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Neutrosophic Sets and Systems, Vol. 35, 2020 University of New Mexico Basic operations on hypersoft sets and hypersoft point Mujahid Abbas 1, Ghulam Murtaza 2,* and Florentin Smarandache 3 1 Department of Mathematics, Government College University, Lahore 54000, Pakistan and Department of Mathematics and Applied Mathematics,, University of Pretoria, Lynnwood Road, Pretoria 0002, South Africa; [email protected], 2Department of Mathematics, University of Management Technology, Lahore, 54000, Pakistan; [email protected] 2 University of New Mexico, USA; [email protected]; [email protected] * Correspondence: [email protected] Abstract: The aim of this paper is to initiat formal study of hypersoft sets. We first, present basic operations like union, intersection and difference of hypersoft sets; basic ingrediants for topological structures on the collection of hypersoft sets. Moreover we introduce hypersoft points in different envorinments like fuzzy hypersoft set, intuitionistic fuzzy hypersoft set, neutrosophic hypersoft, plithogenic hypersoft set, and give some basic properties of hypersoft points in these envorinments. We expect that this will constitue an appropriate framework of hypersoft functions and the study of hypersoft function spaces. Examples are provided to explain the newly defined concepts. Keywords: soft set; hypersoft set; set operations on hypersoft sets; hypersoft point; fuzzy hypersoft set; intuitionistic fuzzy hypersoft set; neutrosophic hypersoft; plithogenic hypersoft set. 1. Introduction Molodtsov [16] defined soft set as a mathematical tool to deal with uncertainties associated with real world problems. Soft set theory has application in decision making, demand analysis, forecasting, information sciences and other disciplines (see for example, [ 13, 14, 15, 17, 18, 19, 20, 21, 22, 23]). Plithogenic and neutrosophic hypersoft sets theory is being applied successfully in decision making problems (see, [2, 3, 4, 5, 6, 7, 8, 9,10,11,12]). By definition, a soft set can be identified by a pair (𝐹,𝐴), where 𝐹 stands for a multivalued function defined on the set of parameters 𝐴. Smarandache [1] extended the notion of a soft set to the hypersoft set by replacing the function 𝐹 with a multi-argument function defined on the Cartesian product of 𝑛 different set of parameters. This concept is more flexible than soft set and more suitable in the context of decision making problems. We expect the notion of hypersoft set will attract the attention of researchers working on soft set theory and its diverse applications. The purpose of this paper is to initiate a formal investigation in this new area of research. As a first step, we present the basic operations like union, intersection and difference of hypersoft sets. Moreover we introduce hypersoft points and some basic properties of these points Mujahid Abbas, Ghulam Murtaza, and Florentin Smarandache, Basic operations on hypersoft sets and hypersoft point Neutrosophic Sets and Systems, Vol. 35, 2020 408 which may provide the foundation for the hypersoft functions and hence the hypersoft fixed point theory. 