Erdős problem 987
Clunie [Cl67] proved that there exists an infinite sequence on the unit circle with for all . Translating , the natural domain of is the half-open unit interval , matching the original [Er64b]/[Cl67] statement (any unit complex number is allowed, including , i.e. ).
Sources
FormalConjectures/ErdosProblems/
987.lean
Retained formal statement
Liu [Li69] showed that, for any , infinitely often under the additional assumption that there are only a finite number of distinct points. Clunie observed in the Mathscinet review of [Li69] that under this assumption in fact infinitely often (the version stated here).
∀ (x : ℕ → ℝ), (∀ (j : ℕ), x j ∈ Set.Ioo 0 1) → (Set.range x).Finite → ∃ᶠ (k : ℕ) in Filter.atTop, Erdos987.A x k = ⊤