Hello,
On May 17, 11:16 am, Haz <christian.mu...@gmail.com> wrote:
> The general idea is to have the combinatoric objects inherit from the most
> natural SymPy objects possible (Expr if a number is expected in the end,
> etc). For Permutations, that is Basic. I've advised Saptarshi to have
> Permutation accept any iterable that contains Expr objects. Specific
> algorithms that operate on permutations will be implemented to work with
> arbitrary Expr objects as best possible.
>
> Any feedback / thoughts on this approach?
Are you suggesting that things such as Permutation([x,y,z]) work? If
so, I will think that will cause more problems than it is worth -- in
fact, it isn't really well-defined. A permutation is a boijection
from a set to itself. The one-line permutation notation requires a
total ordering for the set. For example, without a ordering on
{x,y,z}, there isn't any way to make sense of Permutation([z,y,x]) *
Permutation([y,z,x]). If you really want to have permuations on sets
other than {1,...,n}, then you'll either need to make explicit the
underlying set.
--Mike
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