2. Operations on hypersoft sets In this section, we define basic operations on hypersoft sets. Smarandache defined the hypersoft set in the following manner: Definition 1 [1] Let π‘ˆ be a universe of discourse, 𝑃(π‘ˆ) the power set π‘ˆ and 𝐸 ,𝐸 ,…,𝐸 the pairwise 1 2 𝑛 disjoint sets of parameters. Let 𝐴 be the nonempty subset of 𝐸 for each 𝑖 =1,2,...,𝑛. A hypersoft set can be 𝑖 𝑖 identified by the pair (𝐹,𝐴 ×𝐴 ×⋯×𝐴 ), where: 1 2 𝑛 𝐹:𝐴 ×𝐴 ×⋯×𝐴 →𝑃(π‘ˆ). 1 2 𝑛 For sake of simplicity, we write the symbols 𝐄 for 𝐸 ×𝐸 ×⋯×𝐸 , 𝐀 for 𝐴 ×𝐴 ×⋯×𝐴 and 1 2 𝑛 1 2 𝑛 𝛂 for an element of the set 𝐀. We also suppose that none of the set 𝐴 is empty. 𝑖 Definition 2 [1] A hypersoft set; on a crisp universe of discourse π‘ˆ is called Crisp Hypersoft set (or simply "hypersoft set"); 𝐢 on a fuzzy universe of discourse π‘ˆ is called Fuzzy Hypersoft set. 𝐹 on a Intuitionistic Fuzzy universe of discourse π‘ˆ is called Intuitionistic Fuzzy Hypersoft set; 𝐼𝐹 on a Neutrosophic universe of discourse π‘ˆ is called Neutrosophic Hypersoft Set; 𝑁 on a Plithogenic universe of discourse π‘ˆ is called Plithogenic Hypersoft Set. 𝑃 The nature of 𝐹(𝛂) is determined by the nature of universe of discourse. Therefore 𝑃(π‘ˆ) depends upon the nature of universe. We denote β„‹(π‘ˆ ,𝐄) by the family of all *-hypersoft sets over βˆ— (π‘ˆ ,𝐄), where βˆ— can take any value in the set {𝐢,𝐹,𝐼𝐹,𝑁,𝑃}, where symbols 𝐢,𝐹,𝐼𝐹,𝑁,𝑃 denote βˆ— Crisp, Fuzzy, Intuitionistic Fuzzy, Neutrosophic, and Plithogenic sets, respectively. The following are the basic operations on *-hypersoft set. Definition 3 Let π‘ˆ be a universe of discourse and 𝑨 a subset of 𝑬. Then (𝐹,𝑨) is called βˆ— 1. a null *-hypersoft set if for each parameter πœΆβˆˆπ‘¨, 𝐹(𝜢) is an 0 . We will denote it by 𝛷 . βˆ— 𝑨 2. an absolute *-hypersoft set if for each parameter πœΆβˆˆπ‘¨, 𝐹(𝜢)=π‘ˆ . We will denote it by π‘ˆΜƒ . βˆ— 𝑨 π‘₯ π‘₯ Remark 1 We consider 0 =βŒ€ for empty set, 0 ={ ,π‘₯ βˆˆπ‘ˆ } for null fuzzy set, 0 ={ ,π‘₯ βˆˆπ‘ˆ } 𝐢 𝐹 0 𝐹 𝐼𝐹 <0,1> 𝐼𝐹 π‘₯ for null intuitionistic fuzzy set, 0 ={ ,π‘₯ βˆˆπ‘ˆ } for null neutrosophic set. However, in case of 𝑁 <0,1,1> 𝑁 plithogenic set, we have the following notations: β€’ Null plithgenic crisp set 0 ={π‘₯(0,0,...,0),forallπ‘₯ βˆˆπ‘ˆ }. 𝑃𝐢 𝑃 β€’ Universal plithgenic crisp set 1 ={π‘₯(1,1,...,1),forallπ‘₯ βˆˆπ‘ˆ }. 𝑃𝐢 𝑃 Note that null plithgenic fuzzy set will be same as null plithgenic crisp set and universal plithgenic fuzzy set will be the same as universal plithgenic crisp set. Mujahid Abbas, Ghulam Murtaza, and Florentin Smarandache, Basic operations on hypersoft sets and hypersoft point Neutrosophic Sets and Systems, Vol. 35, 2020 409 β€’ Null plithgenic intuitionistic fuzzy set 0 ={π‘₯((0,1),(0,1),...,(0,1)),forallπ‘₯ βˆˆπ‘ˆ }. 𝑃𝐼𝐹 𝑃 β€’ Universal plithgenic intuitionistic fuzzy set 1 ={π‘₯((1,0),(1,0),...,(1,0)),forallπ‘₯ βˆˆπ‘ˆ }. 𝑃𝐼𝐹 𝑃 β€’ Null plithgenic neutrosophic set 0 ={π‘₯((0,1,1),(0,1,1),...,(0,1,1)),forallπ‘₯ βˆˆπ‘ˆ }. 𝑃𝑁 𝑃 β€’ Universal plithgenic neutrosophic set 1 ={π‘₯((1,0,0),(1,0,0),...,(1,0,0)),forallπ‘₯ βˆˆπ‘ˆ}. 