Dear Jose et al.,
I think this could be a successful idea, assuming that the schedules of a good number of people line up in the right way to make it happen.
On organization:
I have heard about 'hackathons' employing the following mechanism to organize the work:
- People who have ideas for projects should pitch their project(s) to everybody else, in a presentation or document, before the work begins. This could be e.g. a prototype or sketch of the functionality that somebody wants to implement.
- After all these presentations, people can decide which project they want to contribute to, and each group can discuss the organization for their group, and the programming tasks they need to accomplish.
- If it seems like there are going to be a very large number of proposals, then some set of people probably need to be an organizing committee, to pre-screen the proposals and down-select for the most mature ones.
- I think this hackathon idea would be easiest using github (which is currently used for many xAct extensions), or somebody may want to host their own version control server using gitlab or other software. In general, I think having an official public git repo for xAct/xTensor could be quite beneficial -- github already has a mechanism for issue tracking and bug reporting, creating project boards (kanban style development), etc. I have seen Mma packages hosted on github with a mechanism to check whether or not there are updates from with Mma, by querying github (see e.g.
https://github.com/bshoshany/OGRe ).
On projects:
If I was to pitch a project, it would probably be to make an interface for users to create a Poisson algebra and do calculations with Poisson brackets. You can see an example with a nontrivial Poisson algebra in the ancillary notebook from this paper:
https://arxiv.org/abs/2012.06586 . Although in that example the Poisson algebra is on a phase space for finite number of degrees of freedom, I imagine that some folks might want to be able to do field space Poisson bracket calculations, like for the Hamiltonian formalism of GR or other field theories. Being able to automate constraint algebra calculations seems like a nice goal.
I could alternatively propose a project to xTerior for creating surfaces which can be paired with forms to represent integration; so that the variational derivative can actually act on an integral, and keep boundary terms. Doing this for arbitrary tensors instead of forms would be harder, so we should start with forms.
Best
Leo