Need set notation help.

  • Thread starter ektrules
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  • #1
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Main Question or Discussion Point

Ok, I'm not very familiar with set notation. I was just wondering if the following is correct notation and means what I think:

{x[itex]\in[/itex]S : [itex]\exists[/itex]y[itex]\in[/itex]x, y[itex]\in[/itex]W}

S is a set of pairs of symbols (tuples of length 2 is the technical term I believe). W is a set of symbols.

What I want is the set of pairs in S that contain at least 1 symbol from set W.

Does my set builder notation correctly describe what I'm looking for? I don't necessarily have to use set builder notation; I just can't think of a way to describe it with unions, intersections, and quantifiers.
 

Answers and Replies

  • #2
CompuChip
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I think it is correct, however it may become slightly clearer if you explicitly write down the pairs:

[tex]\{ (x, y) \in S \mid x \in W \vee y \in W \}[/tex]

If you would like to omit the set builder notation, you could consider something like
[tex](W \times X) \cup (X \times W)[/tex]
where X is the set of all symbols (and [itex]W \subseteq X[/itex]).
 

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