𝑃𝑁 Definition 4 Let (𝐹,𝑨) and (𝐺,𝑩) be two *-hypersoft sets over π‘ˆ . Then union of (𝐹,𝑨) and (𝐺,𝑩) is βˆ— denoted by (𝐻,π‘ͺ)=(𝐹,𝑨)βˆͺΜƒ(𝐺,𝑩) with π‘ͺ=𝐢 ×𝐢 ×⋯×𝐢 , where 𝐢 =𝐴 βˆͺ𝐡 for 𝑖 =1,2,...,𝑛, 1 2 𝑛 𝑖 𝑖 𝑖 and 𝐻 is defined by 𝐹(𝛂), ifπ›‚βˆˆπ€βˆ’π 𝐺(𝛂), ifπ›‚βˆˆπβˆ’π€ 𝐻(𝛂)=( 𝐹(𝛂)βˆͺ 𝐺(𝛂), ifπ›‚βˆˆπ€βˆ©π, βˆ— 0 , else, βˆ— where 𝛂=(𝑐 ,𝑐 ,...,𝑐 )∈𝐢. 1 2 𝑛 Remark 2 Note that, in the case of union of two hypersoft sets the set of parameters is a Cartesian product of sets of parameters whereas in the case of union of two soft sets the set of parameter is just the union of sets of parameters. Definition 5 Let (𝐹,𝑨) and (𝐺,𝑩) be two *-hypersoft sets over π‘ˆ . Then intersection of (𝐹,𝑨) and (𝐺,𝑩) βˆ— is denoted by (𝐻,π‘ͺ)=(𝐹,𝑨)βˆ©Μƒ(𝐺,𝑩), where π‘ͺ=𝐢 ×𝐢 ×⋯×𝐢 is such that 𝐢 =𝐴 ∩𝐡 for 𝑖 = 1 2 𝑛 𝑖 𝑖 𝑖 1,2,...,𝑛 and 𝐻 is defined as 𝐻(𝛂)=𝐹(𝛂)∩ 𝐺(𝛂), βˆ— where 𝜢=(𝑐 ,𝑐 ,...,𝑐 )∈π‘ͺ. If 𝐢 is an empty set for some 𝑖, then (𝐹,𝑨)βˆ©Μƒ(𝐺,𝑩) is defined to be a null 1 2 𝑛 𝑖 *-hypersoft set. Definition 6 Let (𝐹,𝑨) and (𝐺,𝑩) be two *-hypersoft sets over π‘ˆ . Then (𝐹,𝑨) is called a *-hypersoft βˆ— subset of (𝐺,𝑩) if π‘¨βŠ†π‘©, and 𝐹(𝜢)βŠ† 𝐺(𝜢) for all πœΆβˆˆπ‘¨. We denote this by (𝐹,𝑨)βŠ†Μƒ (𝐺,𝑩). Thus (𝐹,𝑨) βˆ— and (𝐺,𝑩) are said to equal if (𝐹,𝑨)βŠ†Μƒ (𝐺,𝑩) and (𝐹,𝑨)βŠ‡Μƒ (𝐺,𝑩). Definition 7 Let (𝐹,𝑨) and (𝐺,𝑩) be two *-hypersoft sets over π‘ˆ . Then *-hypersoft difference of (𝐹,𝑨) βˆ— and (𝐺,𝑩), denoted by (𝐻,π‘ͺ)=(𝐹,𝑨)\Μƒ(𝐺,𝑩), where π‘ͺ=𝐢 ×𝐢 ×⋯×𝐢 is such that 𝐢 =𝐴 ∩𝐡 for 1 2 𝑛 𝑖 𝑖 𝑖 𝑖 =1,2,...,𝑛, and 𝐻 is defined by 𝐻(𝛂)=𝐹(𝛂)\ 𝐺(𝛂), βˆ— where 𝛂=(𝑐 ,𝑐 ,...,𝑐 )βˆˆπ‚. If 𝐢 is an empty set for some 𝑖 then (𝐹,𝐀)\Μƒ(𝐺,𝐁) is defined to be 1 2 𝑛 𝑖 (𝐹,𝐀). Definition 8 The complement of a *-hypersoft set (𝐹,𝑨) is denoted as (𝐹,𝑨)𝑐 and is defined by (𝐹,𝑨)𝑐 = (𝐹𝑐,𝑨) where 𝐹𝑐(𝜢) is the *-complemet of 𝐹(𝜢) for each πœΆβˆˆπ‘¨. Example 1 Let U={x ,x ,x ,x }. Define the attributes sets by: 1 2 3 4 Mujahid Abbas, Ghulam Murtaza, and Florentin Smarandache, Basic operations on hypersoft sets and hypersoft point Neutrosophic Sets and Systems, Vol. 35, 2020 410 𝐸 ={π‘Ž ,π‘Ž },𝐸 ={π‘Ž ,π‘Ž },𝐸 ={π‘Ž ,π‘Ž }. 1 11 12 2 21 22 3 31 32 Suppose that 𝐴 ={π‘Ž ,π‘Ž },𝐴 ={π‘Ž ,π‘Ž },𝐴 ={π‘Ž },and 1 11 12 2 21 22 3 31 𝐡 ={π‘Ž },𝐡 ={π‘Ž ,π‘Ž },𝐡 ={π‘Ž ,π‘Ž } 1 11 2 21 22 3 31 32 that is,. 𝐴 ,𝐡 βŠ†πΈ for each 𝑖 =1,2,3. 𝑖 𝑖 𝑖 Let the crisp hypersoft sets (𝐹,𝐀) and (𝐺,𝐁) be defined by (𝐹,𝐀)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ ,π‘₯ }),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ }), 11 21 31 1 2 11 22 31 2 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ ,π‘₯ }),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ ,π‘₯ })}. 12 21 31 3 4 12 22 31 1 4 and (𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ ,π‘₯ }),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ }), 11 21 31 2 3 11 22 31 2 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ ,π‘₯ }),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ ,π‘₯ })}. 11 21 32 1 4 11 22 32 3 4 We have excluded those π›‚βˆˆπ€ for which 𝐹(𝛂) is an empty set (similarly for those π›ƒβˆˆπ for which 𝐺(𝛃) is an empty set). Then the union and intersections of (𝐹,𝐀) and (𝐺,𝐁) are given by: (𝐹,𝐀)βˆͺΜƒ(𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ ,π‘₯ ,π‘₯ }),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ }), 11 21 31 1 2 3 11 22 31 2 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ ,π‘₯ }),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ ,π‘₯ }), 12 21 31 3 4 12 22 31 1 4 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ ,π‘₯ }),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ ,π‘₯ }), 11 21 32 1 4 11 22 32 3 4 ((π‘Ž ,π‘Ž ,π‘Ž ),0 ),((π‘Ž ,π‘Ž ,π‘Ž ),0 )}; 12 21 32 𝐢 12 22 32 𝐢 and (𝐹,𝐀)βˆ©Μƒ(𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ }),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ })}. 