Aims and Scope --
Our Sponsors --
Poster Download
School on Combinatorics, Automata and Number Theory - Liège June 2009
From
1st to 5th June 2009, the second edition of the summer
school CANT will be organized in Liège. The
first edition
was organized in May 2006 and gathered around 100 participants.
This time, we propose in Liège two joint events connected to
automata in the wide sense. During the week following this school will
be organized the
AutoMathA
conference (8-12 June 2009). The AutoMathA programme is a
five-year multidisciplinary programme (2005-2010), at the crossroads
of mathematics, theoretical computer science and applications, gathers
14 European countries. The goal of AutoMathA is to propose a set of
co-ordinated actions for advancing the theory of automata and for
increasing its application to challenging scientific problems. See
http://www.esf.org/automatha
for more details. See our sponsors
below.
Some of the slides are available
This CANT international school is aimed at presenting and developing recent
trends in Combinatorics, Automata Theory and Number Theory. In the
last decade, interest in Combinatorics on Words and in the the
relationships existing between Mathematics and Theoretical Computer
Science has grown constantly. As a matter of fact, a series of
international conferences as well as books are now devoted to these
specific topics. One of the leading idea behind our concept of
Combinatorics, Automata and Number Theory is to focus on the fruitful
interactions existing between these different fields.
The main
topics of this school are (4 hours and a half for each subject)
- Number representation and finite automata
- Factor complexity
- Tilings, substitutions and Rauzy fractals
- Block frequencies in infinite words and invariant measures
- Transcendence and Diophantine approximation
- Maximal products of matrices and the finiteness property
Note : A book (to appear in the Encyclopedia for Mathematics
and its Applications, Cambridge University Press) is in preparation
and will contain 10 chapters amongst them 6 corresponding to the
lectures given during the school.
This international school is aimed at presenting and developing recent
trends in Combinatorics, Automata Theory and Number Theory. On the one
hand, the newest results in these areas shall benefit from a synthetic
exposition, and on the other hand, emphasis on the connections
existing between the main topics of the school will be sought. To
reach these complementary goals, high quality lecturers of
international recognition have been selected. Due to their scientific
and pedagogical capabilities, we hope that they will attract a wide
audience including Ph.D. students, young researchers as well as more
mature researchers. They have been asked to convey in their lectures
state-of-the-art results, open problems and main issues in their
individual field of expertise. We hope that this joint event will
bring synergy to the entire community by bringing together researchers
working in a specific domain but also by facilitating the interactions
amongst researchers working in close and related areas of mathematics.
It is a difficult task to briefly present the main subjects of the
school, however they can be succinctly explained as
follows. Combinatorics, and more specifically combinatorics on
words, deals with problems that can be stated in a noncommutative
monoid such as subword complexity of finite or infinite words,
construction and properties of infinite words, block frequencies,
unavoidable regularities or patterns,.... A fruitful use of word
combinatorics is its contribution to the study of dynamical systems,
such as illustrated by the interplay between notions like minimality
and uniform recurrence, or unique ergodicity and uniform
frequencies. For instance, the coding of orbits and trajectories by
words, constitutes the basis of symbolic dynamical systems: A
historical example dating back to 1921, is the study by H. M. Morse
of recurrent geodesics on a surface with negative curvature. As an
other example, these similar ideas are found in connection with the
Word Problem in group theory. Moreover the use of combinatorics is
sought in the analysis of algorithms, initiated by D. E. Knuth, and
which greatly relies on number theory, asymptotic methods and
computer algebra. When considering some numeration system, any
integer can be represented as a finite word over an alphabet of
digits. This simple observation leads to the study of the
relationship between the arithmetical properties of the integers and
the syntactical properties of the corresponding representations. One
of the deepest results in this direction is given by the celebrated
Cobham's theorem. Surprisingly, a recent extention of this latter
result to the complex numbers leads to the famous Four Exponentials
Conjecture. This is just one example of the fruitful relationship
between formal language theory (including the theory of automata)
and number theory. Other examples are given by the study of digital
functions, automatic sequences and the transcendence of formal power
series, the Rauzy fractal and discrepancy problems and by the
representation of real numbers in various numeration systems. This
latter problem is in particular related to Diophantine analysis or
approximations of real numbers to algebraic numbers, which has
recently enjoyed striking developments through a fruitful interplay
between Diophantine approximation and combinatorics on words. On the
other hand, we have to keep in mind that both combinatorics on words
and theory of formal languages have important applications and
interactions in computer science and physics. To cite just a few:
dynamical systems and control theory, study and models of
quasicrystals, aperiodic order and quasiperiodic tilings,
bioinformatics and DNA analysis, theory of parsing, algorithmic
verification of large systems, coding theory, discrete geometry and
more precisely discretization for computer graphics on a raster
display,....Let us quote as a particularly striking example the
problem of maximizing products of matrices taken from a finite
set. Indeed the joint spectral radius is of great interest in a
number of diverse applications, including word combinatorics.