English
If Y equals Y' μ-a.e. and X equals X' μ-a.e., then condDistrib Y X μ = condDistrib Y' X' μ.
Русский
Если Y совпадает с Y' почти наверное и X совпадает с X' почти наверное, то condDistrib Y X μ = condDistrib Y' X' μ.
LaTeX
$$$$\\text{If } Y =_{μ}\\, Y' \\text{ and } X =_{μ}\\, X', \\quad \\mathrm{condDistrib}(Y,X,μ) = \\mathrm{condDistrib}(Y',X',μ). $$$$
Lean4
theorem condDistrib_congr {X' : α → β} {Y' : α → Ω} (hY : Y =ᵐ[μ] Y') (hX : X =ᵐ[μ] X') :
condDistrib Y X μ = condDistrib Y' X' μ :=
by
rw [condDistrib, condDistrib]
congr 1
rw [Measure.map_congr]
filter_upwards [hX, hY] with a ha hb using by rw [ha, hb]