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I've been reading the book "SQL and Relational Theory: How to Write Accurate SQL Code" by C. J. Date. I have no formal background in CS, much less relational theory. Combined with the fact English is not my first language, I'm having a little trouble to understand a statement. At one moment (page 17) the author states:

... the number of attributes in the heading is the degree (sometimes the arity) ...

Does this means that the concept "degree" is equals with the concept "arity" (ie. I can use those words interchangeably) or this means that sometimes those concepts are equals (but not always)?

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up vote 4 down vote accepted

Yes, "degree" is equal to "-arity"; second degree is binary, third degree is ternary, etc.

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Thank you, Kevin. – Vitor Py Jul 9 '11 at 22:10

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