English
From a TendstoInMeasure relation, define a strictly increasing subsequence sequence that witnesses almost-everywhere convergence of a subsequence.
Русский
Из отношения TendstoInMeasure задайте строго возрастающую подпоследовательность, которая демонстрирует почти везде сходимость подпоследовательности.
LaTeX
$$$\text{Let } hfg: TendstoInMeasure(\mu,f,atTop,g). \text{ Then } seqTendstoAeSeq(hfg):\mathbb{N}\to\mathbb{N} \text{ is strictly increasing and ... }$$$
Lean4
/-- Transformation of `seqTendstoAeSeqAux` to makes sure it is strictly monotone. -/
noncomputable def seqTendstoAeSeq (hfg : TendstoInMeasure μ f atTop g) : ℕ → ℕ
| 0 => seqTendstoAeSeqAux hfg 0
| n + 1 => max (seqTendstoAeSeqAux hfg (n + 1)) (seqTendstoAeSeq hfg n + 1)