Polynomes à valeurs entières sur un anneau non analytiquement irréductible.
All rings considered are commutative with unit. A ring R is SISI (in Vámos' terminology) if every subdirectly irreducible factor ring R/I is self-injective. SISI rings include Noetherian rings, Morita rings and almost maximal valuation rings ([V1]). In [F3] we raised the question of whether a polynomial ring R[x] over a SISI ring R is again SISI. In this paper we show this is not the case.
Let be a polynomial with integral coefficients. Shapiro showed that if the values of at infinitely many blocks of consecutive integers are of the form , where is a polynomial with integral coefficients, then for some polynomial . In this paper, we show that if the values of at finitely many blocks of consecutive integers, each greater than a provided bound, are of the form where is an integer greater than 1, then for some polynomial .
Let be a field and . Let be a monomial ideal of and be monomials in . We prove that if form a filter-regular sequence on , then is pretty clean if and only if is pretty clean. Also, we show that if form a filter-regular sequence on , then Stanley’s conjecture is true for if and only if it is true for . Finally, we prove that if is a minimal set of generators for which form either a -sequence, proper sequence or strong -sequence (with respect to the reverse lexicographic...