# Math Help - Abstract: Subgroups

1. ## Abstract: Subgroups

Show that a nonempty subset H of a group G is a subgroup of G if and only if a(b inverse) in H for all a,b, in H.

2. Originally Posted by fulltwist8
Show that a nonempty subset H of a group G is a subgroup of G if and only if a(b inverse) in H for all a,b, in H.
What properties does H need? Closure, associativity, identity, inverse. Can you show all of these?