Zahra Parvizi - Department of Mathematics, Shahrekord Branch,Islamic Azad University, Shahrekord, Iran
Somayeh Motamed, - Department of Mathematics, Bandar Abbas Branch,Islamic Azad University, Bandar Abbas, Iran
Farhad Khaksar Haghani - Department of Mathematics, Shahrekord Branch,Islamic Azad University, Shahrekord, Iran,

In this paper, we define σ-normal filters, σ-fantastic filters, σ-obstinate filters, σ-integralfilters, σ-semi-integral filters in BL-algebras, then we state and prove some theorems to characterize theseconcepts. In this paper, we begin an algebraic investigation of new types of σ-filters in BL-algebras; whichcontains definitions, and their relationship. Finally, equivalent conditions are provided for easier study ofthese types of filters in BL-algebras and some important classes of BL-algebras and their connections arepresented.

σ-fantastic filter, σ-(semi) integral filter, σ -normal filter, σ-obstinate filter.