Nerval's Lobster writes "Facebook's Graph Search is an ambitious project: give users the ability to search through the social network's vast webs of data via natural-language queries. But that's much easier said—so to speak—than done. Although human beings think nothing of speaking in 'natural' language, a machine must not only learn all the grammatical building-blocks we take for granted—it needs to compensate for the quirks and errors that inevitably pop up in the course of speech. The Facebook team tasked with building Graph Search also knew that the alternate option, keyword-based search, wasn't a viable one. 'Keywords, which usually consist of nouns or proper nouns, can be nebulous in their intent,' Facebook engineering manager Xiao Li wrote in an April 29 posting on Facebook's blog. 'For example, "friends Facebook" can mean "friends on Facebook," "friends who work at Facebook Inc," or "friends who like Facebook the page."' That left the team with building a natural-language interface. The posting digs deep into the elements of the backend, including everything from 'parse trees' to a lexical analysis system."