离散数学

Problem (1): Middle bit Problem (40 points) x1, x0, y1, y0 are bits. We will think of x1x0 and y1y0 as two 2-bit numbers. Let f (x1 , x0 , y1 , y0 ) = z2 z1 z0 , the binary representation of x1 x0 + y1 y0 . For example f (0, 1, 1,