同义词
1)contragredient representation,逆步表示2)contragredience,逆步3)contragredient,逆步4)ratational transforamation,逆步变换5)contragradience,逆步，反步6)contragradient Lie algebra,逆步李代数7)contragredient automorphism,逆步自同构8)reversible step motor,可逆步进电动机9)contragradient,逆步的，反步的，负梯度