11 21 31 2 11 22 31 2 The differences (𝐹,𝐀)\Μƒ(𝐺,𝐁) and (𝐺,𝐁)\Μƒ(𝐹,𝐀) are the following (𝐹,𝐀)\Μƒ(𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ }),((π‘Ž ,π‘Ž ,π‘Ž ),0 )}; 11 21 31 1 11 22 31 𝐢 (𝐺,𝐁)\Μƒ(𝐹,𝐀)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ }),((π‘Ž ,π‘Ž ,π‘Ž ),0 )}. 11 21 31 3 11 22 31 𝐢 Example 2 Let U={x ,x ,x ,x }. Define the attributes sets by: 1 2 3 4 𝐸 ={π‘Ž ,π‘Ž },𝐸 ={π‘Ž ,π‘Ž },𝐸 ={π‘Ž ,π‘Ž }. 1 11 12 2 21 22 3 31 32 Suppose that 𝐴 ={π‘Ž ,π‘Ž },𝐴 ={π‘Ž ,π‘Ž },𝐴 ={π‘Ž },and 1 11 12 2 21 22 3 31 𝐡 ={π‘Ž },𝐡 ={π‘Ž ,π‘Ž },𝐡 ={π‘Ž ,π‘Ž } 1 11 2 21 22 3 31 32 are subsets of 𝐸 for each 𝑖 =1,2,3, that is,. 𝐴 ,𝐡 βŠ†πΈ for each 𝑖. 𝑖 𝑖 𝑖 𝑖 Let the fuzzy hypersoft sets (𝐹,𝐀) and (𝐺,𝐁) be defined by (𝐹,𝐀)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯1,π‘₯2}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯2}), 11 21 31 0.5 0.7 11 22 31 0.3 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯3,π‘₯4}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯1,π‘₯4})}. 12 21 31 0.8 0.9 12 22 31 0.5 0.4 and (𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯2,π‘₯3}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯2}), 11 21 31 0.2 0.9 11 22 31 0.6 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯1,π‘₯4}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯3,π‘₯4})}. 11 21 32 0.4 0.7 11 22 32 0.2 0.8 We have excluded those π›‚βˆˆπ€ for which 𝐹(𝛂) is a null fuzzy set (similarly for those π›ƒβˆˆπ for which 𝐺(𝛃) is a null fuzzy set). Then the union and intersections of (𝐹,𝐀) and (𝐺,𝐁) are given by: Mujahid Abbas, Ghulam Murtaza, and Florentin Smarandache, Basic operations on hypersoft sets and hypersoft point Neutrosophic Sets and Systems, Vol. 35, 2020 411 (𝐹,𝐀)βˆͺΜƒ(𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯1,π‘₯2,π‘₯3}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯2}), 11 21 31 0.5 0.7 0.9 11 22 31 0.6 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯3,π‘₯4}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯1,π‘₯4}), 12 21 31 0.8 0.9 12 22 31 0.5 0.4 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯1,π‘₯4}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯3,π‘₯4}), 11 21 32 0.4 0.7 11 22 32 0.2 0.8 ((π‘Ž ,π‘Ž ,π‘Ž ),0 ),((π‘Ž ,π‘Ž ,π‘Ž ),0 )}; 12 21 32 𝐹 12 22 32 𝐹 and (𝐹,𝐀)βˆ©Μƒ(𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯2}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯2})}. 11 21 31 0.2 11 22 31 0.3 The differences (𝐹,𝐀)\Μƒ(𝐺,𝐁) and (𝐺,𝐁)\Μƒ(𝐹,𝐀) are the following (𝐹,𝐀)\Μƒ(𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯1,π‘₯2}),((π‘Ž ,π‘Ž ,π‘Ž ),0 )}; 11 21 31 0.5 0.5 11 22 31 𝐹 (𝐺,𝐁)\Μƒ(𝐹,𝐀)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯3}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯2})}. 11 21 31 0.9 11 22 31 0.3 Example 3 Let U={x ,x ,x ,x }. Define the attributes sets by: 1 2 3 4 𝐸 ={π‘Ž ,π‘Ž },𝐸 ={π‘Ž ,π‘Ž },𝐸 ={π‘Ž ,π‘Ž }. 