Abstract

The concept of -semihyperrings was introduced by Dehkordi and Davvaz as a generalization of semirings, semihyperrings, and -semiring. In this paper, by using the notion of triangular norms, we define the concept of triangular fuzzy sub- -semihyperrings as well as triangular fuzzy -hyperideals of a -semihyperring, and we study a few results in this respect.

1. Introduction

In [1], Nobusawa introduced -rings as a generalization of ternary rings. Let be an additive group whose elements are denoted by and another additive group whose elements are . Suppose that is defined to be an element of and that is defined to be an element of for every , and . If the products satisfy the following three conditions: , , ; ; (3) if for any and in , then ; then is called a -ring in the sense of Nobusawa [1]. Barnes [2] weakened slightly the conditions in the definition of -ring and gave a new definition of a -ring. Let and be two additive abelian groups. Suppose that there is a mapping from (sending into such that    , , ;    ; then is called a -ring in the sense of Barnes [2]. Nowadays, -rings mean the -rings due to Barnes and other -rings are known as -rings, that is, gamma rings in the sense of Nobusawa. Barnes [2], Luh [3], and Kyuno [4] studied the structure of -rings and obtained various generalization analogous to corresponding parts in ring theory. The notion of -semirings was introduced by Rao [5] as a generalization of semirings as well as -rings. Subsequently, by introducing the notion of operator semirings of a -semiring, Dutta and Sardar [6] enriched the theory of -semirings. Algebraic hyperstructures represent a natural extension of classical algebraic structures and they were introduced by the French mathematician Marty [7]. Algebraic hyperstructures are a suitable generalization of classical algebraic structures. In a classical algebraic structure, the composition of two elements is an element, while in an algebraic structure, the composition of two elements is a set. Since then, hundreds of papers and several books have been written on this topic, for example, see [810]. In [11, 12], Dehkordi and Davvaz studied the notion of a -semihyperring as a generalization of semiring, semihyperring, and -semiring.

Fuzzy sets are sets whose elements have degrees of membership. Fuzzy sets have been introduced by Zadeh (1965) as an extension of the classical notion of sets [13]. Let be a set. A fuzzy subset of is characterized by a membership function which associates with each point its grade or degree of membership . Fuzzy sets generalize classical sets since the characteristic functions of classical sets are special cases of the membership functions of fuzzy sets, if the latter only take values or . After the introduction of fuzzy sets by Zadeh, reconsideration of the concept of classical mathematics began. In 1971, Rosenfeld [14] introduced fuzzy sets in the context of group theory and formulated the concept of a fuzzy subgroup of a group. Das characterized fuzzy subgroups by their level of subgroups in [15], since then many notions of fuzzy group theory can be equivalently characterized with the help of notion of level subgroups. The concept of a fuzzy ideal of a ring was introduced by Liu [16]. In 1992, Jun and Lee [17] introduced the notion of fuzzy ideals in -rings and studied a few properties. In [6], Dutta and Sardar studied the structures of fuzzy ideals of -rings. Also, see [18]. The study of fuzzy hyperstructures is an interesting research topic of fuzzy sets. There is a considerable amount of work on the connections between fuzzy sets and hyperstructures. In [19], Davvaz introduced the concept of fuzzy -ideals of -rings. Then, this concept was studied in depth in several papers, for example, see [20]. Also, see [21]. In [22, 23], Ersoy and Davvaz investigated some properties of fuzzy -hyperideals of -semihyperring. Now, in this paper, we define the concept of triangular fuzzy sub- -semihyperrings and fuzzy -hyperideals of a -semihyperring by using triangular norms, and we study a few results in this respect.

