> I imagine at a place like Google, your "corpus" is just about everything under the sun, as are your queries. > What happens then? You accept the fact that a

> I imagine at a place like Google, your "corpus" is just about everything under the sun, as are your queries. > What happens then? You accept the fact that a good search engine is inevitably going to be a multi-layered beast that requires constant effort to improve, with heuristics, machine learning, magic constants, special lists of words, and regular expressions. After that, it's just a matter of picking a commercially useful objective function ("instant search", "query autocomplete", "maximize user satisfaction") and pointing large teams of well-resourced PhDs at it. Probably a whole weekend at least.