Okay, well, I'm trying to understand minithesis.py, but I am despairing. The shrinking code (really everything in class TestingState) is too much to grok. You can tell from the amount of comments that this is the tour-de-force of the code, but the comments don't really help -- they seem to be mostly notes for people trying to reimplement this in another language. (Plus some snide remarks about QuickCheck.)

I suppose I have to read the paper at https://drmaciver.github.io/papers/reduction-via-generation-preview.pdf ... At least that has some drawings.

I am still unclear on some basics too, but presumably it's all related.

PS. What does "shortlex" mean?