1. ON THE SPECTRUM OF DERANGEMENT GRAPHS OF ORDER A PRODUCT OF THREE PRIMES

Modjtaba Ghorbani; Mina Rajabi-Parsa

Volume 6, Issue 2 , Winter and Spring 2019, Pages 81-89

Abstract
  A permutation with no fixed points is called a derangement. The subset $\mathcal{D}$ of a permutation group is derangement if all elements of $\mathcal{D}$ are derangement. Let $G$ be a permutation group, a derangementgraph is one with vertex set $G$ and derangement set $\mathcal{D}$ as connecting ...  Read More

2. On $\alpha $-semi-Short Modules

Maryam Davoudian

Volume 6, Issue 2 , Winter and Spring 2019, Pages 91-99

Abstract
  We introduce and study the concept of $\alpha $-semi short modules. Using this concept we extend some of the basic results of $\alpha $-short modules to $\alpha $-semi short modules. We observe that if $M$ is an $\alpha $-semi short module then the dual perfect dimension of $M$ is $\alpha $ ...  Read More

3. ON SEMI MAXIMAL FILTERS IN BL-ALGEBRAS

Akbar Paad; R. A. Borzooei

Volume 6, Issue 2 , Winter and Spring 2019, Pages 101-116

Abstract
  In this paper, first we study the semi maximal filters in linear $BL$-algebras and we prove that any semi maximal filter is a primary filter. Then, we investigate the radical of semi maximal filters in $BL$-algebras. Moreover, we determine the relationship between this filters and other types of filters ...  Read More

4. ON STRONGLY ASSOCIATIVE HYPERRINGS

Fatemeh Arabpur; Morteza Jafarpour

Volume 6, Issue 2 , Winter and Spring 2019, Pages 117-130

Abstract
  This paper generalizes the idea of strongly associative hyperoperation introduced in [7]  to the class of hyperrings. We introduce and investigate hyperrings of type 1, type 2 and SDIS. Moreover, we study some examples of these hyperrings and give a new kind of hyperrings called  totally hyperrings. ...  Read More

5. ON THE CAPACITY OF EILENBERG-MACLANE AND MOORE SPACES

Mojtaba Mohareri; Behrooz Mashayekhi; Hanieh Mirebrahimi

Volume 6, Issue 2 , Winter and Spring 2019, Pages 131-146

Abstract
  K. Borsuk in 1979, at the Topological Conference in Moscow, introduced concept of the capacity of a compactum and asked some questions concerning properties of the capacity ofcompacta. In this paper, we give partial positive answers to three of these questions in some cases. In fact, by describing spaces ...  Read More

6. ON EQUALITY OF ABSOLUTE CENTRAL AND CLASS PRESERVING AUTOMORPHISMS OF FINITE p-GROUPS

Rasoul Soleimani

Volume 6, Issue 2 , Winter and Spring 2019, Pages 147-155

Abstract
  Let $G$ be a finite non-abelian $p$-group and $L(G)$ denotes the absolute center of $G$. Also, let $\Aut^{L}(G)$ and $\Aut_c(G)$ denote the group of all absolute central and the class preserving automorphisms of $G$, respectively. In this paper, we give a necessary and sufficient condition for $G$ such ...  Read More

7. ON GRADED INJECTIVE DIMENSION

Akram Mahmoodi; Afsaneh Esmaeelnezhad

Volume 6, Issue 2 , Winter and Spring 2019, Pages 157-167

Abstract
  There are remarkable relations between the graded homological dimensions and the ordinary homological dimensions. In this paper, we study the injective dimension of a complex of graded modules and derive its some properties. In particular, we define the $^*$dualizing complex for a graded ring and investigate ...  Read More