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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?

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

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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

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