symmetry_axs :: Set.Set SORT -> CASLFORMULA
symmetry_axs ss = conj
     where axs = Set.fold ((:) . symmetry_ax) [] ss
           conj = conjunct axs

-- | computes the symmetry axiom of a concrete sort for the kernel of h
symmetry_axs :: Set.Set SORT -> CASLFORMULA
symmetry_axs ss = conj
     where axs = Set.fold ((:) . symmetry_ax) [] ss
           conj = conjunct axs

-- | computes the symmetry axiom of a concrete sort for the kernel of h
symmetry_axs ss = conj
     where axs = Set.fold ((:) . symmetry_ax) [] ss
           conj = conjunct axs

-- | computes the symmetry axiom of a concrete sort for the kernel of h