1 11 12 2 21 22 3 31 32 Suppose that 𝐴 ={π‘Ž ,π‘Ž },𝐴 ={π‘Ž ,π‘Ž },𝐴 ={π‘Ž },and 1 11 12 2 21 22 3 31 𝐡 ={π‘Ž },𝐡 ={π‘Ž ,π‘Ž },𝐡 ={π‘Ž ,π‘Ž } 1 11 2 21 22 3 31 32 that is,. 𝐴 ,𝐡 βŠ†πΈ for each 𝑖 =1,2,3. 𝑖 𝑖 𝑖 Let the intuitionistic fuzzy hypersoft sets (𝐹,𝐀) and (𝐺,𝐁) be defined by (𝐹,𝐀)={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯2 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 }), 11 21 31 11 22 31 <0.5,0.3> <0.7,0.2> <0.3,0.5> ((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯3 , π‘₯4 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯4 })}. 12 21 31 <0.8,0.1> <0.1,0.5> 12 22 31 <0.5,0.3> <0.4,0.2> and (𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 , π‘₯3 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 }), 11 21 31 <0.2,0.6> <0.8,0.1> 11 22 31 <0.6,0.3> ((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯4 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯3 , π‘₯4 })}. 11 21 32 <0.4,0.5> <0.7,0.2> 11 22 32 <0.4,0.2> <0.1,0.8> We have excluded all those π›‚βˆˆπ€ for which 𝐹(𝛂) is a null intuitionistic fuzzy set (similarly for those π›ƒβˆˆπ for which 𝐺(𝛃) is a null intuitionistic fuzzy set). The union and intersections of (𝐹,𝐀) and (𝐺,𝐁) are given by: (𝐹,𝐀)βˆͺΜƒ(𝐺,𝐁) ={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯2 , π‘₯3 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 }), 11 21 31 <0.5,0.3> <0.7,0.2> <0.8,0.1> 11 22 31 <0.6,0.3> ((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯3 , π‘₯4 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯4 }), 12 21 31 <0.8,0.1> <0.1,0.5> 12 22 31 <0.5,0.3> <0.4,0.2> ((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯4 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯3 , π‘₯4 }), 11 21 32 <0.4,0.5> <0.7,0.2> 11 22 32 <0.4,0.2> <0.1,0.8> ((π‘Ž ,π‘Ž ,π‘Ž ),0 ),((π‘Ž ,π‘Ž ,π‘Ž ),0 )}; 12 21 32 𝐼𝐹 12 22 32 𝐼𝐹 and (𝐹,𝐀)βˆ©Μƒ(𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 })}. 11 21 31 <0.2,0.6> 11 22 31 <0.3,0.5> Mujahid Abbas, Ghulam Murtaza, and Florentin Smarandache, Basic operations on hypersoft sets and hypersoft point Neutrosophic Sets and Systems, Vol. 35, 2020 412 The differences (𝐹,𝐀)\Μƒ(𝐺,𝐁) and (𝐺,𝐁)\Μƒ(𝐹,𝐀) are the following (𝐹,𝐀)\Μƒ(𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯2 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 })}; 11 21 31 <0.5,0.3> <0.6,0.2> 11 22 31 <0.3,0.6> (𝐺,𝐁)\Μƒ(𝐹,𝐀)={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 , π‘₯3 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 })}. 11 21 31 <0.2,0.7> <0.8,0.1> 11 22 31 <0.5,0.3> Example 4 Let U={x ,x ,x ,x }. Define the attributes sets by: 1 2 3 4 𝐸 ={π‘Ž ,π‘Ž },𝐸 ={π‘Ž ,π‘Ž },𝐸 ={π‘Ž ,π‘Ž }. 1 11 12 2 21 22 3 31 32 Suppose that 𝐴 ={π‘Ž ,π‘Ž },𝐴 ={π‘Ž ,π‘Ž },𝐴 ={π‘Ž },and 1 11 12 2 21 22 3 31 𝐡 ={π‘Ž },𝐡 ={π‘Ž ,π‘Ž },𝐡 ={π‘Ž ,π‘Ž } 1 11 2 21 22 3 31 32 that is,. 𝐴 ,𝐡 βŠ†πΈ for each 𝑖 =1,2,3. 𝑖 𝑖 𝑖 Let the neutrosophic hypersoft sets (𝐹,𝐀) and (𝐺,𝐁) be defined by (𝐹,𝐀)={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯2 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 }), 11 21 31 <0.5,0.2,0.3> <0.7,0.3,0.2> 11 22 31 <0.3,0.2,0.5> ((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯3 , π‘₯4 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯4 })}. 