On the linearity defect of the residue field

Abstract

Given a commutative Noetherian local ring $R$, the linearity defect of a finitely generated $R$-module $M$, denoted $\ld_R(M)$, is an invariant that measures how far $M$ and its syzygies are from having a linear resolution. Motivated by a positive known answer in the graded case, we study the question of whether $\ld_R(k)<\infty$ implies $\ld_R(k)=0$. We give answers in special cases, and we discuss several interpretations and refinements of the question.