Bonjour,
ce mardi 15 novembre 2016 auront lieu 3 seminaires !
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À 10h30 en B107, Suzy Maddah nous parlera de : On Generalized Hypergeometric
Solutions of Linear Differential Systems of First Order.
Résumé : In this talk, we consider linear differential systems of first
order (equivalently linear differential equations of arbitrary order), and
we question whether they can be solved in terms of generalized
hypergeometric functions. This question is motivated by the many properties
of the latter which arise in physics and combinatorics. It has been tackled
in the literature for second-order differential equations, namely Bessel's,
Whittaker's, Kummer's, and Gauss's. We propose a new algorithm which
surpasses the restrictions on the dimension of the system, and equivalently
on the order of the equation. This is a joint work with Frédéric Chyzak.
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À 14h00 en B107, Samuel Petite nous parlera de : Restrictions sur le groupe
d'automates cellulaires préservant un sous-shift fixé.
Résumé : Un sous shift est un ensemble fermé de suites sur un alphabet fini,
invariant par décalage (le shift). L'ensemble des automates cellulaires
préservant ce sous shift est en général un groupe dénombrable compliqué.
Nous présenterons dans cet exposé un survol des différentes restrictions sur
ces groupes pour les sous-shift d'entropie nulle.
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À 15h15 en B107, Quoc Hoan Ngo nous parlera de : An interface between
physics and number theory.
Résumé : In this talk are studied the polylogarithms and the harmonic sums
at non-positive (i.e. weakly negative) indices. General results about these
objects in relation with Hopf algebras are provided. The technics are based
on the combinatorics of noncommmutative generating series relative to the
Hopf φ-shuffle algebra. Our work here will also propose a global process to
renormalize the divergent polyzetas. Finally, we will apply these ideas to
non-linear dynamical systems with singular inputs.
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A mardi,
Thierry
