Lean4
/-- The extended pseudometric induced by a function taking values in a pseudoemetric space.
See note [reducible non-instances]. -/
abbrev induced {α β} (f : α → β) (m : PseudoEMetricSpace β) : PseudoEMetricSpace α
where
edist x y := edist (f x) (f y)
edist_self _ := edist_self _
edist_comm _ _ := edist_comm _ _
edist_triangle _ _ _ := edist_triangle _ _ _
toUniformSpace := UniformSpace.comap f m.toUniformSpace
uniformity_edist := (uniformity_basis_edist.comap (Prod.map f f)).eq_biInf