Finite/infinite sets, equal sets, empty set ∅\varnothing∅, singleton, subset A⊆BA \subseteq BA⊆B, proper subset A⊊BA \subsetneq BA⊊B, power set P(A)P(A)P(A) with ∣P(A)∣=2∣A∣|P(A)| = 2^{|A|}∣P(A)∣=2∣A∣.