EUROPEAN JOURNAL OF PURE AND APPLIED MATHEMATICS Vol. 13, No. 2, 2020, 200-215 ISSN 1307-5543 – www.ejpam.com Published by New York Business Global Applications of Neutrosophic N -Structures in n-Ary Groupoids Amornrat Rattana1,∗, Ronnason Chinram1,2 1 Department of Mathematics and Statistics, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand 2 Centre of Excellence in Mathematics, CHE, Si Ayuthaya Road, Bangkok 10400, Thailand Abstract. This paper includes the notions of neutrosophic n-aryN -subgroupoids of n-ary groupoids and some properties. 2020 Mathematics Subject Classifications: 20N15, 03B80 Key Words and Phrases: neutrosophic N -structures, n-ary groupoids, neutrosophic n-ary N - subgroupoids, ε-neutrosophic n-ary N -subgroupoids. 1. Introduction In 1965, the degree of membership/truth (t) and the fuzzy set were introduced by Zadeh [12]. Atanassov [1] introduced the degree of nonmembership/falsehood (f) and defined the intuitionistic fuzzy set in 1986. Neutrosophy, means knowledge of neutral, is a branch of philosophy introduced as a theory of generalization of dialectic in 1995 by Smarandache. He proposed the term neutrosophic because neutrosophic originally comes from neutrosophy. In 1999, he introduced the concept of neutrosophic logics [9] and introduced the degree of indeterminancy/neuterality (i) and proposed the neutrosophic set on three components (t, i, f) =(truth, indeterminacy, falsehood). Jun et al. [11] introduced a negative-valued function and defined N -structures in 2009. Khan et al. [4] investigated the notion of neutrosophic N -structures and their applications in semigroups in 2017. Jun et al. [10, 11] considered neutrosophic N -structures applied to BCK/BCI-algebras. Song et al. [8] proposed neutrosophic commutative N -ideals in BCK-algebras in 2017. Rangsuk et al. [6] discussed neutrosophic N -structures and their applications in UP-algebras. ∗Corresponding author. DOI: https://doi.org/10.29020/nybg.ejpam.v13i2.3634 Email addresses: amornrat.r@psu.ac.th (A. Rattana), ronnason.c@psu.ac.th (R. Chinram) http://www.ejpam.com 200 c© 2020 EJPAM All rights reserved. A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 201 Algebraic systems with one n-ary operation, for n > 2, have been widely investigated (see, e.g., [2, 3, 5, 7]). Algebraic n-ary systems have been applied in several fields of mathematics. The purpose of this paper is to investigate the extension of neutrosophic N -structures in semigroups [4] to n-ary groupoids. Some basic notations and definitions will be pre- sented in section 2. In section 3, we extend the results of neutrosophic N -structures and their applications in semigroups to n-ary groupoids. Section 4 contains a brief summary of this paper. 2. Preliminaries The aim of this section is to review some notations and definitions of n-ary groupoids and neutrosophic N -structures which can be also found in [2–4]. 