An (A,B)-cyclic submodule M is generated by the states of one single trajectory of a linear control system whose parameters come from a commutative ring. M is “finite”, when it is generated by the states of a “deadbeat-control” process. Motivations and basic properties of such modules are given and among several further results it is shown that the family of finite (A,B)-cyclic submodules is an...

Throughout the paper, all rings are associative rings with identity 1. The set of all idempotents of a ring R is denoted by E(R). Also, for a subset X ⊆ R, we denote the right [resp., left] annihilator of X by r(X) [resp., (X)]. We call a ring R a left p.p.-ring [3], in brevity, an l.p.p.-ring, if every principal left ideal of R, regarded as a left R-module, is projective. Dually, we may define...

If I is a (two-sided) ideal of ring R, we let $${\text {ann}}_l(I)=\{r\in R\mid rI=0\},$$ {ann}}_r(I)=\{r\in Ir=0\},$$ and {ann}}(I)={\text {ann}}_l(I)\cap {\text {ann}}_r(I)$$ be the left, right double annihilators. An said to an annihilator if $$I={\text {ann}}(J)$$ for some J (equivalently, {ann}}({\text {ann}}(I))=I$$ ). We study ideals Leavitt path algebras graph $$C^*$$ -algebras. Let $$L...

We state several conditions under which comultiplication and weak comultiplication modulesare cyclic and study strong comultiplication modules and comultiplication rings. In particular,we will show that every faithful weak comultiplication module having a maximal submoduleover a reduced ring with a finite indecomposable decomposition is cyclic. Also we show that if M is an strong comultiplicati...

In this paper we study totally projective QTAG-modules and the extensions of bounded QTAG-modules. In the first section we study totally projective modules M/N and M ′/N ′ where N , N ′ are isomorphic nice submodules of M and M ′ respectively. In fact the height preserving isomorphism between nice submodules is extented to the isomorphism from M onto M ′ with the help of Ulm-Kaplansky invariant...

Invertibility of multiplication modules All rings are commutative with 1 and all modules are unital. Let R be a ring and M an R-module. M is called multiplication if for each submodule N of M, N=IM for some ideal I of R. Multiplication modules have recently received considerable attention during the last twenty years. In this talk we give the de nition of invertible submodules as a natural gene...

Let R = Z4 be the integer ring mod 4. A double cyclic code of length (r, s) over R is a set that can be partitioned into two parts that any cyclic shift of the coordinates of both parts leaves invariant the code. These codes can be viewed as R[x]-submodules of R[x]/(xr −1)×R[x]/(xs−1). In this paper, we determine the generator polynomials of this family of codes as R[x]-submodules of R[x]/(xr −...