# Is anything wrong about this method of getting the elements of a set, that are in no other set? [closed]

Is anything wrong about this method of getting the elements of a set, that are in no other set?

I have sets A, B, C, D, E, and I'm trying to get the elements of set A that are not in any other set.

If Q is the union of B, C, D, and E.

And Z is the intersection of A, and Q.

What I want would be the symmetric difference between A, and Z?

## closed as unclear what you're asking by Henno Brandsma, max_zorn, José Carlos Santos, Namaste, ArsenBerkNov 2 '18 at 9:59

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• No, you'd want $A \backslash Q$. What's the purpose of $Z$? – Sambo Nov 1 '18 at 23:25
• @Sambo - Whoops, that was supposed to be "difference between A and Z", but I guess that's the wrong method anyway? ... Correcting question... – Malady Nov 2 '18 at 0:33

What you describe -- $$A\triangle (A\cap Q)$$ -- will give the right result, but is is simpler just to write $$A\setminus Q$$.
If you have a particular reason to prefer avoiding the $$\setminus$$ operation, it is fine to do what you do. Just make sure your reader(s) can see what this reason is, or the apparently convoluted procedure will probably confuse them a lot.