In the present paper, we characterize all possible Hilbert functions of graded ideals in a polynomial ring whose regularity is smaller than or equal to d, where d is a positive integer. In addition, we prove the following result which is a generalization of Bigatti, Hulett and Pardue’s result: Let p ≥ 0 and d > 0 be integers. If the base field is a field of characteristic 0 and there is a grade...

1. Preliminaries 3 2. Gröbner Bases 3 2.1. Motivating Problems 3 2.2. Ordering of Monomials 3 2.3. The Division Algorithm in S = k[x1, . . . , xn] 5 2.4. Dickson’s Lemma 7 2.5. Gröbner Bases and the Hilbert Basis Theorem 10 2.6. Some Further Applications of Gröbner bases 18 3. Hilbert Functions 21 3.1. Macaulay’s Theorem 27 3.2. Hilbert Functions of Reduced Standard Graded k-algebras 37 3.3. Hi...

Let  $R$ be a commutative Noetherian ring and $I$ be an ideal of $R$. We say that $I$ satisfies the persistence property if  $mathrm{Ass}_R(R/I^k)subseteq mathrm{Ass}_R(R/I^{k+1})$ for all positive integers $kgeq 1$, which $mathrm{Ass}_R(R/I)$ denotes the set of associated prime ideals of $I$. In this paper, we introduce a class of square-free monomial ideals in the polynomial ring  $R=K[x_1,ld...

We show that the regularity of monomial ideals of K[x1, . . . , xn] (K being a field), whose associated prime ideals are totally ordered by inclusion is upper bounded by a linear function in n.

Let J ⊂ S = K[x0, . . . , xn] be a monomial strongly stable ideal. The collection Mf(J) of the homogeneous polynomial ideals I, such that the monomials outside J form a K-vector basis of S/I, is called a J-marked family. It can be endowed with a structure of affine scheme, called a J-marked scheme. For special ideals J , J-marked schemes provide an open cover of the Hilbert scheme Hilbnp(t), wh...

We investigate Gröbner bases of contraction ideals under monomial homomorphisms. As an application, we generalize the result of Aoki–Hibi–Ohsugi– Takemura and Ohsugi–Hibi for toric ideals of nested configurations.

We give a simple algorithm to decide whether a monomial ideal of nite colength in a polynomial ring is licci, i.e., in the linkage class of a complete intersection. The algorithm proves that whether or not such an ideal is licci does not depend on whether we restrict the linkage by only allowing monomial regular sequences, or homogeneous regular sequences, or arbitrary regular sequences. We app...

We study the structure of (minimal) free resolutions of monomial ideals over a polynomial ring. This has been a very active area of research, and a number of new ideas and approaches were introduced in the last decade. In this paper, we introduce three new notions: 1) We introduce the frame of a free resolution. The frame is a complex of vector spaces which encodes the structure of the resoluti...