Prezados colegas,
Semana que vem teremos, dentro do nosso grupo de pesquisa Lolita e do nosso
projeto CAPES
AmSud, duas palestras super interessantes: dos Prof. Catuscia Palamidessi
(INRIA Saclay) e Frank Valencia (CNRS).
Ambas serão no anfiteatro A do CCET, 17h. A da Catuscia terça dia 2/05 e a
do Frank quinta dia
4/05. Conforme solicitado a eles, ambos vão fazer apresentações de caráter
geral.
Para quem estiver por perto, a presença é super bem vinda!!!
Abraços, Elaine & Carlos Olarte.
****
02/04 17h anfiteatro A CCET
Title: Generalized differential privacy and applications to location
privacy
Speaker: Catuscia Palamidessi (INRIA Saclay, France)
Abstract:
Differential Privacy (DP) is one of the most successful approaches to
prevent
disclosure of private information in statistical databases. It provides a
formal privacy
guarantee, ensuring that sensitive information relative to individuals
cannot be
easily inferred by disclosing answers to aggregate queries. If two
databases are
adjacent, i.e. differ only for an individual, then the query should not
allow
to tell them apart by more than a certain factor. This induces a bound also
on
the distinguishability of two generic databases, which is determined by
their
distance on the Hamming graph of the adjacency relation.
In this talk we lift the restriction on the adjacency relation and we
explore the implications of DP
when the indistinguishability requirement depends on an arbitrary notion of
distance. We show that
we can naturally express, in this way, (protection against) privacy threats
that cannot be
represented with the standard notion, leading to new applications of the DP
framework. We give
intuitive characterizations of these
threats in terms of Bayesian adversaries, which generalize two
interpretations
of (standard) differential privacy from the literature. We revisit the
well-known results in the
literature of differential privacy stating that universally optimal
mechanisms exist only for counting
queries. We show that, in our extended setting, universally optimal
mechanisms exist for other
queries too, notably sum, average, and percentile queries.
Finally, we explore an application of our generalized DP to the case of
location privacy. In this
case, the domain consists of the locations on a map and the distance is the
geographical distance.
This instance of the property, that we call geo-indistinguishability, is a
formal notion of privacy for
location-based systems
that protects the user's exact location, while allowing approximate
information
-- typically needed to obtain a certain desired service -- to be released.
We describe how to use our mechanism to enhance LBS applications with
geo-indistinguishability guarantees without compromising the quality of the
application results. It turns out that, among the known mechanisms
independent of the prior, our
mechanism offers the best privacy guarantees. Finally we present a tool,
Location Guard, based on
our framework, that has become quite popular also among the general public.
***
04/04 17h anfiteatro A CCET
Title: An Introduction to the Theory of Concurrent Systems.
Speaker: Frank Valencia (CNRS & LIX, Ecole Polytechnique de Paris,
Universidad Javeriana Cali)
Abstract:
Several modern computational systems consist of multiple processes
computing concurrently,
possibly interacting among each other. This covers a vast variety of
systems which nowadays, due
to technological advances such as the Internet and mobile computing, most
people can easily
relate to. Traditional mathematical models of (sequential) computation
based on functions from
inputs to outputs no longer apply. The crux is that concurrent computation,
e.g., in a reactive
system, is seldom expected to terminate and it involves constant
interaction with the environment.
Concurrency Theory, and in particular process calculi, pioneered by Hoare
and Milner, among
others, is a branch of the theory of computation dealing with concurrent
computation. Process
calculi treat processes much like the lambda-calculus treats computable
functions. They provide a
language in which the structure of term represents the structure of
processes together with an
operational semantics to represent computational steps.
In this talk I will give a brief introduction to concurrency theory. I will
start from the classical theory
of automata and argue that it is not suitable for reasoning about
concurrent behavior. I will then
introduce bisimilarity, perhaps the most fundamental equivalence from
concurrency theory. I will
also describe one of the most representative process calculi for concurrent
behaviour CCS.
--
Elaine.
-------------------------------------------------
Elaine Pimentel - DMAT/UFRN
Address: Departamento de Matemática
Universidade Federal do Rio Grande do Norte
Campus Universitário - Av. Senador Salgado Filho, s/nº
Lagoa Nova, CEP: 59.078-970 - Natal - RN
Phone: +55 84 3215-3820
http://sites.google.com/site/elainepimentel/
Lattes: http://lattes.cnpq.br/3298246411086415
--------------------------------------------------------
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