arXiv subjects

Andrew Scoones

Publications and source records attributed to Andrew Scoones.

5 recordsLinked to original sources

arXiv2025

On the growth of hypergeometric sequences

Hypergeometric sequences obey first-order linear recurrence relations with polynomial coefficients and are commonplace throughout the mathematical and computational sciences. For certain classes of hypergeometric sequences, we prove linear growth estimates on their Weil heights. We give an application of our effective results towards the Membership Problem from Computer Science. Recall that Membership asks to procedurally determine whether a specified target is an element of a given recurrence sequence.

math.NT↗

arXiv2024

Reachability for Multi-Priced Timed Automata with Positive and Negative Rates

Multi-priced timed automata (MPTA) are timed automata with observer variables whose derivatives can change from one location to another. Observers are write-only variables, that is, they do not affect the control flow of the automaton; thus MPTA lie between timed and hybrid automata in expressiveness. Previous work considered observers with non-negative slope in every location. In this paper we treat observers that have both positive and negative rates. Our main result is an algorithm to decide a gap version of the reachability problem for this variant of MPTA. We translate the gap reachability problem into a gap satisfiability problem for mixed integer-real systems of nonlinear constraints. Our main technical contribution -- a result of independent interest -- is a procedure to solve such contraints via a combination of branch-and-bound and relaxation-and-rounding.

cs.FL↗

arXiv2024

Transcendence for Pisot Morphic Words over an Algebraic Base

It is known that for a uniform morphic sequence $\boldsymbol u = \langle u_n\rangle_{n=0}^\infty$ and an algebraic number $\beta$ such that $|\beta|>1$, the number $[\![\boldsymbol{u} ]\!]_\beta:=\sum_{n=0}^\infty \frac{u_n}{\beta^n}$ either lies in $\mathbb Q(\beta)$ or is transcendental. In this paper we show a similar rational-transcendental dichotomy for sequences defined by irreducible Pisot morphisms. Subject to the Pisot conjecture (an irreducible Pisot morphism has pure discrete spectrum), we generalise the latter result to arbitrary finite alphabets. In certain cases we are able to show transcendence of $[\![\boldsymbol{u}]\!]_{\beta}$ outright. In particular, for $k\geq 2$, if $\boldsymbol u$ is the $k$-bonacci word then $[\![\boldsymbol{u}]\!]_{\beta}$ is transcendental.

math.NT↗

arXiv2024

Effective Results in The Metric Theory of Quantitative Diophantine Approximation

Many results related to quantitative problems in the metric theory of Diophantine approximation are asymptotic, such as the number of rational solutions to certain inequalities grows with the same rate almost everywhere modulo an asymptotic error term. The error term incorporates an implicit constant that varies from one point to another. This means that applications of these results does not give concrete bounds when applied to, say a finite sum, or when applied to counting the number of solutions up to a finite point for a given inequality. This paper addresses this problem and makes the tools and their results effective, by making the implicit constant explicit outside of an exceptional subset of Lebesgue measure at most $δ>0$, an arbitrarily small constant chosen in advance. We deduce from this the fully effective results for Schmidt's Theorem, quantitative Koukoulopoulos-Maynard Theorem and quantitative results on $M_{0}$-sets; we also provide effective results regarding statistics of normal numbers and strong law of large numbers.

math.NT↗

arXiv2022

On the $abc$ Conjecture in Algebraic Number Fields

While currently the $abc$ conjecture and work towards it remains open or is disputed, at the same time much work has been done on weaker versions, as well as on its generalisation to number fields. Given integers satisfying $a+b=c$, Stewart and Yu were able to give an exponential bound for $\max(a,\,b,\,c)$ in terms of the radical over the integers, while Györy was able to give an exponential bound in the algebraic number field case for the projective height $H_{K}(a,\,b,\,c)$ in terms of the radical for algebraic numbers. We generalise Stewart and Yu's method to give an improvement on Györy's bound for algebraic integers. Finally, we will give an application to the effective Skolem-Mahler-Lech problem. Of importance is to note that, given some conditions, we obtain a sub-exponential bound for $\log H_{L}(a,\,b,\,c)$. We use these results to give an improvement on a result by Lagarias and Soundararajan. At the final stages of preparation, we were made aware that a similar result to our main theorem has been obtained independently by Györy, using different methods.

math.NT↗