Concours d'admission à l'École normale supérieure
Conjugacy and disconjugacy criteria are established for the equation where is a locally summable function.
In this article we investigate the question [of] how meromorphic differential equations can be simplified by meromorphic equivalence. In the case of equations of block size 1, which generalizes the case of distinct eigenvalues, we identify a class of equations which are simplest possible in the sense that they carry the smallest number of parameters whithin their equivalence classes. We also discuss conditions under which individual equations can be simplified. Particular attention is paid to the...
The problem of continuous dependence for inverses of fundamental matrices in the case when uniform convergence is violated is presented here.
We present here the problem of continuous dependence for generalized linear ordinary differential equations in the case when uniform convergence is violated. This work continues research of M. Ashordia (1993) and M. Tvrdý (2002).
In the paper, we unify and extend some basic properties for linear control systems as they appear in the continuous and discrete cases. In particular, we examine controllability, reachability, and observability for time-invariant systems and establish a duality principle.
In this paper we present an algebraic approach that describes the structure of analytic objects in a unified manner in the case when their transformations satisfy certain conditions of categorical character. We demonstrate this approach on examples of functional, differential, and functional differential equations.