2. Basic Concepts

Let be a nonempty set and let be the set of all nonempty subsets of . A hyperoperation on is a map and the couple is called a hypergroupoid. If and are nonempty subsets of , then we denote , and . A hypergroupoid is called a semihypergroup if for all of we have , which means that . A semihyperring is an algebraic structure which satisfies the following properties:    is a commutative semihypergroup; that is, and for all ;    is a semihypergroup; the hyperoperation is distributive with respect to the hyperoperation +; that is, for all ; the element is an absorbing element; that is for all . A semihyperring is called commutative if and only if for all . Vougiouklis in [24] studied the notion of semihyperrings in a general form; that is, both the sum and product are hyperoperations; also see [25]. A semihyperring with identity means that for all . The concept of -semihyperring is introduced and studied by Dehkordi and Davvaz [11]. Let be a commutative semihypergroup and be a commutative group. Then, is called a -semihyperring if there exists a map (image to be denoted by for and ) and is the set of all nonempty subsets of satisfying the following conditions:(1) , (2) , (3) , (4) , for all and for all . One can find many examples of -semihyperrings in [11, 12]. In the above definition if is a semigroup, then is called a multiplicative -semihyperring. A -semihyperring is called commutative if for every and . We say that -semihyperring with zero if there exists such that , for all and . Let and be two nonempty subsets of -semihyperring and . We define and . A nonempty subset of -semihyperring is called a sub- -semihyperring if it is closed with respect to the multiplication and addition. In other words, a nonempty subset of -semihyperring is a sub- -semihypergroup if and .

A right (left) -hyperideal of a -semihyperring is an additive sub-semihypergroup such that ( ). If is both right and left -hyperideal of , then we say that is a two-sided -hyperideal or simply a -hyperideal of . In [22, 23], Ersoy and Davvaz studied fuzzy -hyperideals of -semihyperrings. We recall the notion of a fuzzy -hyperideal of a -semihyperring. Let be a -semihyperring and be a fuzzy subset of . Then    is called a fuzzy left -hyperideal of if and for all and ;    is called a fuzzy right -hyperideal of if and for all and ; (3)   is called a fuzzy -hyperideal of if it is both a fuzzy left -hyperideal and a fuzzy right -hyperideal of .

The concept of a triangular norm was introduced by Menger [26] in order to generalize the triangular inequality of a metric. The current notion of a t-norm and its dual operation is due to Schweizer and Sklar [27]. By a t-norm we mean a function satisfying the following conditions: (T1) ; (T2) ; (T3) if ; (T4) , for all . For every t-norm , we set . A t-norm on is called a continuous t-norm if is a continuous function from to with respect to the usual topology. Note that the function “Min” is a continuous t-norm. A triangular conorm (t-norm for short) is a binary operation on the unit interval , that is, a function , which for all satisfies (T1)–(T3) and (S4) . From an axiomatic point of view, t-norms and t-conorms differ only with respect to their respective boundary conditions. In fact, the concepts of t-norms and t-conorms are dual in some sense. Anthony and Sherwood [28] redefined a fuzzy subgroup of a group by using the notion of t-norm.

3. -Fuzzy Sub- -Semihyperrings and -Fuzzy -Hyperideals

In this section, we define the notion of -fuzzy sub- -semihyperrings and -fuzzy -hyperideals of a -semihyperring and we study some of their properties. Let be a t-norm and be a fuzzy subset of a -semihyperring . Then, we say has imaginable property if .

Definition 1. Let be a -semihyperring, be a -norm, and be a fuzzy subset of . Then, is called a -fuzzy sub- -semihyperring of if(1) ,(2) , for all and for all .

A -fuzzy sub- -semihyperring of is said to be imaginable if it satisfies the imaginable property. Clearly, if is a -semiring, then is a -fuzzy sub- -semiring of when (1′) , (2′) ,for all and for all .

Example 2. Suppose that , the set of natural numbers, and is a nonempty subset of . For any and , we define and . Then, is a -semihyperring. We define the fuzzy subset of by and we consider the -norm , where . Then, for any and , we have On the other hand, we have the following cases:(1) , (2) and ,(3) . Regarding the above cases, we have , , and . Thus, in every case, we obtain Therefore, is a -fuzzy sub- -semihyperring of .

Lemma 3. Let be a -semihyperring, be a -norm, and be a -fuzzy sub- -semihyperring of . Then for all and , where

Proof. The proof is straightforward by mathematical induction.

Lemma 4. Let be a -semihyperring, be a -norm, and be a -fuzzy sub- -semihyperring of . Let and be nonempty subsets of . Then for all .

Proof. The proof is straightforward.

Theorem 5. Let be a -semihyperring, be a -norm, and be a fuzzy subset of with imaginable property and the maximum of . Then, the following two statements are equivalent:(1) is a -fuzzy sub- -semihyperring of ,(2) is a sub- -semihyperring of whenever and .