12 21 31 <0.8,0.4,0.1> <0.1,0.5,0.5> 12 22 31 <0.5,0.2,0.3> <0.4,0.3,0.2> and (𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 , π‘₯3 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 }), 11 21 31 <0.2,0.5,0.6> <0.8,0.6,0.1> 11 22 31 <0.6,0.2,0.3> ((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯4 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯3 , π‘₯4 })}. 11 21 32 <0.4,0.3,0.5> <0.7,0.3,0.2> 11 22 32 <0.4,0.4,0.2> <0.1,0.3,0.8> We have excluded those π›‚βˆˆπ€ for which 𝐹(𝛂) is a null intuitionistic fuzzy set (similarly for those π›ƒβˆˆπ for which 𝐺(𝛃) is a null intuitionistic fuzzy set). The union and intersections of (𝐹,𝐀) and (𝐺,𝐁) are given by: (𝐹,𝐀)βˆͺΜƒ(𝐺,𝐁) ={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯2 , π‘₯3 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 }), 11 21 31 <0.5,0.2,0.3> <0.7,0.3,0.2> <0.8,0.6,0.1> 11 22 31 <0.6,0.2,0.3> ((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯3 , π‘₯4 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯4 }), 12 21 31 <0.8,0.4,0.1> <0.1,0.5,0.5> 12 22 31 <0.5,0.2,0.3> <0.4,0.3,0.2> ((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯4 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯3 , π‘₯4 }), 11 21 32 <0.4,0.3,0.5> <0.7,0.3,0.2> 11 22 32 <0.4,0.4,0.2> <0.1,0.3,0.8> ((π‘Ž ,π‘Ž ,π‘Ž ),0 ),((π‘Ž ,π‘Ž ,π‘Ž ),0 )}; 12 21 32 𝑁 12 22 32 𝑁 and (𝐹,𝐀)βˆ©Μƒ(𝐺,𝐁) ={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 })}. 11 21 31 <0.2,0.5,0.6> 11 22 31 <0.3,0.2,0.5> The differences (𝐹,𝐀)\Μƒ(𝐺,𝐁) and (𝐺,𝐁)\Μƒ(𝐹,𝐀) are the following (𝐹,𝐀)\Μƒ(𝐺,𝐁) Mujahid Abbas, Ghulam Murtaza, and Florentin Smarandache, Basic operations on hypersoft sets and hypersoft point Neutrosophic Sets and Systems, Vol. 35, 2020 413 ={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯1 , π‘₯2 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 })}; 11 21 31 <0.5,0.2,0.3> <0.6,0.15,0.2> 11 22 31 <0.3,0.4,0.6> (𝐺,𝐁)\Μƒ(𝐹,𝐀) ={((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 , π‘₯3 }),((π‘Ž ,π‘Ž ,π‘Ž ),{ π‘₯2 })}. 11 21 31 <0.2,0.15,0.7> <0.8,0.6,0.1> 11 22 31 <0.5,0.4,0.3> Remark 3 There are four types of plithogenic hypersoft sets namely: plithogenic crisp hypersoft set, plithogenic fuzzy hypersoft set, plithogenic intuitionistic fuzzy hypersoft set, plithogenic neutrosophic hypersoft set. Here we discuss only plithogenic crisp hypersoft point whereas examples for other types of sets can be constructed in the similar way. Example 5 Let U={x ,x ,x ,x }. Define the attributes sets by: 1 2 3 4 𝐸 ={π‘Ž ,π‘Ž },𝐸 ={π‘Ž ,π‘Ž },𝐸 ={π‘Ž ,π‘Ž }. 1 11 12 2 21 22 3 31 32 Suppose that 𝐴 ={π‘Ž ,π‘Ž },𝐴 ={π‘Ž ,π‘Ž },𝐴 ={π‘Ž },and 1 11 12 2 21 22 3 31 𝐡 ={π‘Ž },𝐡 ={π‘Ž ,π‘Ž },𝐡 ={π‘Ž ,π‘Ž } 1 11 2 21 22 3 31 32 that is,. 𝐴 ,𝐡 βŠ†πΈ for each 𝑖 =1,2,3. 𝑖 𝑖 𝑖 Let the plithogenic crisp hypersoft sets (𝐹,𝐀) and (𝐺,𝐁) be defined by (𝐹,𝐀)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,0,1),π‘₯ (1,1,1)}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (0,0,1)}), 11 21 31 1 2 11 22 31 2 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,1,0),π‘₯ (1,1,1)}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,0,1),π‘₯ (0,1,0)})}. 