Subsets, 2.2

• Set A is a subset of the set B, (A ⊆B), if and only if every element of a is also an element of set B.
  • B = {1, 2, 3}.
  • List all of the subsets of set B.
  • If n(B) = x, there are 2^x subsets of B.
  • List several sets that are not subsets of B, why are they not subsets?
  • ∅ ⊆ B for all sets B.
  • Is ∅ ⊆ ∅? yes.
• The set A is a proper subset of the set B (A ⊂B) if A⊆ B and A≠B.
  • From the list above, which are not the proper subsets?
  • If n(B) = x, there are 2^x-1 proper subsets of B.
• Please do not confuse element ∈ with subset ⊂
  • ∈, ∉ indicates if something is in a set
    • They are relationships between elements and sets.
  • ⊂ ⊆ indicate if one set is contained in another
    • They are relationships between sets.
• Do some problems 5-26
• Do some problems 53-58