English
Let τ1 ≤ τ2 be topologies on α and f: α → β. Then the coinduced topologies on β satisfy τ1.coinduced f ≤ τ2.coinduced f.
Русский
Пусть на α заданы топологии τ1, τ2 такие, что τ1 ≤ τ2, и отображение f: α → β. Тогда коиндуцированные топологии на β удовлетворяют τ1.coinduced f ≤ τ2.coinduced f.
LaTeX
$$$t_1 \le t_2 \implies t_1.coinduced f \le t_2.coinduced f$$$
Lean4
@[gcongr]
theorem coinduced_mono (h : t₁ ≤ t₂) : t₁.coinduced f ≤ t₂.coinduced f :=
(gc_coinduced_induced f).monotone_l h