r = [(1,4),(2,3),(3,2),(4,1)]
L = list_plot(r,rgbcolor=(1,0,0))
show(L)
r = [(1,-4),(2,-3),(3,-2),(4,-1)]
L = list_plot(r,rgbcolor=(1,0,0))
show(L)
G = SymmetricGroup(4)
g = G([(1,4),(2,3)])
[g(i) for i in [1,2,3,4]]