Ex 4.2 is unclear

[JanneM]

Exercise 4.2 (page 59) is unclear: Prove De Morgans law for sets (A∩B)^C ? A^C∪B^C. "C" is never defined, and as the preceding exercise is on power sets, this suggests that "x^C" should be read as a power set with the set C, not as the set complement.

[j2kun]

Definition 4.3 defines the notation, but I agree it's confusing juxtaposed with the previous exercise. If you submit an erratum at pimbook.org, I'll fix it and credit you :)

Thanks for the note!