Proof. : Suppose that and . If , then , which implies that . Similarly, assume that and . If and , then . Then, we have , and so is a sub- -semihyperring of .
: Suppose that and . Since , both and are in . Now, we have and so . Assume that . If , then Now, let . Hence , which implies that and . Therefore and .

Definition 6. Let be a -semihyperring, be a -norm, and be a fuzzy subset of . Then(1) is called a -fuzzy left -hyperideal of if (2) is called a -fuzzy right -hyperideal of if (3) is called a -fuzzy -hyperideal of if it is both a -fuzzy left -hyperideal and a -fuzzy right -hyperideal of .

Theorem 7. Let be a -semihyperring, be a -norm, and be a fuzzy subset of with imaginable property and the maximum of . Then, the following two statements are equivalent:(1) is a -fuzzy -hyperideal of ,(2) is a -hyperideal of whenever and .

Proof. The proof is similar to the proof of Theorem 5.

Let be a fuzzy subset of and . The set is called a level subset of . So, we obtain the following corollary.

Corollary 8. Let be a -semihyperring and be a fuzzy subset of . Then(1) is a Min-fuzzy sub- -semihyperring of if and only if every nonempty level subset is a sub- -semihyperring of ;(2) is a Min-fuzzy -hyperideal of if and only if every nonempty level subset is a -hyperideal of .

Corollary 9. Let be a subset of . Then(1)the characteristic function is a -fuzzy sub- -semihyperring of if and only if is a sub- -semihyperring of ;(2)the characteristic function is a -fuzzy -hyperideal of if and only if is a -hyperideal of .

Theorem 10. Let be a -semihyperring and be a sub- -semihyperring of . Let be the -norm defined by and be a fuzzy subset of defined by for all and , where such that . Then, is a -fuzzy sub- -semihyperring of . In particular, if and , then is imaginable.

Proof. The proof is similar to the proof of Theorem  2.6 in [29].

Definition 11. Let and be and -semihyperrings, respectively. If there exists a map and a bijection such that for all and , then we say is a homomorphism from to . Also, if is a bijection then is called an isomorphism and and are isomorphic.

Proposition 12. Let and be and -semihyperrings, respectively. Let be a homomorphism from to . If is a -fuzzy sub- -semihyperring of , then is a -fuzzy sub- -semihyperring of too.

Proof. Suppose that and . Then, we have Therefore, is a -fuzzy sub- -semihyperring of .

Proposition 13. Let and be and -semihyperrings, respectively. Let be a homomorphism from to . If is a -fuzzy -hyperideal of , then is a -fuzzy -hyperideal of too.

Proof. The proof is similar to the proof of Proposition 12.

Let and be two sets of real numbers in . Then, we say is infinitely distributive if If is continuous, then is infinitely distributive [30].

Lemma 14. Let be a continuous -norm and be a family of -fuzzy sub- -semihyperring of . Then, is a -fuzzy sub- -semihyperring of .

Proof. For any and , we have

Lemma 15. Let and be and -semihyperrings, respectively, and be an onto homomorphism from to . Then, for every , we have .

Proof. The proof is similar to the proof of Lemma  3.5 in [31].

Proposition 16. Let and be and -semihyperrings, respectively, and let be a fuzzy subset of . Let be an onto homomorphism from to . If is a Min-fuzzy sub- -semihyperring of , then is a Min-fuzzy sub- -semihyperring of too.

Proof. Suppose that is a Max-fuzzy sub- -semihyperring of . By Corollary 8, is a Max-fuzzy sub- -semihyperring of if every nonempty level subset is a sub- -semihyperring of . Thus, assume that is any nonempty level subset. If , then , and if , then by Lemma 15, we have . By Corollary 8, for each is a sub- -semihyperring of . Hence, is a sub- -semihyperring of . By Lemma 14, being an intersection of a family of sub- -semihyperrings is also a sub- -semihyperring of and the proof is completed.

Definition 17. Let and be two -semihyperrings and let and be fuzzy subsets of and , respectively. The product of and is defined to be the fuzzy subset of with , for all .

