Summation of Formal Power Series Through Iterated Laplace Integrals.
Über Abschnittslimitierbarkeit.
Zum Einzigkeitssatz in der Invariantentheorie meromorpher Differentialgleichungen.
Semi-formal theory and Stokes' phenomenon of non-linear meromorphic systems of ordinary differential equations
This article continues earlier work of the author on non-linear systems of ordinary differential equations, published in Asymptotic Analysis 15 (1997), MR no. 98g:34015b. There, a completely formal theory was presented, while here we are concerned with a semi-formal approach: Solutions of non-linear systems of ordinary meromorphic differential equations are represented as, in general divergent, power series in several free parameters. The coefficients, aside from an exponential polynomial, a general...
Summability of power series in several variables, with applications to singular perturbation problems and partial differential equations
Necessary and sufficient conditions for matrix summability methods to be stronger than multisummability
For general matrix summability methods, we find necessary and sufficient conditions for such methods to be stronger than multisummability. In a second part we show the existence of power series which are not multisummable but can be summed by a matrix method satisfying the conditions mentioned above
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