Recursive humor

A common joke (for example recursion in the Jargon File) is the following “definition” of recursion.

    Recursion

        See “Recursion”.

(Obviously, this recursion lacks the base case, so it will recur indefinitely.)

This is a parody on references in dictionaries, which in some cases may lead to circular definitions among related words. Jokes often have an element of wisdom, and also an element of misunderstanding. This one is also the shortest possible example of an erroneous recursive definition of an object, the error being the absence of the termination condition (or lack of the initial state, if looked at from an opposite point of view). Newcomers to recursion are often bewildered by its apparent circularity, until they learn to appreciate that a termination condition is key.

An example of this can be found by searching Google for the term “Recursion”. Google cleverly puts the searcher in an endless cycle, of suggesting “Recursion” as the word they were trying to spell, even though that's exactly the input they just used.

A variation is:

    Recursion

        If you still don't get it, see: “Recursion”.

which actually does terminate, as soon as the reader “gets it.”

— Wikipedia on Recursion

2010.03.15 Monday ACHK