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More options Jul 16 2008, 3:37 am
From: Simon King <k...@mathematik.uni-jena.de>
Date: Wed, 16 Jul 2008 00:37:14 -0700 (PDT)
Local: Wed, Jul 16 2008 3:37 am
Subject: Re: call for success stories
Dear Harald,

On Jul 15, 12:15 pm, "Harald Schilly" <harald.schi...@gmail.com>
wrote:

> I am searching for interesting content and this time I want to ask
> everyone who has used Sage for his or her research or in education in
> class to write a short success story. It should talk about how it was
> used and the general and personal experience. Just some sentences to
> give new users a first impression of Sage.

I hope the following description isn't too long...

Project:
Computation of cohomology rings of finite p-groups with coefficients
in GF(p)

How Sage and its components were used:
- I use Gap to compute certain elementary abelian subgroups.
- Due to Cython, i can use C-programs of David Green for computing
minimal resolutions.
- Cython is a very nice python-like programming language, in which i
created classes for cochains, chain maps, cohomology rings etc.
- In order to find a minimal generating set and a minimal set of
relations for a cohomology ring, i need Gröbner basis computations in
graded commutative rings (or simply "commutative", in characteristic
2); Singular does that job.

Success story:
- Computation time for the cohomology rings of all 267 groups of order
64: About 2h40min in total (on a single CPU).
- Work in progress: Computation of the cohomology rings of groups of
order 128. So far successful for 2221 groups (i.e., 107 are still
missing). Computation time so far: 15 days, parallely on 4 CPUs.

General and personal experience:
- After learning a few days, wrapping the C-programs was surprisingly
easy.
- Writing Cython-code is fun!
- Communication with Singular via an ascii interface was painful until
i found some tricks to reduce the traffic.
- The non-commutative part of Singular has serious bugs. Hence, unless
i find a work around, i can use my programs only in characteristic 2.
- When problems occured, the Sage community was very responsive (Thank
you!)

Cheers
Simon