Effective algebraic independence of values of E-functions.

E-functions are entire functions with algebraic Taylor coefficients satisfying certain arithmetic conditions, and which are also solutions of linear differential equations with coefficients in Q ¯ (z) . They were introduced by Siegel (Über einige Anwendungen diophantischer Approximationen, vol. 1. S. Abhandlungen Akad, Berlin, 1929) to generalize the Diophantine properties of the exponential and the Bessel functions. The Siegel–Shidlovskii theorem (1956) deals with the algebraic (in)dependence of values at algebraic points of E-functions solutions of a differential system. In this paper, we present an algorithm to perform the following three tasks. Given as inputs some E-functions F 1 (z) ,..., F p (z) , (1) it computes a system of generators of the ideal of polynomial relations between F 1 (z) ,..., F p (z) with coefficients in Q ¯ (z) ; (2) given any α ∈ Q ¯ , it computes a system of generators of the ideal of polynomial relations between the values F 1 (α) ,..., F p (α) with coefficients in Q ¯ ; (3) if F 1 (z) ,..., F p (z) are algebraically independent over Q ¯ (z) , it determines the finite set of all α ∈ Q ¯ such that the values F 1 (α) ,..., F p (α) are algebraically dependent over Q ¯ . The existence of this algorithm relies on a variant of the Hrushovski–Feng algorithm (to compute polynomial relations between solutions of differential systems) and on Beukers’ lifting theorem (an optimal refinement of the Nesterenko–Shidlovskii theorem) in order to reduce these problems to an effective elimination procedure in multivariate polynomial rings. The latter is then performed using Gröbnerbasis. [ABSTRACT FROM AUTHOR]