∀ (𝕜 : Type u_2) {α : Type u_5} [inst : AddCommGroup 𝕜] [inst_1 : One 𝕜] [inst_2 : Preorder α]
  [inst_3 : LocallyFiniteOrder α] [inst_4 : DecidableEq α],
  IncidenceAlgebra.mu'✝ 𝕜 = { toFun := fun a b => IncidenceAlgebra.muFun'✝ 𝕜 b a, eq_zero_of_not_le' := ⋯ }