KIET Group of Institutions, Ghaziabad
Department of Computer Applications
(An ISO – 9001: 2015 Certified & ‘A’ Grade accredited Institution by NAAC)
Operations on Sets
The basic set operations are:
1. Union of Sets: Union of Sets A and B is defined to be the set of all those elements which belong
to A or B or both and is denoted by A∪B.
1. A∪B = {x: x ∈ A or x ∈ B}
Example: Let A = {1, 2, 3}, B= {3, 4, 5, 6}
A∪B = {1, 2, 3, 4, 5, 6}.
2. Intersection of Sets: Intersection of two sets A and B is the set of all those elements which belong
to both A and B and is denoted by A ∩ B.
1. A ∩ B = {x: x ∈ A and x ∈ B}
Example: Let A = {11, 12, 13}, B = {13, 14, 15}
A ∩ B = {13}.
Page1|4
KIET Group of Institutions, Ghaziabad
Department of Computer Applications
(An ISO – 9001: 2015 Certified & ‘A’ Grade accredited Institution by NAAC)
3. Difference of Sets: The difference of two sets A and B is a set of all those elements which belongs
to A but do not belong to B and is denoted by A - B.
1. A - B = {x: x ∈ A and x ∉ B}
Example: Let A = {1, 2, 3, 4} and B = {3, 4, 5, 6} then A - B = {3, 4} and B - A = {5, 6}
4. Complement of a Set: The Complement of a Set A is a set of all those elements of the universal
set which do not belong to A and is denoted by Ac.
Ac = U - A = {x: x ∈ U and x ∉ A} = {x: x ∉ A}
Example: Let U is the set of all natural numbers.
A = {1, 2, 3}
Ac = {all natural numbers except 1, 2, and 3}.
Page2|4
KIET Group of Institutions, Ghaziabad
Department of Computer Applications
(An ISO – 9001: 2015 Certified & ‘A’ Grade accredited Institution by NAAC)
5. Symmetric Difference of Sets: The symmetric difference of two sets A and B is the set
containing all the elements that are in A or B but not in both and is denoted by A ⨁ B i.e.
1. A ⨁ B = (A ∪ B) - (A ∩ B)
Example: Let A = {a, b, c, d}
B = {a, b, l, m}
A ⨁ B = {c, d, l, m}
Algebra of Sets
Sets under the operations of union, intersection, and complement satisfy various laws (identities)
which are listed in below Table.
Table: Law of Algebra of Sets
Idempotent Laws (a) A ∪ A = A (b) A ∩ A = A
Associative Laws (a) (A ∪ B) ∪ C = A ∪ (B ∪ (b) (A ∩ B) ∩ C = A ∩ (B ∩
C) C)
Commutative (a) A ∪ B = B ∪ A (b) A ∩ B = B ∩ A
Laws
Distributive Laws (a) A ∪ (B ∩ C) = (A ∪ B) ∩ (b) A ∩ (B ∪ C) =(A ∩ B) ∪
(A ∪ C) (A ∩ C)
De Morgan's (a) (A ∪B)c=Ac∩ Bc (b) (A ∩B)c=Ac∪ Bc
Laws
Page3|4
KIET Group of Institutions, Ghaziabad
Department of Computer Applications
(An ISO – 9001: 2015 Certified & ‘A’ Grade accredited Institution by NAAC)
Identity Laws (a) A ∪ ∅ = A (c) A ∩ U =A
(b) A ∪ U = U (d) A ∩ ∅ = ∅
Complement (a) A ∪ Ac= U (c) Uc= ∅
Laws (b) A ∩ Ac= ∅ (d) ∅c = U
Involution Law (a) (Ac)c = A
Page4|4