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Prove that the relation “friendship” is not an equivalence relation on the set of all people in Chennai

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प्रश्न

Prove that the relation “friendship” is not an equivalence relation on the set of all people in Chennai

लघु उत्तर
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उत्तर

(a) S = aRa

Reflexivity would require aFa for every person a ∈ P, i.e., “everyone is a friend of themselves.” In ordinary usage, a person is not considered a friend of themselves. Hence a`\cancelF`a for all a, so F is not reflexive.

(b) aRb ⇒ bRa so it is symmetric

(c) aRb, bRc does not

⇒ aRc so it is not transitive

⇒ It is not an equivalence relation

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पाठ 1: Sets, Relations and Functions - Exercise 1.2 [पृष्ठ १८]

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सामाचीर कलवी Mathematics - Volume 1 and 2 [English] Class 11 TN Board
पाठ 1 Sets, Relations and Functions
Exercise 1.2 | Q 6 | पृष्ठ १८

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