Thanks - this is very useful, and the whole question of the importance of writers in community is one that I'm glad to see getting more attention these days. I'm still not convinced that it's the best way to define a genre, however. As your example implies, some lines would exclude Conan Doyle, Poe and Collins as detective story writers - and when you get to that point it just seems perverse. (I think it may be Attebery who points out, in criticizing Rosemary Jackson's theories of fantasy, that a definition that excludes The Lord of the Rings as a fantasy - because it's not subversive enough - has more or less undermined itself from the start, and I'd have thought the same could be said here.)