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Abstract: This paper presents a new algorithm for the absolute factorization of parametric multivariate polynomials over the field of rational numbers. This algorithm decomposes the parameters space into a finite number of constructible sets. The absolutely irreducible factors of the input parametric polynomial are given uniformly in each constructible set. The algorithm is based on a parametric version of Hensel''s lemma and an algorithm for quantifier elimination in the theory of algebraically closed field in order to reduce the problem of finding absolute irreducible factors to that of representing solutions of zero-dimensional parametric polynomial systems. The complexity of this algorithm is single exponential in the number n of the variables of the input polynomial, its degree d w.r.t. these variables and the number r of the parameters. [Copyright &y& Elsevier]

Abstract: Two kinds of decompositions of a -module are introduced in this article, a Loewy-decomposition and a primary decomposition. Algorithms are described which allow to construct decompositions for finite-dimensional -modules. Both decompositions rely on the concept of the -module of relative syzygies introduced in the paper. Furthermore an algorithm is described which tests whether two given -modules are isomorphic under the relevant type of transformations. [Copyright &y& Elsevier]