[Graphics:submitted.nbgr344.gif] [Graphics:submitted.nbgr345.gif]

A proof by simplification works.

Simplification of the lhs term:

[Graphics:submitted.nbgr346.gif] = by [Graphics:submitted.nbgr347.gif]

[Graphics:submitted.nbgr348.gif] = by [Graphics:submitted.nbgr349.gif]

[Graphics:submitted.nbgr350.gif]

Simplification of the rhs term:

[Graphics:submitted.nbgr351.gif] = by [Graphics:submitted.nbgr352.gif]

[Graphics:submitted.nbgr353.gif]