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Erdős problem 1119

Let m\mathfrak{m} be an infinite cardinal with 0<m<c=20\aleph_0 < \mathfrak{m} < \mathfrak{c} = 2^{\aleph_0}. Let {fα}\{f_\alpha\} be a family of entire functions such that, for every z0Cz_0 \in \mathbb{C}, there are at most m\mathfrak{m} distinct values of fα(z0)f_\alpha(z_0). Must {fα}\{f_\alpha\} have cardinality at most m\mathfrak{m}?

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FormalConjectures/ErdosProblems/

1119.lean

Retained formal statement5 of 5

Erdős [Er64g] also showed that the previous statement fails under the continuum hypothesis: if c=1\mathfrak{c} = \aleph_1, then there is an uncountable family of entire functions taking only countably many distinct values at each point z0Cz_0 \in \mathbb{C}.

FormalConjectures/ErdosProblems/1119.leanErdos1119.erdos_1119.variants.erdos_wetzel_ch2 linesExact file
Cardinal.continuum = Cardinal.aleph 1 →F, (∀ fF, Differentiablef) ∧ (∀ (z₀ : ℂ), {y | ∃ fF, f z₀ = y}.Countable) ∧ ¬F.Countable
SolvedStatement only, no proof

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