D. Rees and J. Sally defined the core of an R-ideal I as the intersection of all (minimal) reductions of I. However, it is not easy to give an explicit characterization of it in terms of data attached to the ideal. Until recently, the only case in which a closed formula was known is the one of integrally closed ideals in a two-dimensional regular local ring, due to C. Huneke and I. Swanson. The...

Let R = k[x 1 , · · · , x n ] be a polynomial ring and let I ⊂ R be a graded ideal. In [16], Römer asked whether under the Cohen-Macaulay assumption the i-th Betti number β i (R/I) can be bounded above by a function of the maximal shifts in the minimal graded free R-resolution of R/I as well as bounded below by a function of the minimal shifts. The goal of this paper is to establish such bounds...

Let u1×n, Xn×n, and vn×1 be matrices of indeterminates, AdjX be the classical adjoint of X, and H(n) be the ideal I1(uX)+ I1(Xv)+ I1(vu−AdjX). Vasconcelos has conjectured that H(n) is a perfect Gorenstein ideal of grade 2n. In this paper, we obtain the minimal free resolution of H(n); and thereby establish Vasconcelos’ conjecture. Let u1×n, Xn×n, and vn×1 be matrices of indeterminates over a co...

This paper studies Ulrich ideals in hypersurface rings. A characterization of is given. Using this characterization, we construct a minimal free resolution an ideal concretely. We also explore ring the form R=k[[X,Y]]/(f).

in this paper, we introduce a new generalization of weakly prime ideals called $i$-prime. suppose $r$ is a commutative ring with identity and $i$ a fixed ideal of $r$. a proper ideal $p$ of $r$ is $i$-prime if for $a, b in r$ with $ab in p-ip$ implies either $a in p$ or $b in p$. we give some characterizations of $i$-prime ideals and study some of its properties.  moreover, we give conditions  ...

In this paper, the definition of Stone-Čech defined on discrete topological space natural numbers is used, which set all ultra-filters and largest compact created from space. The algebraic properties will be used to understand study some it. We have expanded semi-group process ( , naturally compactification . use illustrate structure, emphasizing smallest ideal where show that containing a mini...

For P a poset or lattice, let Id(P ) denote the poset, respectively, lattice, of upward directed downsets in P, including the empty set, and let id(P ) = Id(P )−{∅}. This note obtains various results to the effect that Id(P ) is always, and id(P ) often, “essentially larger” than P. In the first vein, we find that a poset P admits no <-respecting map (and so in particular, no one-to-one isotone...

This paper shows that any compactly generated lattice is a subdirect product of subdirectly irreducible lattices which are complete and upper continuous. An example of a compactly generated lattice which cannot be subdirectly decomposed into subdirectly irreducible compactly generated lattices is given. In the case of an ideal lattice of a lattice L, the decomposition into subdirectly irreducib...

The Koszul homology of modules of the polynomial ring R is a central object in commutative algebra. It is strongly related with the minimal free resolution of these modules, and thus with regularity, Hilbert functions, etc. Here we consider the case of modules of the form R/I where I is a monomial ideal. So far, some good algorithms have been given in the literature and implemented in different...