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[#P27] Hilbert's tenth problem over the rationals

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Problem. Does there exist an algorithm which, given any polynomial \(f\in\mathbb{Z}[x_1,\ldots,x_n]\), decides whether the equation \(f(x_1,\ldots,x_n)=0\) has a solution in \(\mathbb{Q}^n\)?

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1Context

The corresponding problem over the integers is undecidable. Replacing integers with rational numbers changes the problem enough that its decidability remains unknown.

2Remarks

Remark 1. A decision algorithm must halt on every input and answer correctly whether a rational solution exists.

Remark 2. A multivariable polynomial equation has a rational solution when rational values for all variables make the polynomial equal to zero.

3What counts as a solution

  • Give and prove correct a terminating algorithm for rational solvability of every integer-coefficient polynomial equation, or prove that no such algorithm exists.

1Status

Saved packet · July 31, 2026

What counts as a solution

Saved packet status (Dated status and exact unresolved remainder). Unresolved in this packet after the dated source check. Strongest checked result: Koenigsmann gives a universal first-order definition of Z in Q and proves that the universal-existential theory of Q is undecidable. The purely existential decision problem asked by Hilbert's tenth problem over Q remains open. Exact unresolved remainder: Give a terminating algorithm deciding rational solvability of every integer-coefficient polynomial equation, or prove that no such algorithm exists.[2][1]

1Packet records

2 records

Notes and companion material

Original intake status. The cited survey identifies Hilbert's tenth problem over Q as unresolved. The source and public status were checked on 2026-07-31. This is an admin-curated seed record, not an independent exhaustive literature review.

  • Undecidability over the integers does not decide the rational case. Many subrings and conditional cases are known.

Recorded example 1. The equation x^2 + y^2 = 1 has rational solutions, including x = 3/5 and y = 4/5.

Computational notes

  • Searching rational points by bounded height can find solutions but cannot certify their absence in general.

2See also

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Plain text
“Hilbert's tenth problem over the rationals.” TheoremDB. P27. Problem statement; statement text SHA-256 1f57419ef7e3f9fd2ff1bb4edd2a64a148e558c6dc5626746a3c270f9fadb7cf. https://theoremdb.org/statement/?ref=P27
BibTeX
@misc{theoremdb-problem-1f57419ef7e3f9fd2ff1bb4edd2a64a148e558c6dc5626746a3c270f9fadb7cf,
  title = {{Hilbert's tenth problem over the rationals}},
  howpublished = {TheoremDB},
  note = {Problem statement; statement text SHA-256 1f57419ef7e3f9fd2ff1bb4edd2a64a148e558c6dc5626746a3c270f9fadb7cf},
  url = {https://theoremdb.org/statement/?ref=P27}
}

This problem includes 2 records joined by 2 typed links, sourced from arxiv.org[1], current as of July 31, 2026.

1References

  1. Packet source. Sylvy Anscombe, Valentijn Karemaker, Zeynep Kisakürek, Vlerë Mehmeti, Margherita Pagano, and Laura Paladino, “A survey of local-global methods for Hilbert's Tenth Problem”. arXiv:2309.14987 (2023). Sylvy Anscombe et al., arXiv:2309.14987, abstract and introduction. ↗preprint · primary source · arXiv:2309.14987, checked 2026-07-31 · checked 2026-07-31Source use: original summary.The cited survey identifies Hilbert's tenth problem over Q as unresolved. The source and public status were checked on 2026-07-22. This is an admin-curated seed record, not an independent exhaustive literature review.Also cited at abstract and introduction.Also cited at Editorial research route recorded 2026-07-31.Source used to formulate or check the problem record.Source used to assess the problem's recorded status.States the exact Q-decidability problem as open and summarizes current local-global methods.Source named by the research packet.
  2. Jochen Koenigsmann, “Defining \mathbb Z in \mathbb Q”. Annals of Mathematics (2016), 73-93. DOI 10.4007/annals.2016.183.1.2. Theorem 1 and Corollary 3 on pages 74-75. ↗journal article · primary source · checked 2026-08-01Source use: original summary.Universally defines Z inside Q and proves universal-existential undecidability without settling the purely existential theory.

An original CC0 restatement prepared by TheoremDB maintainers.

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