G是一个群？ We must show that G is a group under composition of functions and find an isomorphism between G and G.We have closure under composition of functions since (Agoλh)(a)=入g(ha)=gha=入gh(a). Also, 入e(a)=ea=a and (入g-1o入g)(a）=入g-1(ga)=91ga=a=入e(a).𝐺ҧ是一个群？