[Axiom-mail] Power series with coeffs in positive characteristic

[Marcus Better]

Hi all,

I am trying to compute with Laurent series over some unspecified field 
of postitive characteristic, where the coefficients may be indeterminate 
variables. I declare my power series as follows:

  z: ULS(FRAC POLY PrimeField 2, z, 0) := z

I can now create expressions like

  1/a*z^(-1)  + 1 + z^2 + b*z^4

which works nicely. The problem is to use GenerateUnivariatePowerSeries 
to generate series of this type. It seems that there is no such thing as 
Expression(PrimeField 2) which this package would expect.

I have defined a function
  coeffs: Integer -> FRAC POLY PrimeField 2
which computes the coefficients. How can I put them together into a 
power (or Laurent) series? The command
  series(n +-> coeffs(n), z=0)
just gives the error message
"Cannot find a definition or applicable library operation named series 
with argument type(s)
  AnonymousFunction
  Equation UnivariateLaurentSeries(Fraction Polynomial PrimeField 2,z,0)
"

There is a similar error if I declare z simply as FRAC POLY PrimeField 2.

Also, if I don't declare z at all, the above command gives me a UTS(EXPR 
INT,z,0) with the correct coefficients but treated as EXPR INT, which is 
not what I want. Is there any way I can get around this?

Thanks,

Marcus

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Marcus Better
Department of Mathematics                      Tel. +46 8 164539
Stockholm University                           Fax +46 8 6126717
SE-106 91 Stockholm
Sweden                                     http://www.math.su.se
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