A\B⊂A∪B′\mathrm {A \backslash B \subset A \cup B^{\prime}}A\B⊂A∪B′
A′\B′=B\A′\mathrm{A}^{\prime} \backslash \mathrm{B}^{\prime}=\mathrm{B} \backslash \mathrm{A}^{\prime}A′\B′=B\A′
A−B=A∩B′\mathrm {A-B=A \cap B^{\prime}}A−B=A∩B′
(A∣B)∩B=B\mathrm {(A \mid B) \cap B=B}(A∣B)∩B=B
