I see that; it just seems like they don't have a huge amount of practical utility. I mean, they're nice to have, but when I was programming in CL, one rarely if ever saw them in production code.
But I think you're right -- they have that "feeling the bits between your toes" character.
They're not necessary in order to have a list abstraction, but they are the minimal thing you could build lists out of.
The whole point of the axiomatic approach is that you don't program in the axioms themselves. But you still do want to have the things you do program in built out of the smallest set of axioms.
