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Algebraic independence of the values of power series with unbounded coefficients. (English) Zbl 1432.11098

Summary: Many mathematicians have studied the algebraic independence over \(\mathbb{Q}\) of the values of gap series, and the values of lacunary series satisfying functional equations of Mahler type. In this paper, we give a new criterion for the algebraic independence over \(\mathbb{Q}\) of the values \(\sum^{\infty}_{n=0} t(n) \beta^{-n}\) for distinct sequences \((t(n))^{\infty}_{n=0}\) of nonnegative integers, where \(\beta\) is a fixed Pisot or Salem number. Our criterion is applicable to certain power series which are not lacunary. Moreover, our criterion does not use functional equations. Consequently, we deduce the algebraic independence of certain values \(\sum^{\infty}_{n=0} t_1 (n) \beta^{-n}, \ldots, \sum^{\infty}_{n=0} t_r( n) \beta^{-n}\) satisfying
\[ \lim_{\substack{n \rightarrow \infty \\ t_{i-1}(n) \ne 0}} \frac{t_i(n)}{t_{i-1}(n)^M} = \infty \quad (i=2, \dotsc, r) \]
for any positive real number \(M\).

MSC:

11J91 Transcendence theory of other special functions
11K16 Normal numbers, radix expansions, Pisot numbers, Salem numbers, good lattice points, etc.
11K60 Diophantine approximation in probabilistic number theory
11J85 Algebraic independence; Gel’fond’s method
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