def __init__(self, domain): Morphism.__init__( self, Hom(domain, domain.number_field, SetsWithPartialMaps()))
def __init__(self): Morphism.__init__(self, Hom(mpz, ZZ, ZZ.category(), check=False))
def __init__(self): Morphism.__init__(self, Hom(mpq, QQ, QQ.category(), check=False))
def __init__(self, domain): Morphism.__init__(self, Hom(domain, domain._isomorphic_vector_space, SetsWithPartialMaps()))