English
The trim-to-Lp map preserves addition: lpMeasSubgroupToLpTrim of f+g equals the sum of the trims.
Русский
Перенос через обрезку сохраняет сложение: lpMeasSubgroupToLpTrim(f+g) = lpMeasSubgroupToLpTrim(f) + lpMeasSubgroupToLpTrim(g).
LaTeX
$$$lpMeasSubgroupToLpTrim\ F\ p\ μ hm (f+g) = lpMeasSubgroupToLpTrim\ F\ p\ μ hm f + lpMeasSubgroupToLpTrim\ F\ p\ μ hm g$$$
Lean4
theorem lpMeasSubgroupToLpTrim_add (hm : m ≤ m0) (f g : lpMeasSubgroup F m p μ) :
lpMeasSubgroupToLpTrim F p μ hm (f + g) = lpMeasSubgroupToLpTrim F p μ hm f + lpMeasSubgroupToLpTrim F p μ hm g :=
by
ext1
grw [Lp.coeFn_add]
refine (Lp.stronglyMeasurable _).ae_eq_trim_of_stronglyMeasurable hm ?_ ?_
· exact (Lp.stronglyMeasurable _).add (Lp.stronglyMeasurable _)
grw [lpMeasSubgroupToLpTrim_ae_eq, lpMeasSubgroupToLpTrim_ae_eq, lpMeasSubgroupToLpTrim_ae_eq, ← Lp.coeFn_add]
rfl