Karlovich, Universidad Autónoma del Estado de Morelos, México and CEAF, IST.
The talk is devoted to the Fredholm study of -algebras of
Bergman type operators with piecewise continuous coefficients and
commutative groups of conformal mappings of a bounded simply
connected plane domain onto itself.
An overview of the E91 protocol.
Arnaldo Gouveia, SQIG - IT.
In the current Quantum Key Distribution (QKD) proposals it is
possible to generate a secret key and distribute it with the
involved parties separated in physical terms. This possibility
opens the possibility of structuring a a solution to the the
classical cryptography problem of key distribution with reduced
interaction among involved parties. Among other proposals to adress
this issue is the Eckert 91 protocol wich will be in scope in this
report. Proposed in 1991 by A. Eckert it is an entanglement based
protocol. The security assurance of entanglement based protocols is
based on impossibility of an eavesdropper has to clone a message
without destroying it. As such the receiver has the possibility to
detect eavesdropping and this is a major advantage of this type of
protocols. In the end the a security proof will be described.
Dualidades naturais em 50 minutos.
Maria João Gouveia, DM-UL / CAUL.
A dualidade de Pontryagin, estabelecida em 1934 para a variedade
dos grupos abelianos, e a dualidade de Stone, estabelecida em 1936
para a variedade das álgebras de Boole, são referências
obrigatórias quando se remonta às origens da teoria das
dualidades naturais. No entanto, é apenas nos anos 70 que surge um
maior impulso, com o aparecimento da dualidade de Priestley, para
os reticulados distributivos, e da dualidade de
Hofmann-Mislove-Stralka para semi-reticulados. O trabalho de Davey
e Werner, bem como o de Clark e Krauss, nos anos 80, abriram
caminho ao desenvolvimento de toda uma teoria que foi conquistando
o seu próprio espaço no seio da Álgebra. Neste seminário
faremos uma breve incursão pela teoria das dualidades naturais,
apresentando alguns dos resultados mais relevantes e referindo
algumas das áreas de investigação, como por exemplo a das
extensões canónicas de álgebras com reduto de reticulado, onde
as dualidades e as suas técnicas são utilizadas.
Holographic Entanglement Entropy and Its Applications.
Tadashi Takayanagi.
Video talk by Tadashi Takayanagi @ PI 2011 (1h 13min)
Vídeo: http://pirsa.org/11040059/
A anunciar.
Michele Cirafici, CAMGSD.
Gluing formulas for determinants of Dolbeault laplacians on Riemann
surfaces.
Richard Wentworth, University of Maryland .
We present gluing formulas for zeta regularized determinants of
Dolbeault laplacians on Riemann surfaces. These are expressed in
terms of determinants of associated operators on surfaces with
boundary satisfying local elliptic boundary conditions. The
conditions are defined using the additional structure of a framing,
or trivialization of the bundle near the boundary. An application
to the computation of bosonization constants follows directly from
these formulas.
Topology of representation varieties of surface groups.
Richard Wentworth, University of Maryland.
This will be a survey talk on some aspects of the geometry and
topology of moduli spaces of representations of surface groups into
Lie groups. I will discuss recent generalizations of the techniques
of Atiyah and Bott on equivariant Morse theory. These extend
results on stable bundles to Higgs bundles and associated moduli
spaces, which correspond to representation varieties into
noncompact Lie groups.
Partially funded by LARSyS through
CAMGSD.
A characterization of computable analysis on unbounded domains
using differential equations.
Manuel Campagnolo, ISA - TU Lisbon / SQIG - IT.
The functions of computable analysis are defined by enhancing
normal Turing machines to deal with real number inputs. One can
consider characterizations of these functions using function
algebras, known as real recursive functions. Since there are
numerous incompatible models of computation over the reals, it is
interesting to find that the two very different models we consider
can be set up to yield exactly the same functions. Bournez and
Hainry used a function algebra to characterize computable analysis,
restricted to the twice continuously differentiable functions with
compact domains. Campagnolo and Ojakian found a different (and
apparently more natural) function algebra that also yields
computable analysis, with the same restriction. In this talk I will
describe an improvement of earlier work, finding three function
algebras characterizing computable analysis, removing the
restriction to twice continuously differentiable functions and
allowing unbounded domains. One of these function algebras is built
upon the widely studied real primitive recursive functions.
Furthermore, the proof uses the previously developed method of
approximation, whose applicability is further evidenced by those
results. This talk reports on joint work with Kerry Ojakian.
A anunciar.
Pietro Grassi, Alessandria.
Hybrid systems.
David Henriques, CMU and SQIG-Instituto de Telecomunicações.
A anunciar.
João Gomes, Faculdade de Ciências, Universidade do Porto.
Non-computability and financial markets.
Daniel Graça, U Algarve / SQIG-Instituto de Telecomunicações.
Tight-frame Approach for Image Processing.
Raymond Chan, The Chinese University of Hong Kong.
In many practical problems in image processing, the observed
data sets are often incomplete in the sense that features of
interest in the image are missing partially or corrupted by noise.
The recovery of missing data from incomplete data is an essential
part of any image processing procedures whether the final image is
utilized for visual interpretation or for automatic analysis. In
this talk, we present our tight-frame algorithm for missing data
recovery. Tight-frames are extension of wavelets. They generalize
orthonormal wavelet systems and give more flexibility in filter
designs. We begin our talk with an introduction of tight-frames.
Then we illustrate how to apply the idea to different image
processing applications such as inpainting, impulse noise removal,
super-resolution image reconstruction and video enhancement.
Joint work with X. M. Yuan (Hong Kong Baptist University) and J.
F. Yang and M. Tao (Nanking University).
Statistical Model Checking for Markov Decision Processes.
David Henriques, CMU and SQIG-Instituto de Telecomunicações.
Insert session title.
Sumio Yamada, Tohoku University, Japan.
Generalized Heisenberg algebra and coherent states.
Yassine Hassouni, Faculty of Sciences of Rabat.
A review on generalized Heisenberg Algebra (GHA) is given. A way to
construct a coherent states on GHA is described. We treat with one
example: a particular physical system. We conclude by giving a
method of quantization through coherent states.
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