English
If h ⊆ k are subsets of G, then closure(h) ≤ closure(k).
Русский
Если h ⊆ k — подмножества G, то closure(h) ≤ closure(k).
LaTeX
$$$ h \subseteq k \Rightarrow \mathrm{closure}(h) \le \mathrm{closure}(k) $$$
Lean4
/-- Subgroup closure of a set is monotone in its argument: if `h ⊆ k`,
then `closure h ≤ closure k`. -/
@[to_additive (attr := gcongr) /-- Additive subgroup closure of a set is monotone in its argument: if `h ⊆ k`,
then `closure h ≤ closure k` -/
]
theorem closure_mono ⦃h k : Set G⦄ (h' : h ⊆ k) : closure h ≤ closure k :=
(Subgroup.gi G).gc.monotone_l h'