On the Relationship Between Matiyasevich's and Smorynski's Theorems

Agnieszka Peszek, University of Agriculture, Faculty of Production and Power Engineering, Balicka 116B, 30-149 Krakow, Poland, Apoloniusz Tyszka, University of Agriculture, Faculty of Production and Power Engineering, Balicka 116B, 30-149 Krakow, Poland
2019 Scientific Annals of Computer Science
Yuri Matiyasevich's theorem states that the set of all Diophantine equations which have a solution in non-negative integers is not recursive. Craig Smoryński's theorem states that the set of all Diophantine equations which have at most finitely many solutions in non-negative integers is not recursively enumerable. Let R be a subring of Q with or without 1. By H_10(R), we denote the problem of whether there exists an algorithm which for any given Diophantine equation with integer coefficients,
more » ... ger coefficients, can decide whether or not the equation has a solution in R. We prove that a positive solution to H_10(R) implies that the set of all Diophantine equations with a finite number of solutions in R is recursively enumerable. We show the converse implication for every infinite set R ⊆ Q such that there exist computable functions τ_1,τ_2:N → Z which satisfy (∀ n ∈ N τ_2(n) ≠ 0) ∧ (τ_1(n)/τ_2(n): n ∈ N=R). This implication for R=N guarantees that Smoryński's theorem follows from Matiyasevich's theorem. Harvey Friedman conjectures that the set of all polynomials of several variables with integer coefficients that have a rational solution is not recursive. Harvey Friedman conjectures that the set of all polynomials of several variables with integer coefficients that have only finitely many rational solutions is not recursively enumerable. These conjectures are equivalent by our results for R=Q.