2.1. n-ary groupoids Definition 1. Let S be a nonempty set. The set S together with an n-ary operation f : Sn → S, where n ≥ 2, is called an n-ary groupoid and is denoted by (S, f). According to the general convention used in the theory of n-ary groupoids, the sequence of elements xi, xi+1, . . . , xj is denoted by xji . In the case j < i, it is the empty symbol. If xi+1 = xi+2 = . . . = xi+t = x, then we write x(t) instead of xi+ti+1. In this convention, f(x1, x2, . . . , xn) = f(xn1 ), and f(x1, . . . , xi, x, . . . , x︸ ︷︷ ︸ t , xi+t+1, . . . , xn) = f(xi1, x (t), xni+t+1). Definition 2. A nonempty subset T of an n-ary groupoids (S, f) is an n-ary subgroupoid of S if (T, f) is an n-ary groupoid, i.e., if it is closed under the operation f . 2.2. Neutrosophic N -structures Definition 3. A neutrosophic N -structure over X is defined to be the structure XN := X (TN , IN , FN ) = { x (TN (x), IN (x), FN (x)) | x ∈ X } where TN , IN and FN are N -functions on X which are called the truth membership func- tion, the indeterminacy membership function and the falsity membership function on X, respectively. Definition 4. Let XN = X (TN , IN , FN ) and XM = X (TM , IM , FM ) be neutrosophic N - structures over X. A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 202 (1) XN is a neutrosophic N -substructure of XM over X, denoted by XN ⊆ XM , if it satisfies the conditions TN (x) ≥ TM (x), IN (x) ≤ IM (x), FN (x) ≥ FM (x) for all x ∈ X. We have that XN ⊆ XM and XM ⊆ XN if and only if XN = XM . (2) The union of XN and XM , denoted it briefly by XN∪M , is defined to be a neutro- sophic N -structure XN∪M = X (TN∪M , IN∪M , FN∪M ) where TN∪M (x) = ∧ {TN (x), TM (x)} , IN∪M (x) = ∨ {IN (x), IM (x)} , FN∪M (x) = ∧ {FN (x), FM (x)} . (3) The intersection of XN and XM , written it simply as XN∩M , is defined to be a neutrosophic N -structure XN∩M = X (TN∩M , IN∩M , FN∩M ) where TN∩M (x) = ∨ {TN (x), TM (x)} , IN∩M (x) = ∧ {IN (x), IM (x)} , FN∩M (x) = ∨ {FN (x), FM (x)} . Definition 5. Let XN := X (TN , IN , FN ) be a neutrosophic N -structure over X. The complement of XN , denoted by XNc, is defined to be a neutrosophic N -structure XNc := X (TNc , INc , FNc) over X, where TNc(x) = −1− TN (x), INc(x) = −1− IN (x), FNc(x) = −1− FN (x) for all x ∈ X. A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 203 Definition 6. Let XN be a neutrosophic N -structure over X and let α, β, γ be real numbers such that α, β, γ ∈ [−1, 0]. Define the sets TαN = {x ∈ X | TN (x) ≤ α}, IβN = {x ∈ X | IN (x) ≥ β}, F γN = {x ∈ X | FN (x) ≤ γ}. We call a set XN (α, β, γ) = {x ∈ X | TN (x) ≤ α, IN (x) ≥ β, FN (x) ≤ γ} an (α, β, γ)-level set of XN . For the convenience, we note that XN (α, β, γ) = TαN ∩ I β N ∩ F γ N . From now on, an n-ary groupoid X denotes the universe of discourse unless otherwise specified. 