[Axiom-mail] Combinatorics in PanAxiom

[Alasdair McAndrew]

Over the last few days, when I should have been doing other things, I've
been programming up a few combinatorial algorithms, to supplement those
already in the system. I've programmed as a sort of proof-of-concept in
the interactive language.

The functions include generators for powersets, subsets, set partitions,
permutations and derangements (of sets and multisets), and the numbers
involved.

So attached are two files: combinatorics.input, which contains the
programs, and combinatorics.pdf, which describes the functions.

If anybody is interested in (a) testing them, (b) rewriting these in spad,
or (c) adding to them, let me know!

-Alasdair