'Return True if ``self`` is injective.
That is, check if the elements of the domain are mapped to the same
codomain element.
>>> from sympy import QQ
>>> from sympy.abc import x
>>> from sympy.polys.agca import homomorphism
>>> F = QQ.old_poly_ring(x).free_module(2)
>>> h = homomorphism(F, F, [[1, 0], [x, 0]])
>>> h.is_injective()
False
>>> h.quotient_domain(h.kernel()).is_injective()
True'

def is_injective(self):

    return self.kernel().is_zero()