3. Main results In this section, we will look closely at neutrosophic n-aryN -subgroupoids, the (α, β, γ)- level set, the intersection of neutrosophic n-ary N -subgroupoids, neutrosophic n-ary N - subgroupoid products, ε-neutrosophic n-ary N -subgroupoids, homomorphic preimage of the neutrosophic n-ary N -subgroupoids and onto homomorphic image of the neutrosophic n-ary N -subgroupoids. Definition 7. Let XN := X (TN , IN , FN ) be a neutrosophic structure over an n-ary groupoid X. Then XN is called a neutrosophic n-ary N -subgoupoid of X if the following conditions are valid: TN (f(xn1 )) ≤ ∨ {TN (x1), . . . , TN (xn)}, IN (f(xn1 )) ≥ ∧ {IN (x1), . . . , IN (xn)}, FN (f(xn1 )) ≤ ∨ {FN (x1), . . . , FN (xn)}, for all x1, x2, . . . , xn ∈ X. Theorem 1. Let XN be a neutrosophic n-ary N -subgroupoid of an n-ary groupoid X and let α, β, γ ∈ [−1, 0]. If the (α, β, γ)-level set of XN is nonempty, then it is an n-ary subgroupoid of X. A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 204 Proof. Let x1, . . . , xn ∈ XN (α, β, γ). Then TN (x1) ≤ α, IN (x1) ≥ β, FN (x1) ≤ γ, . . . , TN (xn) ≤ α, IN (xn) ≥ β, FN (xn) ≤ γ. It follows that TN (f(xn1 )) ≤ ∨ {TN (x1), . . . , TN (xn)} ≤ α, IN (f(xn1 )) ≥ ∧ {IN (x1), . . . , IN (xn)} ≥ β, FN (f(xn1 )) ≤ ∨ {FN (x1), . . . , FN (xn)} ≤ γ. Therefore f(xn1 ) ∈ XN (α, β, γ). This implies that XN (α, β, γ) is an n-ary subgroupoid of X. Theorem 2. Let XN be a neutrosophic N -structure over an n-ary groupoid X. If TαN , I β N and F γN are n-ary subgroupoids of X for all α, β, γ ∈ [−1, 0], then XN is a neutrosophic n-ary N -subgroupoid of X. Proof. We prove this theorem by contradiction. Assume that there exist x1, . . . , xn ∈ X such that TN (f(xn1 )) > ∨ {TN (x1), . . . , TN (xn)}. Then TN (f(xn1 )) > tα ≥ ∨ {TN (x1), . . . , TN (xn)} for some tα ∈ [−1, 0). Thus x1, . . . , xn ∈ T tαN but f(xn1 ) /∈ T tαN , which is a contradiction. Thus TN (f(xn1 )) ≤ ∨ {TN (x1), . . . , TN (xn)} for all x1, . . . , xn ∈ X. We now assume that IN (f(xn1 )) < ∨ {IN (x1), . . . , IN (xn)} for some x1, . . . , xn ∈ X. Then IN (f(xn1 )) < tβ ≤ ∨ {IN (x1), . . . , IN (xn)} for some tβ ∈ [−1, 0). Thus x1, . . . , xn ∈ I tβ N but f(xn1 ) /∈ I tβ N . This is a contradiction. Hence IN (f(xn1 )) ≥ ∧ {IN (x1), . . . , IN (xn)} for all x1, . . . , xn ∈ X. It remains to prove that FN (f(xn1 )) ≤ ∨ {FN (x1), . . . , FN (xn)} for all x1, . . . , xn ∈ X. Suppose contrary to our claim that there are x1, . . . , xn ∈ X such that FN (f(xn1 )) > ∨ {FN (x1), . . . , FN (xn)}. Then FN (f(xn1 )) > tγ ≥ ∨ {FN (x1), . . . , FN (xn)} for some tγ ∈ [−1, 0). Thus x1, . . . , xn ∈ F tγ N but f(xn1 ) /∈ F tγN , which is a contradiction. Therefore XN is a neutrosophic n-ary N -subgroupoid of X. A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 205 Theorem 3. Let XN := X (TN , IN , FN ) and XM := X (TM , IM , FM ) be two neutrosophic n-ary N -subgroupoids over X. Then XN∩M is also a neutrosophic n-ary N -subgroupoid of X. Proof. Let x1, . . . , xn ∈ X. We obtain TN∩M (f(xn1 )) = ∨ {TN (f(xn1 )), TM (f(xn1 ))} ≤ ∨{∨ {TN (x1), . . . , TN (xn)} , ∨ {TM (x1), . . . , TM (xn)} } = ∨{∨ {TN (x1), TM (x1)} , . . . , ∨ {TN (xn), TM (xn)} } = ∨ {TN∩M (x1), . . . , TN∩M (xn)} , IN∩M (f(xn1 )) = ∧ {IN (f(xn1 )), IM (f(xn1 ))} ≥ ∧ {∧ {IN (x1), . . . , IN (xn)} , ∧ {IM (x1), . . . , IM (xn)} } = ∧ {∧ {IN (x1), IM (x1)} , . . . , ∧ {IN (xn), IM (xn)} } = ∧ {IN∩M (x1), . . . , IN∩M (xn)} , FN∩M (f(xn1 )) = ∨ {FN (f(xn1 )), FM (f(xn1 ))} ≤ ∨{∨ {FN (x1), . . . , FN (xn)} , ∨ {FM (x1), . . . , FM (xn)} } = ∨{∨ {FN (x1), FM (x1)} , . . . , ∨ {FN (xn), FM (xn)} } = ∨ {FN∩M (x1), . . . , FN∩M (xn)} for all x1, . . . , xn ∈ X. Therefore XN∩M is a neutrosophic n-ary N -subgroupoid of X. Corollary 1. Let {XNi | i ∈ N} be a family of neutrosophic n-ary N -subgroupoids of an n-ary groupoid X.Then ⋂ i∈NXNi is also a neutrosophic n-ary N -subgroupoid of X. For each i ∈ {1, 2, . . . , n}, let XNi := X (TNi , INi , FNi) be a neutrosophic N -structure over an n-ary groupoid (X, f). Then a neutrosophic N -structure over X XN1 � . . .�XNn = X (TN1 � . . .� TNn , IN1 � . . .� INn , FN1 � . . .� FNn) = { x TN1 � . . .� TNn(x), IN1 � . . .� INn(x), FN1 � . . .� FNn(x) ∣∣∣x ∈ X} is defined to be a neutrosophic N -product of XN1 , XN2 , . . . , XNn where TN1�. . .�TNn(x) =  ∧ x=f(xn1 ) {TN1(x1) ∨ ... ∨ TNn(xn)} , if x = f(xn1 ) ∃x1, ..., xn ∈ X, 0, otherwise, A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 206 IN1 � . . .� INn(x) =  ∨ x=f(xn1 ) {IN1(x1) ∧ ... ∧ INn(xn)} , if x = f(xn1 ) ∃x1, ..., xn ∈ X, −1, otherwise, and FN1�. . .�FNn(x) =  ∧ x=f(xn1 ) {FN1(x1) ∨ ... ∨ FNn(xn)} , if x = f(xn1 ) ∃x1, ..., xn ∈ X, 0, otherwise. If XN = XN1 = XN2 = . . . = XNn , then XN1 � . . .�XNn is denoted by �(XN )(n). For any x ∈ X, the element x �(TN )(n)(x),�(IN )(n)(x),�(FN )(n)(x) is denoted by �(XN )(n)(x) := ( �(TN )(n)(x),�(IN )(n)(x),�(FN )(n)(x) ) . Theorem 4. A neutrosophic N -structure XN over X is a neutrosophic N -subgroupoid of X if and only if �(XN )(n) ⊆ XN . Proof. We first prove that if a neutrosophic N -structure XN over X is a neutrosophic n-ary N -subgroupoid of X, then �(XN )(n) ⊆ XN . We assume that XN is a neutrosophic n-ary N -subgroupoid of X and let x ∈ X. If x 6= f(xn1 ) for all x1, . . . , xn ∈ X, then this clearly forces �(XN )(n) ⊆ XN . Suppose that there are x1, . . . , xn ∈ X such that x = f(xn1 ), we obtain �(TN )(n)(x) = ∧ x=f(xn1 ) {TN (x1) ∨ . . . ∨ TN (xn)} ≥ ∧ x=f(xn1 ) TN (f(xn1 )) = TN (x), �(IN )(n)(x) = ∨ x=f(xn1 ) {IN (x1) ∧ . . . ∧ IN (xn)} ≤ ∨ x=f(xn1 ) IN (f(xn1 )) = IN (x), �(FN )(n)(x) = ∧ x=f(xn1 ) {FN (x1) ∨ . . . ∨ FN (xn)} ≥ ∧ x=f(xn1 ) FN (f(xn1 )) = FN (x). Therefore �(XN )(n) ⊆ XN . Conversely, letXN be any neutrosophic n-aryN -subgroupoid ofX such that�(XN )(n) ⊆ XN . We only need to show that XN is a neutrosophic n-ary N -subgroupoid of X. Let x1, . . . , xn be elements of X and let x = f(xn1 ). Then TN (f(xn1 )) = TN (x) ≤ �(TN )(n)(x) = ∧ x=f(xn1 ) {TN (x1) ∨ . . . ∨ TN (xn)} ≤ TN (x1) ∨ . . . ∨ TN (xn), IN (f(xn1 )) = IN (x) ≥ �(IN )(n)(x) = ∨ x=f(xn1 ) {IN (x1) ∧ . . . ∧ IN (xn)} ≥ IN (x1) ∧ . . . ∧ IN (xn), A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 207 FN (f(xn1 )) = FN (x) ≤ �(FN )(n)(x) = ∧ x=f(xn1 ) {FN (x1) ∨ . . . ∨ FN (xn)} ≤ FN (x1) ∨ . . . ∨ FN (xn). Therefore XN is a neutrosophic n-ary N -subgroupoid of X. Theorem 5. Let X be an n-ary groupoid with identity e and let XN := X (TN , IN , FN ) be a neutrosophic n-ary N -subgroupoid over X such that XN (e) ≥ XN (x) for all x ∈ X, that is, TN (e) ≤ TN (x), IN (e) ≥ IN (x) and FN (e) ≤ FN (x) for all x ∈ X. If XN is a neutrosophic n-ary N -subgroupoid of X, then �(XN )(n) = XN . Proof. For any x ∈ X, we have �(TN )(n)(x) = ∧ x=f(xn1 ) {TN (x1) ∨ . . . ∨ TN (xn)} ≤ TN (x) ∨ TN (e) = TN (x), �(IN )(n)(x) = ∨ x=f(xn1 ) {IN (x1) ∧ . . . ∧ IN (xn)} ≥ IN (x) ∧ IN (e) = IN (x), �(FN )(n)(x) = ∧ x=f(xn1 ) {FN (x1) ∨ . . . ∨ FN (xn)} ≤ FN (x) ∨ FN (e) = FN (x). This shows that XN ⊆ �(XN )(n). From Theorem 4, we already have �(XN )(n) ⊆ XN . Then �(XN )(n) = XN . Definition 8. A neutrosophic N -structure XN over X is said to be an ε-neutrosophic n-ary N -subgroupoid of X if the conditions TN (f(xn1 )) ≤ ∨ {TN (x1), . . . , TN (xn), εT } , IN (f(xn1 )) ≥ ∧ {IN (x1), . . . , IN (xn), εI} , FN (f(xn1 )) ≤ ∨ {FN (x1), . . . , FN (xn), εF } , hold for all x1, . . . , xn ∈ X where εT , εI , εF ∈ [−1, 0]. Proposition 1. Let XN be an ε-neutrosophic n-ary N -subgroupoid of X. If XN (x) ≤ (εT , εI , εF ), that is, TN (x) ≥ εT , IN (x) ≤ εI , FN (x) ≥ εF for all x ∈ X, then XN is a neutrosophic n-ary N -subgroupoid of X. Theorem 6. Let XN be a neutrosophic N -structure over X and let α, β, γ be real numbers on the interval [−1, 0]. If XN is an ε-neutrosophic n-ary N -subgroupoid of X, then the (α, β, γ)-level set of XN is an n-ary subgroupoid of X whenever (α, β, γ) ≤ (εT , εI , εF ), that is α ≥ εT , β ≤ εI , and γ ≥ εF . A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 208 Proof. Assume that XN (α, β, γ) 6= ∅ for α, β, γ ∈ [−1, 0]. Let x1, . . . , xn ∈ XN (α, β, γ). Then TN (x1) ≤ α, IN (x1) ≥ β, FN (x1) ≤ γ, . . . , TN (xn) ≤ α, IN (xn) ≥ β, FN (xn) ≤ γ. It follows that TN (f(xn1 )) ≤ ∨ {TN (x1), . . . , TN (xn), εT } ≤ ∨ {α, εT } = α, IN (f(xn1 )) ≥ ∧ {IN (x1), . . . , IN (xn), εI} ≥ ∧ {β, εI} = β, FN (f(xn1 )) ≤ ∨ {FN (x1), . . . , FN (xn), εF } ≤ ∨ {γ, εF } = γ. Hence f(xn1 ) ∈ XN (α, β, γ). It follows that XN (α, β, γ) is an n-ary subgroupoid of X. Theorem 7. Let XN be a neutrosophic N -structure over X and let α, β, γ be real numbers on the interval [−1, 0]. If TαN , I β N and F γN are n-ary subgroupoids of X for all εT , εI , εF ∈ [−1, 0] and (α, β, γ) ≤ (εT , εI , εF ), then XN is an ε-neutrosophic n-ary N -subgroupoid of X. Proof. We prove this theorem by contradiction. We begin the proof by assuming that TN (f(xn1 )) > ∨ {TN (x1), . . . , TN (xn), εT } . for some x1, . . . , xn ∈ X. Then TN (f(xn1 )) > tα ≥ ∨ {TN (x1), . . . , TN (xn), εT } for some tα ∈ [−1, 0). It follows that x1, . . . , xn ∈ T tαN , f(xn1 ) /∈ T tαN and tα ≥ εT . This is a contradiction since T tαN is an n-ary subgroupoid of X by hypothesis. Thus TN (f(xn1 )) ≤ ∨ {TN (x1), . . . , TN (xn), εT } for all x1, . . . , xn ∈ X. Suppose now that there are x1, . . . , xn ∈ X such that IN (f(xn1 )) < ∧ {IN (x1), . . . , IN (xn), εI} . Then IN (f(xn1 )) < tβ ≤ ∧ {IN (x1), . . . , IN (xn), εI} for some tβ ∈ [−1, 0). It follows that x1, . . . , xn ∈ I tβ N , f(xn1 ) /∈ I tβ N and tβ ≤ εI . This contradicts to the fact that I tβ N is an n-ary subgroupoid of X. Thus IN (f(xn1 )) ≥ ∧ {IN (x1), . . . , IN (xn), εI} for all x1, . . . , xn ∈ X. Similarly, assume that FN (f(xn1 )) > ∨ {FN (x1), . . . , FN (xn), εF } A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 209 for some x1, . . . , xn ∈ X. Then FN (xn1 ) > tγ ≥ ∨ {FN (x1), . . . , FN (xn), εF } for some tγ ∈ [−1, 0). It implies that x1, . . . , xn ∈ F tγ N , f(xn1 ) /∈ F tγN and tγ ≥ εF . This is a contradiction since F tγ N is an n-ary subgroupoid of X. Thus FN (f(xn1 )) ≤ ∨ {FN (x1), . . . , FN (xn), εF } for all x1, . . . , xn ∈ X. Therefore XN is an ε-neutrosophic n-ary N -subgroupoid of X. Theorem 8. Let εT , εI , εF , δT , δI , δF ∈ [−1, 0]. Let XN and XM be an ε-neutrosophic n-ary N -subgroupoid and a δ-neutrosophic n-ary N -subgroupoid of X, respectively. The intersection of XN and XM is a ξ-neutrosophic n-ary N -subgroupoid of X for ξ := ε ∧ δ where (ξT , ξI , ξF ) = (εT ∨ δT , εI ∧ δI , εF ∨ δF ). Proof. For any x1, . . . , xn ∈ X, we have TN∩M (f(xn1 )) = ∨ {TN (f(xn1 )), TM (f(xn1 ))} ≤ ∨{∨ {TN (x1), . . . , TN (xn), εT } , ∨ {TM (x1), . . . , TM (xn), δT } } ≤ ∨{∨ {TN (x1), . . . , TN (xn), ξT } , ∨ {TM (x1), . . . , TM (xn), ξT } } = ∨{∨ {TN (x1), TM (x1), ξT } , . . . , ∨ {TN (xn), TM (xn), ξT } } = ∨{∨ {TN (x1), TM (x1)} , . . . , ∨ {TN (xn), TM (xn)} , ξT } = ∨ {TN∩M (x1), . . . , TN∩M (xn), ξT } , IN∩M (f(xn1 )) = ∧ {IN (f(xn1 )), IM (f(xn1 ))} ≥ ∧{∧ {IN (x1), . . . , IN (xn), εI} , ∧ {IM (x1), . . . , IM (xn), δI} } ≥ ∧{∧ {IN (x1), . . . , IN (xn), ξI} , ∧ {IM (x1), . . . , IM (xn), ξI} } = ∧{∧ {IN (x1), IM (x1), ξI} , . . . , ∧ {IN (xn), IM (xn), ξI} } = ∧{∧ {IN (x1), IM (x1)} , . . . , ∧ {IN (xn), IM (xn)} , ξI } = ∧ {IN∩M (x1), . . . , IN∩M (xn), ξI} , FN∩M (f(xn1 )) = ∨ {FN (f(xn1 )), FM (f(xn1 ))} ≤ ∨{∨ {FN (x1), . . . , FN (xn), εF } , ∨ {FM (x1), . . . , FM (xn), δF } } ≤ ∨{∨ {FN (x1), . . . , FN (xn), ξF } , ∨ {FM (x1), . . . , FM (xn), ξF } } = ∨{∨ {FN (x1), FM (x1), ξF } , . . . , ∨ {FN (xn), FM (xn), ξF } } A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 210 = ∨{∨ {FN (x1), FM (x1)} , . . . , ∨ {FN (xn), FM (xn)} , ξF } = ∨ {FN∩M (x1), . . . , FN∩M (xn), ξF } . Therefore XN∩M is a ξ-neutrosophic n-ary N -subgroupoid of X. Theorem 9. Let XN be an ε-neutrosophic n-ary N -subgroupoid of X. If κ := (κT , κI , κF ) = (∨ x∈X {TN (x)}, ∧ x∈X {IN (x)}, ∨ x∈X {FN (x)} ) then the set Ω := {x ∈ X | TN (x) ≤ κT ∨ εT , IN (x) ≥ κI ∧ εI , FN (x) ≤ κF ∨ εF } is an n-ary subgroupoid of X. Proof. Let x1, . . . , xn ∈ Ω for any x1, . . . , xn ∈ X. Then TN (x1) ≤ κT ∨ εT = ∨ x1∈X {TN (x1)} ∨ εT , IN (x1) ≥ κI ∧ εI = ∧ x1∈X {IN (x1)} ∧ εI , FN (x1) ≤ κF ∨ εF = ∨ x1∈X {FN (x1)} ∨ εF , ... TN (xn) ≤ κT ∨ εT = ∨ xn∈X {TN (xn)} ∨ εT , IN (xn) ≥ κI ∧ εI = ∧ xn∈X {IN (xn)} ∧ εI , FN (xn) ≤ κF ∨ εF = ∨ xn∈X {FN (xn)} ∨ εF . It follows that TN (f(xn1 )) ≤ ∨ {TN (x1), . . . , TN (xn), εT } ≤ ∨ {κT ∨ εT , . . . , κT ∨ εT , εT } = κT ∨ εT , IN (f(xn1 )) ≥ ∧ {IN (x1), . . . , IN (xn), εI} ≥ ∧ {κI ∧ εI , . . . , κI ∧ εI , εI} = κI ∧ εI , A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 211 FN (f(xn1 )) ≤ ∨ {FN (x1), . . . , FN (xn), εF } ≤ ∨ {κF ∨ εF , . . . , κF ∨ εF , εF } = κF ∨ εF , Then f(xn1 ) ∈ Ω. Hence Ω is an n-ary subgroupoid of X. Let X and Y be sets, g : X → Y be a function, YN := Y (TN , IN , FN ) be a neutrosophic N -structure over Y with ε = (εT , εI , εF ). An ε-neutrosophic N -structure over X is defined by Xε N := X (T εN , I ε N , F ε N ) where T εN : X → [−1, 0], x 7→ ∨{TN (g(x)), εT }, IεN : X → [−1, 0], x 7→ ∧{IN (g(x)), εI}, F εN : X → [−1, 0], x 7→ ∨{FN (g(x)), εF }. Theorem 10. Let X,Y be two n-ary groupoids and g : X → Y be a homomorphism. If a neutrosophic N -structure YN := Y (TN , IN , FN ) over Y is an ε-neutrosophic n-ary N - subgroupoid of Y , then Xε N := X (T εN , I ε N , F ε N ) is an ε-neutrosophic n-ary N -subgroupoid of X. Proof. For any x1, . . . , xn ∈ X, we have T εN (f(xn1 )) = ∨ {TN (g(f(xn1 ))), εT } = ∨ {TN (g(x1) . . . g(xn)), εT } ≤ ∨ { ∨ {TN (g(x1)), . . . , TN (g(xn)), εT }, εT } = ∨ { ∨ {TN (g(x1)), εT }, . . . , ∨ {TN (g(xn)), εT }, εT } = ∨ {T εN (x1), . . . , T ε N (xn), εT }, IεN (f(xn1 )) = ∧ {IN (g(f(xn1 ))), εI} = ∧ {IN (g(x1) . . . g(xn)), εI} ≥ ∧ { ∧ {IN (g(x1)), . . . , IN (g(xn)), εI}, εI} = ∧ { ∧ {IN (g(x1)), εI}, . . . , ∧ {IN (g(xn)), εI}, εI} = ∧ {IεN (x1), . . . , I ε N (xn), εI}, F εN (f(xn1 )) = ∨ {FN (g(f(xn1 ))), εF } = ∨ {FN (g(x1) . . . g(xn)), εF } A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 212 ≤ ∨ { ∨ {FN (g(x1)), . . . , FN (g(xn)), εF }, εF } = ∨ { ∨ {FN (g(x1)), εF }, . . . , ∨ {FN (g(xn)), εF }, εF } = ∨ {F εN (x1), . . . , F ε N (xn), εF }. Therefore Xε N := X (T εN , I ε N , F ε N ) is an ε-neutrosophic n-ary N -subgroupoid of X. Let X,Y be two sets and g : X → Y be a function. If YM := Y (TM , IM , FM ) is a neutrosophic N -structure over Y , then the preimage of YM under g is a neutrosophic N -structure over X defined by g−1(YM ) := X (g−1(TM ), g−1(IM ), g−1(FM )) where g−1(TM )(x) = TM (g(x)), g−1(IM )(x) = IM (g(x)), and g−1(FM )(x) = FM (g(x)) for all x ∈ X. Theorem 11. Let X,Y be two n-ary groupoids and g : X → Y be a homomorphism. If YM := Y (TM , IM , FM ) is a neutrosophic n-ary N -subgroupoid of Y , then the preimage of YM under g, g−1(YM ) = X (g−1(TM ), g−1(IM ), g−1(FM )) , is a neutrosophic n-ary N -subgroupoid of X. Proof. For any x1, . . . , xn ∈ X, we have g−1(TM )(f(xn1 )) = TM (g(f(xn1 ))) = TM (g(x1) . . . g(xn)) ≤ ∨ {TM (g(x1)), . . . , TM (g(xn))} = ∨{ g−1(TM )(x1), . . . , g −1(TM )(xn) } , g−1(IM )(f(xn1 )) = IM (g(f(xn1 ))) = IM (g(x1) . . . g(xn)) ≥ ∧ {IM (g(x1)), . . . , IM (g(xn))} = ∧{ g−1(IM )(x1), . . . , g −1(IM )(xn) } , g−1(FM )(f(xn1 )) = FM (g(f(xn1 ))) = FM (g(x1) . . . g(xn)) ≤ ∨ {FM (g(x1)), . . . , FM (g(xn))} = ∨{ g−1(FM )(x1), . . . , g −1(FM )(xn) } . Therefore g−1(YM ) is a neutrosophic n-ary N -subgroupoid of X. A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 213 Let X,Y be two sets and g : X → Y be an onto function. If XN := X (TN , IN , FN ) is a neutrosophic N -structure over X, then the image of XN under g is a neutrosophic N -structure over Y defined by g(XN ) := Y (g(TN ), g(IN ), g(FN )) where g(TN )(y) = ∧ x∈g−1(y) TN (x), g(IN )(y) = ∨ x∈g−1(y) IN (x), g(FN )(y) = ∧ x∈g−1(y) FN (x). Theorem 12. Let X,Y be two n-ary groupoids and let g : X → Y be an onto homo- morphism. Let XN := X (TN , IN , FN ) be a neutrosophic N -structure of X such that for all A ⊆ X, there is x0 ∈ A such that TN (x0) = ∧ z∈A TN (z), IN (x0) = ∨ z∈A IN (z), FN (x0) = ∧ z∈A FN (z). If XN is a neutrosophic n-ary N -subgroupoid of X, then the image of XN under g, g(XN ) = Y (g(TN ), g(IN ), g(FN )) , is a neutrosophic n-ary N -subgroupoid of Y . Proof. Let g(XN ) = Y (g(TN ), g(IN ), g(FN )) be the image of XN under g. Let y1, . . . , yn ∈ Y . Then g−1(y1) 6= ∅, . . . , , g−1(yn) 6= ∅ in X which implies that there are xy1 ∈ g−1(y1), . . . , xyn ∈ g−1(yn) such that TN (xy1) = ∧ z1∈g−1(y1) TN (z1), IN (xy1) = ∨ z1∈g−1(y1) IN (z1), FN (xy1) = ∧ z1∈g−1(y1) FN (z1), ... TN (xyn) = ∧ zn∈g−1(yn) TN (zn), IN (xyn) = ∨ zn∈g−1(yn) IN (zn), FN (xyn) = ∧ zn∈g−1(yn) FN (zn). A. Rattana, R. Chinram / Eur. J. Pure Appl. Math, 13 (2) (2020), 200-215 214 Hence g(TN )(yn1 ) = ∧ x∈g−1(yn1 ) TN (x) ≤ TN (xy1 . . . xyn) ≤ ∨ {TN (xy1), . . . , TN (xyn)} = ∨ ∧ z1∈g−1(y1) TN (z1), . . . , ∧ zn∈g−1(yn) TN (zn)  = ∨ {g(TN )(y1), . . . , g(TN )(yn)} , g(IN )(yn1 ) = ∨ x∈g−1(yn1 ) IN (x) ≥ IN (xy1 . . . xyn) ≥ ∧ {IN (xy1), . . . , IN (xyn)} = ∧ ∨ z1∈g−1(y1) IN (z1), . . . , ∨ zn∈g−1(yn) IN (zn)  = ∧ {g(IN )(y1), . . . , g(IN )(yn)} , g(FN )(yn1 ) = ∧ x∈g−1(yn1 ) FN (x) ≤ FN (xy1 . . . xyn) ≤ ∨ {FN (xy1), . . . , FN (xyn)} = ∨ ∧ z1∈g−1(y1) FN (z1), . . . , ∧ zn∈g−1(yn) FN (zn)  = ∨ {g(FN )(y1), . . . , g(FN )(yn)} . Hence g(XN ) is a neutrosophic n-ary N -subgroupoid of Y . 4. Conclusions We have studied the neutrosophic N -structure and applied it to n-ary groupoids. We also investigated the notion of neutrosophic N -structures in n-ary groupoids and showed some properties. We have investigated the conditions for neutrosophic N -structures to be neutrosophic n-ary N -subgroupiods. 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