LetR be a complete local ring of dimension d over a perfect field of prime characteristic p, and let M be an R-module of finite length and finite projective dimension. S. Dutta showed that the equality limn→∞ `(F n R(M)) pnd = `(M) holds when the ring R is a complete intersection or a Gorenstein ring of dimension at most 3. We construct a module over a Gorenstein ring R of dimension five for wh...

In terms of the duality property of injective preenvelopes and flat precovers, we get an equivalent characterization of left Noetherian rings. For a left and right Noetherian ring R, we prove that the flat dimension of the injective envelope of any (Gorenstein) flat left R-module is at most the flat dimension of the injective envelope of RR. Then we get that the injective envelope of RR is (Gor...

In this paper, we discuss on the existence of filtrations of modules having good properties. In particular, we focus on filtered homomorphisms called strict, and show that there exists a filtration which makes a filtered homomorphism a strict filtered homomorphism. Moreover, by using this result, we study purity for filtered modules over a Gorenstein filtered ring.

Let Gn be the complete graph on the vertex set [n] = {1, 2, . . . , n} and ω an orientation of Gn , i.e., ω is an assignment of a direction i → j of each edge {i, j} of Gn . Let eq denote the qth unit coordinate vector of Rn . Write P(Gn ;ω) ⊂ R n for the convex hull of the (n 2 ) points ei − e j , where i → j is the direction of the edge {i, j} in the orientation ω. It will be proved that, for...

The classification of complete multipartite graphs whose edge rings are nearly Gorenstein as well that finite perfect stable set is achieved.