English
In a pseudo-metric space with an isometric SMul action, the left action preserves edistance: edist(c•x, c•y) = edist(x,y).
Русский
При изометрическом действии действует сохранение eddist слева: edist(c•x, c•y) = edist(x,y).
LaTeX
$$$\forall c\in M,\ \forall x,y:\; \mathrm{edist}(c\cdot x, c\cdot y) = \mathrm{edist}(x,y)$$$
Lean4
@[to_additive (attr := simp)]
theorem edist_smul_left [SMul M X] [IsIsometricSMul M X] (c : M) (x y : X) : edist (c • x) (c • y) = edist x y :=
isometry_smul X c x y