Proposition 18. Let and be two -semihyperrings and let and be fuzzy subsets of and , respectively. Then(1)if and are -fuzzy sub- -semihyperrings of and , respectively, then is a -fuzzy sub- -semihyperring of ; (2)if and are -fuzzy -hyperideals of and , respectively, then is a -fuzzy -hyperideal of .

Proof. It is straightforward.

In [12], Dehkordi and Davvaz studied Noetherian and Artinian -semihyperrings in crisp case. A collection of subsets of a -semihyperring satisfies the ascending chain condition (or Acc) if there does not exist a properly ascending infinite chain of subsets from . Recall that a subset is a maximal element of if there does not exist a subset in that properly contains . Similar to [18], in the following, we obtain some results related to fuzzy sets and Noetherian -semihyperrings.

Proposition 19 (see [12]). Let be a -semihyperring. Then, the following conditions are equivalent:(1) satisfying the Acc condition on right (left) -hyperideals, (2)every nonempty family of right (left) -hyperideals has a maximal element, (3)every right (left) -hyperideals is finitely generated.

Definition 20 (see [12]). A -semihyperring is right (left) Noetherian if the equivalent conditions of the above proposition are satisfied. In the same way, we can define an Artinian -semihyperring. Let be a -hyperideal of a -semihyperring and be a Noetherian -semihyperring. Then, is called a Noetherian -hyperideal of .

Example 21 (see [12]). Let for every , , and . Then, is a Noetherian -semihyperring with respect to the following hyperoperations: where and .

Theorem 22. Let be a family of -hyperideals of a -semihyperring , where . Let be a fuzzy subset of defined by for all , where stands for . Let be a t-norm with . Then, is a -fuzzy -hyperideal of .

Proof. Let . Suppose that and for and . Without loss of generality we may assume that . Then, obviously . Since is a -hyperideal of , it follows that and which imply that and for all . If and , then . Hence, and . If and , then there exists such that . It follows that which implies that and for all . Finally, assume that and , then for some . Therefore, , and thus and , for all . Hence, is a -fuzzy -hyperideal of .

Theorem 23. Let be a -semiring satisfying descending chain condition, let be a fuzzy subset of , and let be a -norm with . Let be a -fuzzy -hyperideal of . If a sequence of elements of is strictly increasing, then has finite number of values.

Proof. Let be a strictly increasing sequence of elements of . Then . Then, is an ideal of for all Let . Then , and so . Hence . Since , there exists such that . It follows that but . Thus, and so we obtain a strictly descending sequence of -hyperideals of which is not terminating. This contradicts the assumption that satisfies the descending chain condition. Consequently, has finite number of values.

Theorem 24. Let be a -semiring, be a fuzzy subset of , and be a -norm with . Then, the following conditions are equivalent: (1) is a Noetherian -semihyperring,(2)the set of values of any -hyperideal of is a well-ordered subset of .

Proof. : Let be a -fuzzy -hyperideal of . Suppose that the set of values of is not a well-ordered subset of . Then, there exists a strictly decreasing sequence such that . It follows that is a strictly ascending chain of -hyperideals of , where , for every . This contradicts the assumption that is a Noetherian -semihyperring.
: Suppose that the condition is satisfied and is not a Noetherian -hyperring. There exists a strictly ascending chain of -hyperideals of . Note that is a -hyperideal of . Define a fuzzy subset in by We claim that is a -fuzzy -hyperideal of . Let . If and , then and . It follows that and , for all . Suppose that and for all . Since is a -hyperideal of , it follows that . Hence, and so . Similarly, for the case and , we have and , for all . Thus, is a -fuzzy -hyperideal of . Since the chain is not terminating, has a strictly descending sequence of values. This contradicts the assumption that the value set of any ideal is well-ordered. Therefore, is a Noetherian -semihyperring.

For a family of fuzzy subsets in , we define the join and the meet as follows: for all , where is any index set.

Theorem 25. The family of -fuzzy -hyperideals in is a completely distributive lattice with respect to meet “ ” and join “ ”.

Proof. Since is a completely distributive lattice with respect to the usual ordering in , it is sufficient to show that and are -fuzzy -hyperideals of for family of -fuzzy -hyperideals of . For any , we have
Now, let and . Then Hence, and are -fuzzy -hyperideals of . This completes the proof.

Conflict of Interests

The authors declare that there is no conflict of interests regarding the publication of this paper.