no goals
ι : Type ?u.71775
α : Type u_1
β : Type ?u.71781
π : ι → Type ?u.71786
inst✝ : GeneralizedBooleanAlgebra α
a b c d : α
⊢ a ∆ b ∆ c = a ∆ (b ∆ c)
rw [symmDiff_symmDiff_left, symmDiff_symmDiff_right]