Emergence...not an LC subject?

Projects: 
While paging through Tripod last week in search of a book for the upcoming book review project, I noticed something very interesting: "emergence" is not considered a valid subject, at least in the eyes of the bibliographers who maintain the official Library of Congress subject headings. Even though the books on the suggested reading list all ostensibly represent perspectives on emergence, they are classified under a wide swath of subject headings ranging from "Graph Theory" and "Network Analysis" to "Complexity (Philosophy)" that never include any reference to "emergence." Even Wolfram's A New Kind of Science mentions nothing of emergence in its subject classifications: as far as the Library of Congress is concerned, it is merely a book about cellular automata and computational complexity. Though I know that LC headings frequently fail to capture the full thrust of a book's argument, I think that it's clear that Wolfram's work is about something more than just computation or CA. The closest the LC system comes to emergence is "self-organizing systems"--a good starting place, to be sure, but certainly not a full proxy for the concept of emergence as it has been introduced in class. Perhaps I'm just not familiar with the quirks and politics of the science area of the LC system, but it seems a bit strange that a concept that has raised such a fuss in the scientific community is conspicuously absent from the LC classification system. This, I think, points to a larger question raised at the beginning of the course, but never really settled (at least to my satisfaction): where does "emergence" fit into the taxonomy of science? Is it a wholly new branch off of the main "trunk" of science? Or is it merely an interdisciplinary subfield of math, computer science, physics, biology, etc.? I think this also raises some interesting questions as to how other sorts of interdisciplinary science fit into our conventional view of science as a neat taxonomy of discrete subjects. If one were to draw this classification system out, where would interdisciplinary fields such as emergence fit? How does this change our view of "science"?