English
If the index set n is nonempty, the map I ↦ I.matrix n is strictly increasing: I ⊊ J implies I.matrix n ⊊ J.matrix n.
Русский
Если множество индексов ненулевое, отображение I ↦ I.matrix n strictly возрастает: I ⊊ J ⇒ I.matrix n ⊊ J.matrix n.
LaTeX
$$$$ [\\text{Nonempty } n] \\Rightarrow I \\subset J \\Rightarrow I^{\\mathrm{matrix}}_n \\subset J^{\\mathrm{matrix}}_n \\text{ with strict inclusion.} $$$$
Lean4
theorem matrix_strictMono_of_nonempty [h : Nonempty n] : StrictMono (matrix (R := R) n) :=
matrix_monotone n |>.strictMono_of_injective <|
.comp (fun _ _ => mk.inj) <| (RingCon.matrix_injective n).comp ringCon_injective