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## #1 2013-11-14 20:02:28

Debanjan
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### My question on set theory

let there be two sets A and B.

IF A=B then is A union B = A intersection B ??

I would love to know your logic behind the same.

Note : A and B can be any two types of sets.

## #2 2013-11-15 03:06:31

bobbym
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### Re: My question on set theory

Hi Debanjan;

If the two sets are equal then the union of them is the set itself and the intersection of them is the set itself so the answer is yes.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

rahat
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very difficult

## #4 2013-12-16 21:34:35

bobbym
Administrator

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### Re: My question on set theory

Hi rahat;

What do you not understand?

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

## #5 2013-12-16 22:45:10

bob bundy
Moderator

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### Re: My question on set theory

hi rahat,

Welcome to the forum.

A picture speaks a thousand words.  See below (click to make bigger).

The blue region is A intersect B.

The union is all in both circles.

Now what happens if you slide one circle so it coincides with the other?

Bob

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You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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