arity

[bbeeton]

From a technical discussion in which I've been taking part: arity is the number of arguments or operands taken by a function or operator.

I don't think it has made its way into any "major" dictionary yet; I had to look it up so that I wouldn't have to ask, and thus appear too much of a Luddite to the other participants in the discussion.

[Slava]

Took me a few tries, but I think I get it now. Arity is the term to use to speak of the -aryness of something; binary, tertiary, etc.

The Greek equivalent is adicity, as in monad, dyad, etc.

[bbeeton]

My initial reaction was that it was a misspelling of "parity", but that seems not to be the case.

Perhaps a more comprehensible way to describe it is by example. In math, if a function q is dependent on x and y, the arity of q is 2.

(And to make the topic itself more evident, the original, and ongoing, discussion is about representation of math notation in publication and online communication.)

[Slava]

I thought of adding the p, too. Now that I've gotten around to looking it up, I realize I'd forgotten the second meaning of that combination of letters. There's the one we usually think of, that means equality or similarity, and then there's the one that means the state of having given birth. Different words that happen to use the same letters in the same order. Always fun.