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The main result from this note provides a constructive characterization of the valuative dimension, which bears a strong analogy to Lombardi's [7] constructive characterization of the Krull dimension. While Lombardi's characterization uses the lexicographic monomial order, ours uses the graded (reverse) lexicographic order or, in fact, any graded rational monomial order. Apart from this, the paper contains some related results and some examples which readers may find illuminating. [ABSTRACT FROM AUTHOR]

Abstract: We introduce the notion of independent sequences with respect to a monomial order by using the least terms of polynomials vanishing at the sequence. Our main result shows that the Krull dimension of a Noetherian ring is equal to the supremum of the length of independent sequences. The proof has led to other notions of independent sequences, which have interesting applications. For example, we can show that is the maximum number of analytically independent elements in an arbitrary ideal J of a local ring R and that if are (not necessarily finitely generated) subalgebras of a finitely generated algebra over a Noetherian Jacobson ring. [Copyright &y& Elsevier]

Abstract: Given a linear action of a group G on a K-vector space V, we consider the invariant ring , where is the dual space. We are particularly interested in the case where and G is the group of all upper unipotent matrices or the group of all upper triangular matrices in . In fact, we determine for and . The result is a complete intersection for all values of n and q. We present explicit lists of generating invariants and their relations. This makes an addition to the rather short list of “doubly parametrized” series of group actions whose invariant rings are known to have a uniform description. [Copyright &y& Elsevier]

Abstract: Let G be a finite group acting on a polynomial ring A over the field K and let denote the corresponding ring of invariants. Let B be the subalgebra of generated by all homogeneous elements of degree less than or equal to the group order . Then in general B is not equal to if the characteristic of K divides . However we prove that the field of fractions coincides with the field of invariants . We also study various localizations and homomorphisms of modular invariant rings as tools to construct generators for . We prove that there is always a nonzero transfer of degree , such that the localization can be generated by fractions of homogeneous invariants of degrees less than . If with finite-dimensional -module V, then c can be chosen in degree one and can be replaced by . Let denote the image of the classical Noether-homomorphism (see the definition in the paper). We prove that contains the transfer ideal and thus can be used to calculate generators for by standard elimination techniques using Gröbner-bases. This provides a new construction algorithm for . [Copyright &y& Elsevier]

Let A=BG, where B is a Noetherian algebra over a field K of characteristic p≠0 and G is a finite group such that p divides &z.sfnc;G&z.sfnc;. We give estimates for the depth of A in terms of the codimension of the branch locus of the extension B/A. [Copyright &y& Elsevier]