> Now if I look under plethysmPowersum at
> http://www.sciface.com/support/doc/40/en/combinat/countingFunctions.html
> then it rather looks like the univariate case. "stretch" is multivariate
> (infinitely many variables).
That's indeed univariate; but we use the same name in our symmetric functions.
Now, if you go at another level of generality (plethysm of any
polynomial by any polynomial without reference to powersums), I am not
sure what's the right name is.
> BTW, I was a bit puzzled when I saw the formula for "plethysm".
>
> sum(g[k]*F(z^k), k)
> = sum(sum(g[d]*f[n/d], d)*z^n, n))
> = sum(f[k]*G(z^k), k)
>
> That somehow looks as if
>
> f pleth g = g pleth f
That's right, in the univariate case at least (I have to think twice
about the multivariate case).
> But then f(g) is usually not g(f) so how can this be connected with
> substitution?
Note that in Kerber's definition, plethysm is not just substitution;
there is some relabeling.
Cheers,
Nicolas
--
Nicolas M. Thiéry "Isil" <[EMAIL PROTECTED]>
http://Nicolas.Thiery.name/
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