GSoC 2019 - Week 2 - Polycyclic Group Presentation in SymPy

11 Jun 2019

Hello world, The second week of coding period has been ended and for the complete week we worked on the presentation of polycyclic groups. I’ve created a WIP PR for the basic structure of PcGroups here but it seems like there are a lot of things that needs to be changed or enhanced in this presentation.

Initially I thought of representing PcGroups with just the generators of the given permutation group and then from the last week we already have composition-series(here) so we can easily compute the generating sequence(pcgs) for the polycyclic group. But, finally we realised that the composition-series will be too big to do all the computations for the PcGroup. Also, in the presentation we can’t ignore the relators.

So, after all this we thought of computing the smaller version of subnormal series with cyclic factors and finally we realised that collection algorithm is something that we need. Can’t say more about this because I have to look into the rewriting code which looks like a tough task for me but let’s hope for the best.

For the next week I’m setting these milestones for me:

• Get ready with the presentation of PcGroups(still I’m not sure if collection algorithm is what we need!).
• Implement exponent-vector which may further help in HallSubgroup computation.
• Include more methods in the PcGroup class.

Will try my best to execute things in order mentioned above. With this, sign out for the next week.

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