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Let be irrational and . Are there positive integers such that
Let be irrational and . Are there positive integers such that
Source: erdosproblems.com/496
An accepted solution exists. The statement is true.
The site, accessed 2026-09-04 and 2026-10-07, labels the problem PROVED and credits the proof to Margulis [Ma89]. That label describes the corrected Statement, which Margulis's theorem settles; the result is recorded as an accepted full claim with the site's curator as reviewer. Alexeev's Lean disproof of the site's wording is rejected, since it answers the site's wording, not the corrected statement.
The site's wording fails at every negative irrational : for
positive integers the quantity is ,
so and admit no triple. The failure covers half
the parameter's domain, so it is a failure of setting, not of range. The
change replaces "" by ""; nothing else changes.
The evidence is the setting the site names: its commentary calls the problem
originally a conjecture of Oppenheim and credits the proof to Margulis [Ma89],
and Margulis states the conjecture he proves for real nondegenerate indefinite
quadratic forms in at least three variables (Banach Center Publ. 23 (1989), p.
399, §1 and Theorem 1; §1 calls it Davenport's conjecture, and its footnote 1
credits the case of at least five variables to Oppenheim, Ann. of Math. 32
(1931), 271--288). The form is indefinite exactly when
and positive definite when , so the corrected Statement
is the ternary case of that conjecture with the coordinates made positive; the
form follows from the setting, not from the result that settles it. The site's
credit to Oppenheim and Margulis corroborates Margulis's statement of the
conjecture. The correction does not rest on Oppenheim's 1931 paper or on the
Oslo chapter the site cites as [Ma89]. The sign is already unstated in Erdős's
question of 1961 (p. 239), which asks about every irrational in
integers with no positivity or nonzero condition; there the zero triple
answers the negative case trivially, and the site's requirement of positive
integers turns that case into a failure. One result answers the site's wording
(every irrational ), not the corrected Statement (), so it
does not count toward the problem's standing. A Lean development
Erdos496.lean in Boris Alexeev's repository, added on 2026-08-21 with Codex
and GPT-5.6 Sol as formal authors (file at a pinned
commit),
proves the negation of the site's wording at ,
(not_erdos_496); it is recorded as
a rejected claim page (Alexeev, 2026).
The page's standing judges the corrected Statement.