English
If f and g are L1-simple functions and they agree almost everywhere after applying toSimpleFunc, then their integrals are equal: if toSimpleFunc f =ᵐ[μ] toSimpleFunc g, then ∫ f = ∫ g.
Русский
Если две простые функции L1 совпадают почти повсеместно после применения toSimpleFunc, то их интегралы совпадают: если toSimpleFunc f =ᵐ[μ] toSimpleFunc g, то ∫ f = ∫ g.
LaTeX
$$$\text{toSimpleFunc } f =_{\mu}\!\!\! toSimpleFunc g \Rightarrow \int f = \int g$$$
Lean4
nonrec theorem integral_congr {f g : α →₁ₛ[μ] E} (h : toSimpleFunc f =ᵐ[μ] toSimpleFunc g) : integral f = integral g :=
SimpleFunc.integral_congr (SimpleFunc.integrable f) h