create_sigma_k :: Set.Set SORT -> CASLSign -> CASLSign
create_sigma_k ss sg_m = usg'
      where iota_sg = totalSignCopy sg_m
            usg = addSig const sg_m iota_sg
            om' = homomorphism_ops (sortSet sg_m) (opMap usg)
            om'' = make_ops ss om'
            usg' = usg { opMap = om'' }

{- | adds the make functions for the sorts in the initial module to the
operator map -}
create_sigma_k :: Set.Set SORT -> CASLSign -> CASLSign
create_sigma_k ss sg_m = usg'
      where iota_sg = totalSignCopy sg_m
            usg = addSig const sg_m iota_sg
            om' = homomorphism_ops (sortSet sg_m) (opMap usg)
            om'' = make_ops ss om'
            usg' = usg { opMap = om'' }

{- | adds the make functions for the sorts in the initial module to the
operator map -}
create_sigma_k ss sg_m = usg'
      where iota_sg = totalSignCopy sg_m
            usg = addSig const sg_m iota_sg
            om' = homomorphism_ops (sortSet sg_m) (opMap usg)
            om'' = make_ops ss om'
            usg' = usg { opMap = om'' }

{- | adds the make functions for the sorts in the initial module to the
operator map -}