Prof.
Erik Aurell
(KTH),
Mikko Alava
(HUT, Espoo, Finland)
15/05/2008, 09:00
Dr
Supriya Krishnamurthy
(SICS)
15/05/2008, 09:20
Overlay networks are application-level networks, or networks
of acquaintances, established on top of physical networks,
such as the Internet. Peer-to-Peer (P2P) systems are one
class of overlay networks, in which all nodes in the system
are equivalent and all tasks are carried out without the
presence of any central authority. Despite their relatively
short history, peer-to-peer overlays...
Prof.
Riccardo Zecchina
(Politecnico di Torino)
15/05/2008, 10:00
Given an undirected graph with positive weights on the
edges, the Minimum Weight Steiner Tree (MST) problem
consists in finding a connected subgraph of minimum weight
that contains a selected set of ``terminal'' vertices. Such
construction may require the inclusion of some non-terminal
nodes which are called Steiner nodes. Clearly, an optimal
sub-graph must be a tree. Solving MST is a...
Dr
Luca Dall'Asta
(Abdus Salam ICTP)
15/05/2008, 11:00
Many efforts have been devoted to characterize the onset of
congestion in communication networks. Numerical simulations
performed using complex routing protocols have revealed that
congestion always occurs as an effect of traffic increase,
but with specific features that strictly depend on the
local routing scheme. (For instance, the continuous or
discontinuous character of the...
Jeremy Stribling
(MIT CSAIL)
15/05/2008, 13:00
It is a challenge to build applications that need to share
data and are distributed across hundreds or thousands of
computers in a wide-area network (e.g., PlanetLab or on a
Grid). In order to cope with high latency, throughput
bottlenecks, and temporary failures, such applications
typically implement their own storage plan or use
special-purpose storage solutions (e.g., DISC,...
Danny Bickson
(The Hebrew University of Jerusalem)
15/05/2008, 14:00
The canonical linear-algebraic problem of solving a system
of linear equations arises in numerous contexts in the
mathematical sciences and engineering. In this talk, we
introduce an efficient Gaussian belief propagation (GaBP)
solver that does not involve direct matrix inversion. The
iterative nature of our approach allows for a distributed
message-passing implementation of the solution...
Dr
Dimos Dimarogonas
(KTH)
15/05/2008, 14:20
Multi-agent consensus problems where agents aim to attain a
common value of some quantity under limited communication
have received increasing attention recently, due to their
application in multi-vehicle and multi-robot systems, as
well as distributed estimation and filtering in networked
systems. In this talk we present two recent results on
consensus problems. The first part of the...
Prof.
Olav Tirkkonen
(TKK)
15/05/2008, 15:20
Prof.
Bernhard Mehlig
(Chalmers University of Technology)
15/05/2008, 16:40
Prof.
Massimo Vergassola
(Institut Pasteur)
16/05/2008, 09:00
Prof.
Elena Dubrova
(KTH)
16/05/2008, 10:00
Random Boolean Networks (RBNs) were introduced by Kaufmann
in 1969 in the context of gene expression and fitness
landscapes. They were applied to the problems of cell
differentiation, immune response, evolution, and neural
networks. They have also attracted the interest of
physicists due to their analogy with the disordered systems
studied in statistical mechanics, such as the mean...
Prof.
Joachim Krug
(University of Cologne)
16/05/2008, 10:20
The evolutionary search of a finite population in a rugged
fitness or energy landscape with many local optima is a
paradigmatic problem that connects evolutionary biology to
the statistical physics of disordered systems and computer
science. In this brief presentation I summarize the results
of two recent studies which addressed different aspects of
this problem. A detailed numerical...
Prof.
Haijun Zhou
(Chinese Academy of Sciences)
16/05/2008, 11:00
The mutual influence of structure and dynamical processes in
a complex networked system is an active yet challenging
research topic. In the present report we approach this
problem by studying a simple model system, namely the local
majority-rule (LMR) dynamics on an evolving network. We
first show analytically and by computer simulation that the
structure of the network can have a...
Prof.
Scott Kirkpatrick
(School of Engineering and CS, HUJI)
16/05/2008, 13:00
Statistical mechanics turned a corner with Mezard and
Zecchina's realization that its methods could be applied to
solve individual combinatorial problems as well as to
characterize the expected outcome of classes of problems.
