Andrius is talking about »The Algebra of Copyright«. He is proposing a four-level model (PPT file) for determining the level of copyrights by the amount of parsing done with a work. I think you need to read his paper – I can’t summarize his thoughts here. It suppose it is a way to determine if you can use a work by looking at what you do with it.
David Weinberger has a good link for this material.