Set theory — true or false?

Exercise and reference answers

Questions

1. Statement is true

   Yes

   Statement

   |A ∪ B| = |A| + |B| − |A ∩ B|.

2. Statement is true

   Yes

   Statement

   The empty set is a subset of every set.

3. Statement is true

   No

   Statement

   (A ∪ B)' = A' ∪ B' (De Morgan).

4. Statement is true

   Yes

   Statement

   (A ∩ B)' = A' ∪ B' (De Morgan).