English
If ν' s ≠ 0 and s has finite measure, then for a.e. x, the preimage ν' of s under the right-translation is finite and nonzero.
Русский
Если ν'(s) ≠ 0 и μ'(s) не бесконечна, то почти наверняка предобраз ν' по правому сдвигу имеет конечную, непустую меру.
LaTeX
$$$\forall^{\mathrm{ae}} x \partial \mu',\; \nu'( (\cdot * x)^{-1} s) < \infty$ и $\nu'( (\cdot * x)^{-1} s) \neq 0$ при условиях на ν' и s$$
Lean4
@[to_additive]
theorem ae_measure_preimage_mul_right_lt_top_of_ne_zero (h2s : ν' s ≠ 0) (h3s : ν' s ≠ ∞) :
∀ᵐ x ∂μ', ν' ((fun y => y * x) ⁻¹' s) < ∞ :=
by
refine (ae_measure_preimage_mul_right_lt_top ν' ν' h3s).filter_mono ?_
refine (absolutelyContinuous_of_isMulLeftInvariant μ' ν' ?_).ae_le
refine mt ?_ h2s
intro hν
rw [hν, Measure.coe_zero, Pi.zero_apply]