"Allow none of foo, one of foo or any number of foo"

Definetely NSFW

As a web search query, [-4^(1/4)] is interpreted like [-4 “1 4”], as in “Find me pages which contain a 1 next to a 4, but which do not contain a 4.” Thisshould return zero results, because it is impossible to satisfy both requirements. However, we have uncovered a bug that causes some web pages to “match” these contradictory queries. Since these are the only results that “match” the query, they are the results that get shown.