juooo1117

Sets 2 ∈ A : "2 is an element of A" 8 ∉ A : "8 is not an element of A" Cardinality: The cardinality(size) of a set is the number of elements in it. |A| = 4 : "there are 4 elements in A, so the cardinality is 4" Example using set theory X = set of people in a clinical trial, VBS: very bad syndrome 이라고 가정할 때, S = {𝒳 ∈ X : 𝒳 has VBS} H = {𝒳 ∈ X : 𝒳 does not have VBS} (단, X = S ∪ H, S ∩ H = ∅ 이라고 가정..