Is there a computable upper bound for the height of a solution of a Diophantine equation with a unique solution in positive integers?

摘要

Let Bn = {xi · xj = xk : i, j, k ∈ {1, . . . , n}} ∪ {xi + 1 = xk : i, k ∈ {1, . . . , n}} denote the system of equations in the variables x1, . . . , xn. For a positive integer n, let _(n) denote the smallest positive integer b such that for each system of equations S ? Bn with a unique solution in positive integers x1, . . . , xn, this solution belongs to [1, b]n. Let g(1) = 1, and let g(n + 1) = 22g(n) for every positive integer n. We conjecture that ξ (n) 6 g(2n) for every positive integer n. We prove: (1) the function ξ : N {0} → N {0} is computable in the limit; (2) if a function f : N {0} → N {0} has a single-fold Diophantine representation, then there exists a positive integer m such that f (n) ξ (n) for every integer n m; (3) the conjecture implies that there exists an algorithm which takes as input a Diophantine equation D(x1, . . . , xp) = 0 and returns a positive integer d with the following property: for every positive integers a1, . . . , ap, if the tuple (a1, . . . , ap) solely solves the equation D(x1, . . . , xp) = 0 in positive integers, then a1, . . . , ap 6 d; (4) the conjecture implies that if a set M ? N has a single-fold Diophantine representation, then M is computable; (5) for every integer n 9, the inequality ξ (n) (22n?5 ? 1)2n?5 + 1 implies that 22n?5 + 1 is composite.