new ((F → B) → B) → (C → (F ∧ E → (((E → B) → C) → (D ∨ F → (B ∧ C → (B ∧ A → B))))))
intro
intro
intro
cases 2
intro
intro
intro
cases 7
intro
cases 10
cases 2
cases 7
cases 10
exact 8