## Well-behaved convolution averages and the non-accumulation theorem for limit-cycles.(English)Zbl 0857.34009

Braaksma, B. L. J. (ed.) et al., The Stokes phenomenon and Hilbert’s 16th problem. Proceedings of the workshop, Groningen, The Netherlands, May 31-June 3, 1995. Singapore: World Scientific. 71-101 (1996).
Summary: This expository paper introduces several uniformizing averages, which are serviceable in resummation theory because they manage to reconcile three essential, but at first sight quite conflicting demands: respecting convolution; preserving realness; reproducing latteral growth. Their potential range of application covers most situations characterized by a combination of (1) nonlinearity; (2) divergence, (3) realness. We sketch three typical applications, the last of which leads to a marginal, yet significant simplification of the constructive (i.e. resummation-theoretical) proof of the non-accumulation theorem for the limit-cycles of a real-analytic vector field on $$\mathbb{R}^2$$.
For the entire collection see [Zbl 0846.00026].

### MSC:

 34M99 Ordinary differential equations in the complex domain 32S05 Local complex singularities 32S65 Singularities of holomorphic vector fields and foliations 34C05 Topological structure of integral curves, singular points, limit cycles of ordinary differential equations 40A99 Convergence and divergence of infinite limiting processes 40H05 Functional analytic methods in summability 53B99 Local differential geometry 37-XX Dynamical systems and ergodic theory 60G15 Gaussian processes 60J60 Diffusion processes 60J65 Brownian motion