(Solved): Proposition 1.78. Given Ki K2 As Defined Above, Let ((x1, X2), (y1, Y2)) = (x1, 41 )x, + (x2, Y2 ), ...

Proposition 1.78. Given Ki K2 as defined above, let ((x1, x2), (y1, y2)) = (x1, 41 )x, + (x2, y2 ), . Then this map is an inner product on Ki o K2, and Ki o K2 is a Hilbert space under this inner product. Proof. Exercise 23.