Sets Union of sets:S UT,USi,UieI Si. Intersection of sets:SnT,nSi,Nier Si. Disjoint sets:empty pairwise intersection. Partition of set S:a collection of disjoint sets whose union is S. De Morgan's laws: U:Si=n;Si,∩S=USSets  Union of sets: 𝑆 ∪ 𝑇, 𝑆𝑖 ∞ 𝑖=1 , 𝑖∈𝐼 𝑆𝑖 .  Intersection of sets: 𝑆 ∩ 𝑇, 𝑆𝑖 ∞ 𝑖=1 , 𝑖∈𝐼 𝑆𝑖 .  Disjoint sets: empty pairwise intersection.  Partition of set 𝑆: a collection of disjoint sets whose union is 𝑆.  De Morgan’s laws: 𝑖 𝑆𝑖 = 𝑆𝑖 𝑖 , 𝑖 𝑆𝑖 = 𝑆𝑖 𝑖