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Let's say I have defined $X$ = users type x and $Y$ = users type y, and I would like to define $u$ is element-of $X$ and also element of $Y$, is there a simpler way to express, or the expression below is in the simplest form?

$u =\{ e | e \in X \wedge e \in Y \} $

Thank you.

Regards, Andy.

1 Answers 1

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You can say that $u = X \cap Y$. This should be the easiest standard way to use set notation to denote this.

Hope that helps,

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    When dealing with sets, it is customary to use capital letters for sets and lowercase letters for elements. So, if you want to denote the set of all elements that are members of both $X$ and $Y$, then $U = X \cap Y$ is more typical. If you mean to simply denote a single element that happens to belong to both $X$ and $Y$, then you would say $u \in X \cap Y$ (the $\in$ means "element of").2011-12-05