Salut!
On Wed, Sep 02, 2009 at 02:40:38PM -0700, Paul-Olivier Dehaye wrote:
> for all that's worth, that won't do for what i am trying. the point is
> to have the generality of alphabets.
Ah, now this is interesting. What exactly do you mean by "generality"
of alphabets? What would be very helpful would be a fake Sage session
demonstrating the features you would need (without worrying about the
syntactical details which we can figure out later).
> There is some structure for my computation (matching degrees of the
> polynomials over the two alphabets, which I was hoping to exploit with
> the PowerSeriesRing idea). In any case, it's more symmetric and gives
> a better presentation, so I am happier with this.
>
> There are bugs however, as this will demonstrate:
>
> S = SymmetricFunctions(QQ)
> s = S.s()
> p = S.p()
> ss = tensor([s,s])
> pp = tensor([p,p])
>
> a = tensor((s[5],s[5]))
> pp(a)
>
> The answer given,
> p[[5]] # p[[5]]
> is not correct
Yup. When I said "in the longer run, there will be support for mixed
coercions", I also included those coercions :-)
But yes, this should at least complain that the conversion is not
(yet) possible instead of returning a mathematically wrong result!
Thanks for pointing out this example which finishes to convince me
that the current very tolerant conversions provided by
CombinatorialFreeModule are *harmful*. See upcoming e-mail.
Cheers,
Nicolas
--
Nicolas M. Thiéry "Isil" <nthi...@users.sf.net>
http://Nicolas.Thiery.name/
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