Announcement: new library decomp.lib

[gorzel]

For the next release I will provide

   
LIBRARY: decomp.lib  Functional Decomposition of Polynomials
AUTHOR:  Christian Gorzel, University of Muenster
email: gorzelc@math.uni-muenster.de


OVERVIEW: 
 Implements functional decomposition of multivariate polynomials. 

 D. Kozen, S. Landau: Polynomial Decomposition Algorithms,
                       J. Symb. Comp. (1989), 7, 445-456 
 J. von zu Gathen: Functional Decomposition of Polynomials: the Tame Case, 
                       J. Symb. Comp. (1990), 9, 281-299 

PROCEDURES:
 decompose(f[,1]);           [complete] functional decomposition of poly f
 is_composite(f);            predicate, is f a composite polynomial?
 chebyshev(n);               the nth Chebyshev polynomial of the first kind
 compose(I);                 compose entries of ideal


 Decomposes, if possible,  multivariate polynomials as
    f = h o g, where h is univariate and g is multivariate

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Applications:

• alg.number theory: intermediate fields k < k(f)

• simplified solving of univariate polynomial equations

• polynomial mapping: affine Stein factorization

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The implementation is much faster than

Maple's compoly or MUPAD's polylib::decompose

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[gorzel]

Could somebody have a look at it?

See also the examples at the end of the library, and compare with REDUCE's command decompose.

[hannes]

added decomp.lib as experimental