let c1, c2, c3, c4, c5 be Complex; <*c1,c2,c3,c4,c5*> ^2 = <*(c1 ^2),(c2 ^2),(c3 ^2),(c4 ^2),(c5 ^2)*>
A1:
<*c1,c2,c3*> ^2 = <*(c1 ^2),(c2 ^2),(c3 ^2)*>
by Th9;
<*c4,c5*> ^2 = <*(c4 ^2),(c5 ^2)*>
by Th8;
hence
<*c1,c2,c3,c4,c5*> ^2 = <*(c1 ^2),(c2 ^2),(c3 ^2),(c4 ^2),(c5 ^2)*>
by A1, NUMBER15:59; verum