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21 votes
1 answer
1k views

Is "almost-solvability" of Diophantine equations decidable?

Say that a Diophantine equation is almost-satisfiable iff for each $n\in\mathbb{N}$ it has a solution mod $n$. Trivially genuine satisfiability over $\mathbb{N}$ implies almost-satisfiability, but the ...
Noah Schweber's user avatar
6 votes
1 answer
334 views

Given some recursive function, can we effectively associate it a polynomial as in the DPRM theorem?

I'm interested in the following assertion about the Davis-Putnam-Robinson-Matijasevich theorem Given a recursive function $f:\mathbb{N}\rightarrow\mathbb{N}$, i.e. its index, we can effectively get ...
Niconar's user avatar
  • 75
7 votes
0 answers
274 views

Is decidability reducible to unique decidability (perhaps in multilinear polynomial situations)?

Given a Diophantine equation it is not decidable if it has integer solution. I. Is there a Diophantine set $\mathcal D_{unique}$ satisfying the properties every member in $\mathcal D_{unique}$ is a ...
Turbo's user avatar
  • 13.9k
3 votes
0 answers
116 views

Variation in decidability of diophantine equations with field extension

Let $O_k$ be the ring of integers in a subfield $k$ of $\overline{\mathbb{Q}}$. Let's call an equation $p(x_1, \dots, x_n) = 0$ where $p$ is a polynomial in $n$-variables $x_1, \dots, x_n$ with ...
Fanta's user avatar
  • 31
5 votes
0 answers
356 views

minimum size of undecidable quadratic diophantine problems

According to Matiyasevich, the existence of integer solutions of systems of polynomial equations with integer coefficients is undecidable. By introducing additional variables substituting factors of ...
Arnold Neumaier's user avatar