Heavy Metal and Natural Language Processing - Part 1

In this post I refer to lyrics of certain bands as being "Metal". I know some people have strong feelings about how genres are defined, and would probably disagree with me about some of the bands I call metal in this post. I call these band "Metal" here for the sake of brevity only, and I apologise in advance. It is all around us, and the rate at which it is produced in written, stored form is only increasing. It is also quite unlike any sort of data I have worked with before. Natural language is made up of sequences of discrete characters arranged into hierarchical groupings: words, sentences and documents, each with both syntactic structure and semantic meaning. Not only is the space of possible strings huge, but the interpretation of a small sections of a document can take on vastly different meanings depending on what context surround it.