English
If i ∈ S, then generateFrom (π i) ≤ generateFrom (piiUnionInter π S). This is another form of monotonicity in the generating process.
Русский
Если i ∈ S, то generateFrom(π i) ≤ generateFrom(piiUnionInter π S).
LaTeX
$$$\forall x, x \in S \Rightarrow \mathrm{generateFrom}(\pi x) \le \mathrm{generateFrom}(\piiUnionInter(\pi) S)$$$
Lean4
theorem le_generateFrom_piiUnionInter {π : ι → Set (Set α)} (S : Set ι) {x : ι} (hxS : x ∈ S) :
generateFrom (π x) ≤ generateFrom (piiUnionInter π S) :=
generateFrom_mono (subset_piiUnionInter hxS)