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I saw a Tuple Relational Calculus formula, and it contained the symbol <>

I couldn't find any reference to it anywhere - can anyone tell me what this means? (perhaps this question will be a future first Google result)

Relational Calculus <>

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My relational calculus is extremely sketchy but isn't that just a "not equals"? –  Martin Smith Dec 29 '13 at 1:45

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As Martin said, this means "not equals"

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<> is not defined in relational calculus (or anywhere in math). It however is often used in programming languages (like SQL) to express "not equal". The correct sign would be the equal sign with a vertical line through its center. (= and | on top of each other).

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I haven't seen <> in a math textbook but if it was used, it would probably mean "less than or greater than" which is not exactly the same as != or (not equal). Unless the domain of possible values is totally ordered. –  ypercube Dec 29 '13 at 22:05

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