2026/07/18 by Tony J. Puthenpurakal
#math.AC
Let (A,\mathfrakm) be a Noetherian local ring of dimension d and let M be a finitely generated A-module. Assume M has rank r > 0. We show that if M is NOT Cohen-Macaulay then μd(\mathfrakm, M) > r. If further A is unmixed and μn(\mathfrakm, M) ≤ 1 for some n ≥ d then we prove injdim M < ∞ and A is Cohen-Macaulay.