Séminaire du 25 octobre 2010, 14h00: Alexandre
Sedoglavic, Laboratoire d'Informatique Fondamentale de
Lille.
* A geometric point of view on implicit systems of differential
algebraic equations*

We present some work done in relation with the ANR LEDA project.
Classically an implicit system of differential algebraic equations
defines a variety in a jet-space. Supposing that this variety is
smooth enough, one can define a direction field at any of its
regular points using its tangent plane and the
so-called *contact plane * at this point.
Differential algebraic equations (DAEs) are a general form of
differential equations that are not completely solvable for the
derivatives of all components of their states variables.
The talk presents the relationships between the above classical
framework and a class of DAEs occuring in practice. We show how an
explicit ODE equivalent to a given DAE can be found using some Lie
point symmetry of the associated variety in a jet-space.

Virginie Collette
Last modified: Mon Sep 20 14:24:06 CEST 2010