12 21 31 3 4 12 22 31 1 4 and (𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,1,1),π‘₯ (1,1,0)}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (0,1,0)}), 11 21 31 2 3 11 22 31 2 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (0,1,1),π‘₯ (1,1,1)}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,1,1),π‘₯ (1,1,1)})}. 11 21 32 1 4 11 22 32 3 4 We have excluded all those π›‚βˆˆπ€ for which 𝐹(𝛂) is a null plithogenic crisp set (similarly for those π›ƒβˆˆπ for which 𝐺(𝛃) is a null plithogenic crisp set). The union and intersections of (𝐹,𝐀) and (𝐺,𝐁) are given by: (𝐹,𝐀)βˆͺΜƒ(𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,0,1),π‘₯ (1,1,1),π‘₯ (1,1,0)}), 11 21 31 1 2 3 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (0,1,1)}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,1,0),π‘₯ (1,1,1)}), 11 22 31 2 12 21 31 3 4 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,0,1),π‘₯ (0,1,0)}), 12 22 31 1 4 ((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (0,1,1),π‘₯ (1,1,1)}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,1,1),π‘₯ (1,1,1)}), 11 21 32 1 4 11 22 32 3 4 ((π‘Ž ,π‘Ž ,π‘Ž ),0 ),((π‘Ž ,π‘Ž ,π‘Ž ),0 )}; 12 21 32 𝑃𝐢 12 22 32 𝑃𝐢 and (𝐹,𝐀)βˆ©Μƒ(𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,1,1)}),((π‘Ž ,π‘Ž ,π‘Ž ),0 )}. 11 21 31 2 11 22 31 𝑃𝐢 The differences (𝐹,𝐀)\Μƒ(𝐺,𝐁) and (𝐺,𝐁)\Μƒ(𝐹,𝐀) are the following (𝐹,𝐀)\Μƒ(𝐺,𝐁)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,0,1)}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (0,0,1)})}; 11 21 31 1 11 22 31 2 (𝐺,𝐁)\Μƒ(𝐹,𝐀)={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (1,1,0)}),((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ (0,1,0)})}. 11 21 31 3 11 22 31 2 Proposition 1 Let (𝐹,𝑨) be a *-hypersoft set over π‘ˆ . Then the following holds; βˆ— 1. (𝐹,𝐀)βˆͺΜƒΞ¦ =(𝐹,𝐀); 𝐀 Mujahid Abbas, Ghulam Murtaza, and Florentin Smarandache, Basic operations on hypersoft sets and hypersoft point Neutrosophic Sets and Systems, Vol. 35, 2020 414 2. (𝐹,𝐀)βˆ©ΜƒΞ¦ =Ξ¦ ; 𝐀 𝐀 3. (𝐹,𝐀)βˆͺΜƒπ‘ˆΜƒ =π‘ˆΜƒ ; 𝐀 𝐀 4. (𝐹,𝐀)βˆ©Μƒπ‘ˆΜƒ =(𝐹,𝐀); 𝐀 5. π‘ˆΜƒ \Μƒ(𝐹,𝐀)=(𝐹,𝐀)𝑐; 𝐀 6. (𝐹,𝐀)βˆͺΜƒ(𝐹,𝐀)𝑐 =π‘ˆΜƒ ; 𝐀 7. (𝐹,𝐀)βˆ©Μƒ(𝐹,𝐀)𝑐 =Ξ¦ . 𝐀 Proof. We will prove only (i), (ii) and (v) and proofs of remaining are similar. (i) By the definition of union, we have (𝐹,𝐀)βˆͺΜƒΞ¦ =(𝐻,𝐂), 𝐀 where 𝐂=𝐀 and 𝐻(𝛂)=𝐹(𝛂)βˆͺ 0 =𝐹(𝛂) for all π›‚βˆˆπ‚. Hence (𝐻,𝐂)=(𝐹,𝐀). βˆ— βˆ— (ii) By the definition of intersection, we obtain that (𝐹,𝐀)βˆ©ΜƒΞ¦ =(𝐻,𝐂), 𝐀 where 𝐂=𝐀 and 𝐻(𝛂)=𝐹(𝛂)∩ 0 =0 for all π›‚βˆˆπ‚. Hence (𝐻,𝐂)=Ξ¦ . βˆ— βˆ— βˆ— 𝐀 (v) By the definition of difference, we get π‘ˆΜƒ \Μƒ(𝐹,𝐀)=(𝐻,𝐂), 𝐀 where 𝐂=𝐀 and 𝐻(𝛂)=π‘ˆ\ 𝐹(𝛂)=𝐹𝑐(𝛂) for all π›‚βˆˆπ‚. Hence (𝐻,𝐂)=(𝐹,𝐀)𝑐. βˆ— 3. Hypersoft point In this section, we define hypersoft point in different frameworks and study some basic properties of such points in each setup. 