Sure! Happy to explain it. Although I have to say I'm not sure what textbooks are saying these days. When I talk to programmers right out of college sometimes there's a bit of confusion as they talk about patterns I know, but using different names. I grew up programming on an 8088. :)
In a podcast called College Info Geek and recently in I did a talk at Northwestern (The Garage) and I called what I'm doing "Emergent" because there are many competing little pieces. Let's see if I can explain it quickly here, though please don't be too hard on me I'm trying my best to answer a lot of questions, but I'm really happy to go more into later after all this dies down :) Conceptually, you could think of it as first creating what I'll call "song-bot", which acts a kind of overlord, and has some instructions from me (like maybe there's some specific chords I want it to use, keys to avoid, tempo, brainwave protocols, genre, etc, etc). This song-bot guy then spawns a bunch of little other bots that compete with each other for the right to play/fade in/or generally be a part of the final result. These little guys have different characteristics, like a "drum-bot" might has different places it "wants" to be placed, and so generally competes with other drums, but not always. Sometimes I'll even have little "bots" for individual notes of a certain instrument. They obey certain rules of course, to form a background, drum line, or a simple melody, and then they pass that information along to subsequent incarnations (there's some learning involved in that process, though I hesitate to give it any textbook term - man, you have me terrified here of defining something wrong! :) ). Through that learning, the pattern the original little guys made has more weight and will tend to repeat. But again, not always.
After a while, a song... emerges. A kind of "emergent intelligence."
The resulting song can be quite complex and varied. Of course there's more to it, because songs have sections, but all in all the genres I'm using are very structured. Techno especially, is very easy for the AI. Sometimes I'm tasked with creating a theme in a particularly difficult genre, and that's when it gets really tricky/fun (such as some of the Indian ones, which were labors of love). In these cases, I may have to re-rerun many "generations" of the AI through the same song from beginning to end, with different parameters/instruments, but with the same patterns/learning, because what can happen in these cases is that it starts out simple, and increases in complexity as it goes, so the start can sometimes be a bit boring.
Also keep in mind this is just a conceptual explanation. The code is much less amusing. Thinking of naming processes "bots" though just for fun.
I hope I explained it OK. Listen, I'm not saying it's Watson or anything, it's really just a necessary step I had to take in order to make the computer do what I wanted it to do. I tried out some different ideas, and this one worked the best. I like the result at least :)