English
If s is compact and f is monotone on s, then f lies in Lp(μ|_s) for any p, provided μ is finite on compact subsets (e.g., IsFiniteMeasureOnCompacts).
Русский
Если s компактно, а f монотонна на s, то f принадлежит Lp(μ|_s) для любого p, при условии, что μ ограничена на компактных подмножеств.
LaTeX
$$$f \in L^{p}(\mu\restriction s)$$$
Lean4
theorem memLp_isCompact [IsFiniteMeasureOnCompacts μ] (hs : IsCompact s) (hmono : MonotoneOn f s) :
MemLp f p (μ.restrict s) := by
obtain rfl | h := s.eq_empty_or_nonempty
· simp
· exact hmono.memLp_of_measure_ne_top (hs.isLeast_sInf h) (hs.isGreatest_sSup h) hs.measure_lt_top.ne hs.measurableSet