Let A = f1; 2; 3; 4; a; b; cg, B = f1; 2; 5; 6; b; c; d; e; fg, C = f1; 2; a; d; g; hg.

(a) Is 1 2 A? Is f1g 2 A? Is f1; 2g µ A?

(b) Compute A \ B and A [ B.

(c) Compute (A \ B) [ C and A \ (B [ C). Are they equal?

(d) Show (A\B) [ C = (A[ C) \ (B [ C) and A\ (B [ C) = (A\B) [ (A\ C) for these particular choices of A, B and C.

(e) Define A¡B = A\B0. Compute A¡B and B¡A. Is A[B = (A¡B)[(B¡A)[(A\B)?

(f) What are #A, #B, #(A\B). How to use these three quantities to compute #(A[B)?