Example 4 Show that the relation R in the set {1, 2, 3} given by R = {(1, 1), (2, 2),(3, 3), (1, 2), (2, 3)} is reflexive but neither symmetric nor transitive. R = {(1, 1), (2, 2), (3, 3), (1, 2), (2, 3)} Check Reflexive If the relation is reflexive, then (a, a) ∈ R for every a ∈ {1, 2, 3} Since (1, 1) ∈ R ,(2, 2) ∈ R & (3, 3) ∈ R ∴ R is reflexive Check symmetric To check whether symmetric or not, If (a, b) ∈ R, then (b, a) ∈ R Here (1, 2) ∈ R , but (2, 1) ∉ R ∴ R is not symmetric Check transitive To check whether transitive or not, If (a,b) ∈ R & (b,c) ∈ R , then (a,c) ∈ R Here, (1, 2) ∈ R and (2, 3) ∈ R but (1, 3) ∉ R. ∴ R is not transitive Hence, R is reflexive but neither symmetric nor transitive.

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.

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