Re: [Maxima-discuss] Permutations & Permutation Group Theory

[Robert S. <qu...@sy...>]

RobertD:

GAP has lots of functionality. Some things it has that CL-PERMUTATION
doesn't have:

- State-of-the-art implementations of perm group algorithms (like Monte
Carlo Schreier-Sims, etc.)
- Lots of useful (perm) group computations: sylow subgroups, maximal
subgroups, normal subgroups,
- Good support for working with homomorphisms (I'm working on this),
actions, products, etc.
- Matrix groups, finitely presented groups, lots of other non-perm-group
stuff.
- Lots of non-abstract-algebra stuff, like different arithmetics
(cyclotomic, p-adic, ...)
- Much more

GAP is extremely comprehensive, but it has grown wildly. It has its own
Pascal-like programming language and everything. I wanted a library in Lisp
where I could just write Lisp, not pseudo-Pascal.

I'm not sure how literal you meant "merging with Maxima". As for structure,
I'd prefer to keep the library as a library. I'm sure that'd be no problem
with some integration route.

Docs: I wouldn't mind writing texinfo documentation probably, but it would
be nice if the docs could be stand-alone and maybe cleverly integrated into
the manual.

Test examples: some exist in the README, and there's a growing test suite (
https://bitbucket.org/tarballs_are_good/cl-permutation/src/master/tests/).
More work could be put into this.

Closures: Some functions produce closures, but I don't think it's necessary
to import all of CL-PERMUTATION, just a useful subset. I think the best
route would be to make a wrapper package CL-PERMUTATION.MAXIMA or something
that makes Maxima-friendly wrapped calls to CL-PERMUTATION, handling stuff
like output data types, etc.

Cheers,

Robert Smith



On Mon, May 9, 2016 at 11:31 AM, Robert Dodier <rob...@gm...>
wrote:

> On 2016-05-09, Robert Smith <qu...@sy...> wrote:
>
> > I think CL-PERMUTATION may be good for inclusion as a share package. If
> > someone decides to get started on such a thing, I would be happy to
> > contribute and help maintain the best I can.
>
> Robert, thanks a lot, it looks like solid work. Can you briefly mention
> what are the areas in which GAP is more extensive? and also the overlap
> with existing Maxima functions, if any?
>
> Merging this into Maxima wouldn't take too much work. Functions visible
> to the user need to have names that begin with dollar sign, and instead
> of hyphens, names need to have underscores. I gather that some
> CL-PERMUTATION functions return closures, right? I don't know if Maxima
> handles these correctly, but if not, I think that could be relatively
> easy to fix (in Maxima).
>
> Looks like there is already some documentation, that's great. Maxima
> documentation is composed in Texinfo format, which is clunky and
> idiosyncratic but not any difficulty. Also it would be great to have a
> list of pairs of input/output expressions which can be used as a test
> script.
>
> best
>
> Robert Dodier
>
>
>
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