Resurgent functions: examples and perspectives

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Maxim Kontsevich, Institut des Hautes Études Scientifiques

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Theory of resurgent functions was developed by Jean Écalle starting from early 80-ies.ÌýVery often in physics and mathematics we have an asymptotic expansion in small parameter which is divergentÌýbecause the coefficients have factorial growth anÌý∼ n! exp(O(n)). The property ofÌýresurgenceÌýmeans that the Borel transform ∑nÌýanζn/n! admits an endless analytic continuation, which allows to reconstruct the exact value of the original divergent series.

I will give some examples of resurgent series (classical special functions, Écalle-Voronin theory,Ìýheat kernel, WKB approximation), and propose some new viewpoints (Hodge structures of infinite rank, analytic wall-crossing structures).