. Which of the following collections form a partition of B*? For any that do, describe the blocks geometrically as subsets in the plane. For any that do not, explain why not. (a) For any > 0, define D; = {(z,y) B?*||z| + |y| =t} and let D = {D; |t = 0}. (b) For any r R, define B, = {(z,y) R?|2* +y =r} and let B = {B,.|r R}. (c) For and d > 0, define Cy = {(z,y) R?|z* + y* 0}. 2. Two partitions C and D of a set are given. Determine whether C is finer than D, coarser than D, or neither. (a) S=R2%C={{{z,y)|z > y}. {(z,y) |z y} {(z.y) |z =y} {(z.y) |z 4}, {z|z 4}} and D = {{z |z > 6}, {z| z