Normally torsion-freeness and normality criteria for monomial ideals

TL;DR

This paper investigates algebraic properties of monomial ideals, focusing on associated primes, normality, and torsion-freeness, introducing new concepts and providing counterexamples to existing conjectures.

Contribution

It introduces the concept of monomial ideals of well-nearly normally torsion-free type and explores their normality, along with counterexamples to several open questions.

Findings

Monomial ideals of well-nearly normally torsion-free type are normal.

Existence of embedded associated primes in powers of monomial ideals.

Counterexamples to conjectures relating algebraic properties of edge ideals.

Abstract

In this paper, we focus on the associated primes of powers of monomial ideals and asymptotic behavior properties such as normally torsion-freeness, normality, the strong persistence property, and the persistence property. In particular, we introduce the concept of monomial ideals of well-nearly normally torsion-free type, and show that these ideals are normal. After that, we present some results on the existence of embedded associated prime ideals in the associated primes set of powers of monomial ideals. Further, we employ them in investigating the edge and cover ideals of cones of graphs. Next, we present counterexamples to several questions concerning the relations between relevant algebraic properties of the edge ideals of clutters and complement clutters. We conclude by providing counterexamples to questions on the possible connections between normally torsion-freeness and normality of monomial ideals under polarization.