let a, b be Element of D * ; :: thesis: H2(G1) . a,b = H2(G2) . a,b reconsider a2 = a, b2 = b as Element of G2 by A8; reconsider a1 = a, b1 = b as Element of G1 by A6; reconsider p = a, q = b as Element of D * ;
( a2 [*] b2 = p ^ q & a1 [*] b1 = p ^ q )
by A7, A9; hence
H2(G1) . a,b = H2(G2) . a,b
; :: thesis: verum