“…that over a Golod local ring that is not Gorenstein, every totally reflexive module is free. Another partial answer to Problem 1.30 is obtained by Yoshino [116], and by Christensen and Veliche [36]. The problem is also studied by Takahashi in [105].…”
Starting from the notion of totally reflexive modules, we survey the theory of Gorenstein homological dimensions for modules over commutative rings. The account includes the theory's connections with relative homological algebra and with studies of local ring homomorphisms. It ends close to the starting point: with a characterization of Gorenstein rings in terms of total acyclicity of complexes.
“…that over a Golod local ring that is not Gorenstein, every totally reflexive module is free. Another partial answer to Problem 1.30 is obtained by Yoshino [116], and by Christensen and Veliche [36]. The problem is also studied by Takahashi in [105].…”
Starting from the notion of totally reflexive modules, we survey the theory of Gorenstein homological dimensions for modules over commutative rings. The account includes the theory's connections with relative homological algebra and with studies of local ring homomorphisms. It ends close to the starting point: with a characterization of Gorenstein rings in terms of total acyclicity of complexes.
“…In light of Proposition 4.4, we write the coefficients of the polynomial d(t) in terms of the invariants a i , q ij , b and a for some special cases and provide a uniform expression of the Poincaré series in these cases. (1 + t) n−1 1 − t − (a 1 − 1)t 2 − (a 3 − q 11 )t 3 + q 12 t 4 − bt 5 .…”
Section: Applications To the Constructionmentioning
confidence: 99%
“…It follows that the kernel of the multiplication map φ 1 : A 1 ⊗ A 1 → A 2 is generated by a 2 1 − q 11 = 42 elements. We record the indices of basis elements of A 1 • A 1 by the set S = {(1, 2), (1,5), (1,6), (1, 7), (2, 3), (3,5), (4, 5)}.…”
In a paper in 1962, Golod proved that the Betti sequence of the residue field of a local ring attains an upper bound given by Serre if and only if the homology algebra of the Koszul complex of the ring has trivial multiplications and trivial Massey operations. This is the origin of the notion of Golod ring. Using the Koszul complex components he also constructed a minimal free resolution of the residue field. In this article, we extend this construction up to degree five for any local ring. We describe how the multiplicative structure and the triple Massey products of the homology of the Koszul algebra are involved in this construction. As a consequence, we provide explicit formulas for the first six terms of a sequence that measures how far the ring is from being Golod.
“…Define N = T/M and let F and G be free resolutions of M and N , respectively. Since R is local with 3 = 0 we can assume that F i = R n and G i = R for all i ≥ 0, [8]. By applying the Horseshoe Lemma, we get the…”
In this paper, we introduce a subcategory of totally reflexive modules that have a saturated filtration by other totally reflexive modules. We will prove these are precisely the totally reflexive modules with an upper triangular presentation matrix and that such a module has a complete resolution in which every differential can be simultaneously represented by upper triangular matrices.
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