[GAP Forum] Multivariate Laurent-Polynomials

[Johannes Hahn]

Hi everyone.

I'm currently working on some stuff with Hecke-algebras and as there is
still no CHEVIE for GAP4, I implemented the features I need myself. It
works fine (more or less) for the equal-parameter case. It would work
equally fine for the multiparameter-case (almost) without changes if
there was a good way to deal with multivariate Laurent polynomials.

So what do want to do? I want to specify a monomial ordering (i.e. a
total ordering of Z^r which is invariant under addition) and be able to
do these three elementary things:
- extract to lowest exponent (w.r.t. the chosen ordering) and its
coefficient
- split a Laurent polynomial into the part consisting of all terms with
positive exponent, the part with negative exponents and the coefficient
for the exponent zero.
- apply the bar-automorphism, i.e. I want to be able to flip all signs
in the exponents.


Did I just overlook these features in the reference? If not: Are they
hidden somewhere in the system and just not documented or is there at
least a package that does these things?


Johannes Hahn
(University Jena, Germany)