Theorem 1. 4. ifAOB=AOC. then B=c Distributive laws and De Morgan's laws: B∩(A1UA2U.UAn)=(B∩A1)U(B∩A2)U.U(B∩A B∪(A1nA2n.∩A)=(BUA1)∩GB∪A2)n…n(B∪An) ∩4=∪4 ∪4=∩4 i=1Theorem 1.4: if AB=AC, then B=C Distributive laws and De Morgan’s laws: B∩(A1∪A2∪…∪An)=(B∩A1)∪(B∩A2)∪…∪(B∩An) B∪(A1∩A2∩…∩An)=(B∪A1)∩(B∪A2)∩…∩(B∪An)     n i i n i i n i i n i Ai A A A =1 =1 =1 =1 = =