I thought there was a horrible mismatch lurking in the definition of substitution extension, but upon closer inspection, it looks okay. I finished the hard case of soundness tonight. I'll try the other four or five tomorrow. They should be easy.
Up to 5292 words, 192 over my 1700/day goal, but tom7 and heather are still beating me. None of the three characters have met each other yet, and have engaged in a grand total of, like, two lines of dialogue, which occurred between character number three and some off-screen extras. Plenty of monologue, though, internal and external. Sooner or later I will have to make them collide. Maybe around the 10,000-word mark, I think. That gives me a few more days to set things up.
After KGB, cajoled rjmccall into doing some improv piano duet shit. Quite fun. There's something to be said for always straining to play rhythms as complicated as you can, or maybe even a bit beyond your abilities. I think it's much more fun and exciting to play in that way, as well as to play against someone with that style (which seemed to be yours, John, hope I'm not misrepresenting you) than a more conservative one.
During some other expermentation on the keyboard at home, discovered I really love the sound of a bVI-V transition in the ninth and tenth bars of the blues. Trying to work out some sort of sometimes-bIII-for-IV substitution to go along with it, but nothing good has come to me yet.