Dang, this new computer sends e-mails before y'r finished writing them.
About rules and breaking them and avant-garde -- the musician's need to play outside is what's important. Express yourself, Von keeps saying. Steve Lacy, who started as a teen-aged swing-dixie musician, gives a great description of breaking through to outside musical expression in Improvisation by Derek Bailey. The most pertinent thing said on the subject may have been by Ornette: teaching Cherry and Haden to play with him in the 1950s was a case of teaching them to be more confident in themselves.
While I'm rather inclined to agree with Allen, etc. about organizing solos to develop or at least reflect themes, there are always brilliant disorderly people like Paul Rutherford (at least in Discreet Harm of the Bourgeoisie), Bailey, Bennink to prove us wrong. But maybe total disorder is another kind of thematic improvisation.
Jazz In Search Of Itself is a wonder. Great to learn from. In about every article Kart points out something fundamental to the subject that I never noticed before. That's a great unsentimental style of writing; as a neighbor says, reading him is like listening to the music again. But, I think, freshly. Much as I admire writers like Giddins and Francis Davis, they drop out about where Kart digs in.