The hash matches an infinite subset of infinite works. The same thing can glibly be said of any digital representation but the difference is that an algorithm exists to turn the number represented by the flac file back into sound that human beings can enjoy. None such exists for a hash it can never be turned back into the original nor even a piece of same.
Copyright isn't about mathematical derivatives its about protecting the licensed distributor as the sole source of the work. A single screen of a movie or a single page at least is part of the work. Even the first letter of the first word of a book represents a larger portion of the work. It's one nothingth of the work because you can't even derive that first letter from it. Judges are probably substantially interested in the purpose of the law. In math not so much.
Copyright isn't about mathematical derivatives its about protecting the licensed distributor as the sole source of the work. A single screen of a movie or a single page at least is part of the work. Even the first letter of the first word of a book represents a larger portion of the work. It's one nothingth of the work because you can't even derive that first letter from it. Judges are probably substantially interested in the purpose of the law. In math not so much.