Is A equal to B if A and B have the same union and intersection?

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SUMMARY

The discussion confirms that if the union of sets A and B equals A (A ∪ B = A) and the intersection of sets A and B equals A (A ∩ B = A), then it can be concluded that A is equal to B (A = B). This conclusion is supported by the logical deductions presented, where B is a subset of A and A is a subset of B, leading to the equality of the two sets. The affirmation of this conclusion was acknowledged by a participant named Micromass.

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zendani
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If A U B = A and A n B = A
can we say A = B ?

1: A U B = A => B C A => B n A = B
2: A n B = A => A C B => A U B = B

1,2 => A=B
 
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Yes, that is correct.
 
Thanks Micromass
 

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