Let R₁ and R₂ be two equivalence relations on a set. Consider the following…
1998
Let R₁ and R₂ be two equivalence relations on a set. Consider the following assertions
(i) R₁ ∪ R₂ is an equivalence relation
(ii) R₁ ∩ R₂ is an equivalence relation
Which of the following is correct?
- A.
Both assertions are true
- B.
Assertions (i) is true but assertions (ii) is not true
- C.
Assertions (ii) is true but assertions (i) is not true
- D.
Neither (i) nor (ii) is true
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Correct answer: C
(i) R1∪R2 is not always an equivalence relation.
Although union may be reflexive and symmetric, it may fail to be transitive.
Hence, assertion (i) is false.
(ii) R1∩R2 is always an equivalence relation.
Intersection of two equivalence relations preserves:
Reflexivity
Symmetry
Transitivity
Hence, assertion (ii) is true.
Therefore, the correct option is:
(C) Assertions (ii) is true but assertions (i) is not true
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