free_formula (Definedness t r) = case sort of
        Nothing -> Definedness t' r
        Just s -> mkPredication (freePredSymb s) [t', t']
     where t' = free_term t
           sort = getSort t
free_formula (Definedness t r) = case sort of
        Nothing -> Definedness t' r
        Just s -> mkPredication (freePredSymb s) [t', t']
     where t' = free_term t
           sort = getSort t
free_formula (Definedness t r) = case sort of
        Nothing -> Definedness t' r
        Just s -> mkPredication (freePredSymb s) [t', t']
     where t' = free_term t
           sort = getSort t