Lean4
/-- The infimum of a set of congruence relations on a given type with a multiplication. -/
@[to_additive /-- The infimum of a set of additive congruence relations on a given type with
an addition. -/
]
instance : InfSet (Con M) where
sInf
S :=
{ r := fun x y => ∀ c : Con M, c ∈ S → c x y
iseqv := ⟨fun x c _ => c.refl x, fun h c hc => c.symm <| h c hc, fun h1 h2 c hc => c.trans (h1 c hc) <| h2 c hc⟩
mul' := fun h1 h2 c hc => c.mul (h1 c hc) <| h2 c hc }