I would like to propose a simple but large improvement to the commutative_dga package. In short, one currently cannot use the package to create graded commutative algebras that include non-closed degree 0 terms. (For example, this exclude the package from being used for the algebra of differential forms on a manifold, because any non-constant function is non-closed.)
For my purposes, this can be fixed easily, changing 1 line of code. However, I am unclear if this breaks parts of the module that I don't use. As I understand it, the only reason that degree 0 doesn't work is in the constructor for a new CDGA. If you pass a degree 0 generator, then the call in the constructor to create a g_algebra (line 1010) uses a TermOrder weighted by degree. But the TermOrder package assumes a polynomial ring with generators of positive weight, and so throws an error when you pass weight = degree = 0 generators. This can be fixed by using weight = degree + 1, but I worry that this might break some non-obvious assumption elsewhere. (It will also maybe mean that your monomials are ordered slightly differently than expected.) I can submit a pull request, but I read in the developer guide that it is best to start a discussion here first. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/5483cae3-e96e-4a55-a8f9-24bc215585aen%40googlegroups.com.
