Characterizations of hemirings by their $h$-ideals

Abstract

In this paper we characterize hemirings in which all $h$-ideals or all fuzzy $h$-ideals are idempotent. It is proved, among other results, that every $h$-ideal of a hemiring $R$ is idempotent if and only if the lattice of fuzzy $h$-ideals of $R$ is distributive under the sum and $h$-intrinsic product of fuzzy $h$-ideals or, equivalently, if and only if each fuzzy $h$-ideal of $R$ is intersection of those prime fuzzy $h$-ideals of $R$ which contain it. We also define two types of prime fuzzy $h$-ideals of $R$ and prove that, a non-constant $h$-ideal of $R$ is prime in the second sense if and only if each of its proper level set is a prime $h$-ideal of $R$