But the methods, such as message passing or simulated
annealing, that stay closest to the physical analogies can
be extremely time-consuming and may not scale to...
Dr
Luis Lafuente
(MIT CBA)
16/05/2008, 14:00
Linear Programming can solve some unlikely problems, like
decoding parity check codes, sorting, and other things. A
lovely old theorem by Birkhoff and von Neumann distinguishes
the cases in which the solution is guaranteed to lie on the
integers 0 and 1. Unfortunately, this result fails to apply
to NP-Complete problems -- it guarantees to solve the 8
rooks problem, but not the 8...
Prof.
Ilkka Niemelä
(TKK)
16/05/2008, 15:00
Tools for solving the propositional satisfiability (SAT)
problem have advanced dramatically during the last ten years
and are now standardly used in industrial applications such
as hardware design verification and automatic test pattern
generation. SAT solvers are also becoming widely used
search engines in areas with challenging computation
problems such as automated planning,...
Prof.
John Hertz
(NORDITA)
16/05/2008, 16:00
We can learn something about how large neuronal networks
function from models of the spike pattern distributions
constructed from data. In our work, we do this for data
generated from simulated models of local cortical networks,
using the approach introduced by Schneidman et al, modeling
this distribution by an Ising model: P[S] =
Z^{-1}exp(½Σ_{ij}J_{ij}S_iS_j+Σ_i h_i S_i). To estimate...
Prof.
Heiko Rieger
(Universität des Saarlandes)
16/05/2008, 16:20
Targeted transport of vesicles, organelles and other types
of cargo is necessary for living cells to maintain their
complex internal structure. Molecular motors attached to
this cargo power the long-range traffic of cargo along
microtubules in a bidirectional way. The attachment of two
kinds of motors, one pulling towards the cell periphery and
one towards the cell center, lead to a...
Prof.
Neil Gershenfeld
(MIT CBA)
16/05/2008, 17:00
Computer Science has served to isolate programs (and
programmers) from knowledge of the underlying physical
mechanisms used for computation. However, in the limit in
which the number of computational and physical degrees of
freedom become equivalent it's no longer possible to
maintain this fiction. I will explore the benefits of
exposing rather than hiding the boundary between bits...
Prof.
Johan Håstad
(KTH)
17/05/2008, 09:00
Prof.
Pekka Orponen
(TKK)
17/05/2008, 10:20
We present a combinatorial method for the uniform sampling
of local energy minima in square and hexagonal 2D Ising spin
glass lattices. The method has been used to estimate the
number and energy distribution of local minima in lattices
of up to 2000 spins.
Dr
Ashish Sabharwal
(Cornell)
17/05/2008, 11:00
We consider the problem of estimating the model count
(number of solutions) of Boolean formulas, and present two
techniques that compute estimates of these counts, as well
as either lower or upper bounds with different trade-offs
between efficiency, bound quality, and correctness
guarantee. For lower bounds, we use a recent framework for
probabilistic correctness guarantees, and exploit...
Prof.
Alexander Hartmann
(University of Oldenburg)
17/05/2008, 13:00
Lenka Zdeborova
(U Paris-Sud)
17/05/2008, 14:00
We introduce the random `locked' constraint satisfaction
problems. When increasing the density of constraints, they
display a broad `clustered' phase in which the space of
solutions is divided into many isolated points. While the
phase diagram can be found easily, these problems, in their
clustered phase, are extremely challenging from the
algorithmic point of view: the best known...
Prof.
Florent Krzakala
(ESPCI, Paris)
17/05/2008, 14:20
In this talk, we will discuss (some) of the consequences of
the phase transitions that arise in random constraint
satisfaction problems, and present a simple strategy that
allows to understand why it is so easy to find solutions in
the clustered phase.
Dr
Petter Holme
(Coputational Biology)
17/05/2008, 16:00
In spite of advances in hospital treatment, hospitals
continue to be a breeding ground for several airborne
diseases and for diseases that are transmitted through
close contacts like SARS, methicillin-resistant
Staphylococcus aureus (MRSA), norovirus infections and
tuberculosis (TB). Here we extract contact networks for up
to 295,108 inpatients for durations up to two years from...
Prof.
Federico Ricci-Tersenghi
(Roma)
17/05/2008, 16:20
Prof.
Matteo Palassini
(Barcelona)
17/05/2008, 16:40
