Exercise
Suppose that H is a subgroup of G which is not
necessarily normal. Which of the following statement would fail to
hold concerning the map p : G ->
G/H, g -> gH
p
is surjective.
p is a morphism.
p has kernel H.
No.
In the image of gH we find g.
Correct. In fact, G/H need not be a group, so it does not make sense
to refer to the notion of group morphism.
No. The kernel of a map that is not a morphism has not been defined.
If we take the kernel of p to be p-1(e)
(as we did for moprhisms), then it is H.