Approximations in (bi-)hyperideals of Semihypergroups

Document Type : Regular Paper


1 School of Mathematics, Statistics and Computer Science, College of Sciences, University of Tehran, P.O. Box 14155-6455, Teheran, Iran

2 Department of Mathematics, University of Mazandaran, Babolsar, Iran

3 Department of Mathematics, Babol University of Technology, Babol, Iran


We consider the fundamental relation  on a semihypergroup  to interpret the lower and upper approximations as subsets of the fundamental semigroup  and we give some results in this connection. Also, we introduce the notion of a bi-hyperideal to study the relationship between approximations and bi-hyperideals.