The Membership Problem for Hypergeometric Sequences with Rational Parameters

We investigate the Membership Problem for hypergeometric sequences: given a hypergeometric sequence $\langle u_n \rangle_{n=0}^\infty$ of rational numbers and a target $t \in \mathbb{Q}$, decide whether $t$ occurs in the sequence. We show decidability of this problem under the assumption that in the defining recurrence $p(n)u_{n+1}=q(n)u_n$, the roots of the polynomials $p(x)$ and $q(x)$ are all rational numbers. Our proof relies on bounds on the density of primes in arithmetic progressions. We also observe a relationship between the decidability of the Membership problem (and variants) and the Rohrlich-Lang conjecture in transcendence theory. This work is in collaboration with Amaury Pouly, Mahsa Shirmohammadi and James Worrell. The full paper is available online: https: //arxiv. org/abs/2202. 07416

Authors

• Klara Nosan

Keywords

No keywords are indexed for this paper.