Venn diagrams The diagram drawn to represent sets are called Venn-diagram. In Venn-diagram the universal set U is represented by points within the rectangle and its subsets are represented points in closed curves (usually circles) within the rectangle. If a set A is a subset of a set B, then the circles representing A is…

Union of sets Let A and B be two sets. The union of A and B is the set of all those elements which belong either to A or to B or to both A and B. We denote A union B by notation “A ∪ B” Thus  A∪B = { x : x ∈…

Intersection of sets Let A and B be two sets. The intersection of A and B is the set of all those elements that belongs to both A and B. See in Fig(v) shaded region show A∩B We denote A intersection B by notation “A ∩ B” Thus  A∩B = { x : x ∈…

Disjoint sets Two sets A and B are said to be disjoint, if A∩B=Φ. If A∩B≠Φ, then A and B are said to be intersecting or overlapping sets As shown in Fig(vi) Fig(vi)  Example If A={ 1, 2, 3, 4, 5, 6 }, B={ 7, 8, 9, 10, 11 } and C= { 6, 8, 10,…

Difference of sets Let A and B be two sets. The difference of A and B written as A – B, is the set of all those elements of A which do not belong to set B Thus A – B={ x : x ∈ A and x  ∉ B} or  A – B={ x…

Symmetry difference of sets Let A and B be two sets. The symmetry difference of sets A and B is the set (A-B) ∪ (B-A)  and it is denoted by A ∆ B. Then A∆B=(A-B) ∪ (B-A) = {x : x ∉ A ∩ B}. In Fig 9 shaded region represents A∆B Fig (9) Example…

Complement of a set Let U be the universal set and let A be a set such that A ⊂ U. Then the complement of A with respect to U is denoted by A’ or Ac or U-A and is defined the set of all those elements of U which are not in A. Thus…

Laws of algebra of set THEOREM 1 (Idempotent Laws) For any set A (i) A ∪ A = A (ii) A ∩ A = A PROOF  (i) A ∪ A= { x : x ∈ A or x ∈ A} ={x : x ∈ A} = A    (ii) A ∩ A = {x : x…

Relation Let A and B be two sets. Then a relation from set A to B is a subset of A × B. Thus, R is a relation from A to B⇔R ⊆ A × B. If R is a relation from a non-void set A to non-void set B and my if (a, b)…

Domain of relation Let R be a relation from a set A to a set B. Then the of all first components or coordinates of the ordered pairs belonging to R is called the domain of R. Thus, domain of R = { a : (a, b) ∈ R} Clearly, domain of R ⊆  A…