Upper bounds are established on the shifts in a minimal resolution of a multigraded module. Similar bounds are given on the coefficients in the numerator of the BackelinLescot rational expression for multigraded Poincaré series. Let K be a field and S = K[x1, . . . , xn] the polynomial ring with its natural n-grading. When I is an ideal generated by monomials in the variables x1, . . . , xn, th...

Abstract Can one tell if an ideal is radical just by looking at the degrees of generators? In general, this hopeless. However, there are special collections in multigraded polynomial rings, with property that any generated elements those radical. We call such a collection support. paper, we give combinatorial characterization supports. Our terms properties cycles associated labelled graph. also...

We introduce the multigraded Hilbert scheme, which parametrizes all homogeneous ideals with fixed Hilbert function in a polynomial ring that is graded by any abelian group. Our construction is widely applicable, it provides explicit equations, and it allows us to prove a range of new results, including Bayer’s conjecture on equations defining Grothendieck’s classical Hilbert scheme and the cons...