3.1 Crisp hypersoft point Definition 9 Let π‘¨βŠ†π‘¬, πœΆβˆˆπ‘¨, and π‘₯ βˆˆπ‘ˆ. A hypersoft set (𝐹,𝑨) is said to be a hypersoft point if 𝐹(πœΆβ€²) is an empty set for every πœΆβ€² βˆˆπ‘¨\{𝜢} and 𝐹(𝜢) is a singleton set. We will denote hypersoft point (𝐹,𝑨) simply by 𝑃(𝜢,π‘₯). Definition 10 A hypersoft set (𝐹,𝑨) is said to be an empty hypersoft point if 𝐹(𝜢) is an empty set for each πœΆβˆˆπ‘¨. We will denote an empty hypersoft set, corresponding to 𝜢, by 𝑃(𝜢,βŒ€). As a matter of fact if (𝐹,𝐀) is a null hypersoft set then for every π›‚βˆˆπ€ it may be regarded as empty hypersoft set 𝑃(𝛂,βŒ€). Definition 11 A hypersoft point 𝑃(𝜢,π‘₯) is said to belong to a hypersoft set (𝐺,𝑨) if 𝑃(𝜢,π‘₯) βŠ†Μƒ (𝐺,𝑨). We write it as 𝑃(𝜢,π‘₯) βˆˆΜƒ (𝐺,𝑨). It is straightforward to check that the hypersoft union of hypersoft points of a hypersoft set (𝐺,𝐀) returns the hypersoft set (𝐺,𝐀), that is, (𝐺,𝐀)=βˆͺΜƒ{𝑃(𝛂,π‘₯):𝑃(𝛂,π‘₯) βˆˆΜƒ (𝐺,𝐀)}. We illustrate the above observation through the following example. Mujahid Abbas, Ghulam Murtaza, and Florentin Smarandache, Basic operations on hypersoft sets and hypersoft point Neutrosophic Sets and Systems, Vol. 35, 2020 415 Example 6 Let U={x ,x ,x ,x }, and (F,𝐀) be as given in the example 1. Then the hypersoft points 1 2 3 4 of (F,𝐀) are the following: 𝑃((π‘Ž11,π‘Ž21,π‘Ž31),π‘₯1) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ })}; 1 11 21 31 1 𝑃((π‘Ž11,π‘Ž21,π‘Ž31),π‘₯2) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ })}; 2 11 21 31 2 𝑃((π‘Ž11,π‘Ž22,π‘Ž31),π‘₯2) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ })}; 3 11 22 31 2 𝑃((π‘Ž12,π‘Ž21,π‘Ž31),π‘₯3) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ })}; 4 12 21 31 3 𝑃((π‘Ž12,π‘Ž21,π‘Ž31),π‘₯4) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ })}; 5 12 21 31 4 𝑃((π‘Ž12,π‘Ž22,π‘Ž31),π‘₯1) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ })}; 6 12 22 31 1 𝑃((π‘Ž12,π‘Ž22,π‘Ž31),π‘₯4) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯ })}. 7 12 22 31 4 Moreover (𝐹,𝐀)=𝑃((π‘Ž11,π‘Ž21,π‘Ž31),π‘₯1)βˆͺ̃𝑃((π‘Ž11,π‘Ž21,π‘Ž31),π‘₯2)βˆͺ̃𝑃((π‘Ž11,π‘Ž22,π‘Ž31),π‘₯2) 1 2 3 βˆͺ̃𝑃((π‘Ž12,π‘Ž21,π‘Ž31),π‘₯3)βˆͺ̃𝑃((π‘Ž12,π‘Ž21,π‘Ž31),π‘₯4)βˆͺ̃𝑃((π‘Ž12,π‘Ž22,π‘Ž31),π‘₯1)βˆͺ̃𝑃((π‘Ž12,π‘Ž22,π‘Ž31),π‘₯4). 4 5 6 7 Proposition 2 Let (𝐹,𝑨),(𝐹 ,𝑨) and (𝐹 ,𝑨) be hypersoft sets over π‘ˆ. Then the following hold: 1 2 1. If (𝐹,𝑨) is not a null hypersoft set, then (𝐹,𝑨) contains at least one nonempty hypersoft point. 2. (𝐹 ,𝑨)βŠ†Μƒ (𝐹 ,𝑨) if and only if 𝑃(𝜢,π‘₯) βˆˆΜƒ(𝐹 ,𝑨) implies that 𝑃(𝜢,π‘₯) βˆˆΜƒ(𝐹 ,𝑨). 1 2 1 2 3. 𝑃(𝜢,π‘₯) βˆˆΜƒ(𝐹 ,𝑨)βˆͺΜƒ(𝐹 ,𝑨) if and only if 𝑃(𝜢,π‘₯) βˆˆΜƒ(𝐹 ,𝑨) or 𝑃(𝜢,π‘₯) βˆˆΜƒ(𝐹 ,𝑨). 1 2 1 2 4. 𝑃(𝜢,π‘₯) βˆˆΜƒ(𝐹 ,𝑨)βˆ©Μƒ(𝐹 ,𝑨) if and only if 𝑃(𝜢,π‘₯) βˆˆΜƒ(𝐹 ,𝑨) and 𝑃(𝜢,π‘₯) βˆˆΜƒ(𝐹 ,𝑨). 1 2 1 2 5. 𝑃(𝜢,π‘₯) βˆˆΜƒ(𝐹 ,𝑨)\Μƒ(𝐹 ,𝑨) if and only if 𝑃(𝜢,π‘₯) βˆˆΜƒ(𝐹 ,𝑨) and 𝑃(𝜢,π‘₯) βˆ‰Μƒ (𝐹 ,𝑨). 1 2 1 2 Proof. We will prove (1), (2) and (3). Proofs of (4) and (5) are similar to that of (3). (1) Suppose that (𝐹,𝐀) is not a null hypersoft set, that is, 𝐹(𝛂)β‰ βŒ€ for some π›‚βˆˆπ€. Now if 𝛂 βˆˆπ€ 0 is such that 𝐹(𝛂 )β‰ βŒ€, then for π‘₯ ∈𝐹(𝛂 ), there will be a hypersoft point 𝑃(𝛂0,π‘₯) such that 0 0 𝑃(𝛂0,π‘₯) βˆˆΜƒ(𝐹,𝐀). (2) Suppose that (𝐹 ,𝐀)βŠ†Μƒ (𝐹 ,𝐀) and 𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀). By the definition 11, we have 1 2 1 𝑃(𝛂,π‘₯) βŠ†Μƒ (𝐹 ,𝐀). 1 Thus 𝑃(𝛂,π‘₯) βŠ†Μƒ (𝐹 ,𝐀)βŠ†Μƒ (𝐹 ,𝐀) 1 2 implies that 𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀). 2 Conversely suppose that 𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀) which implies that 𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀). By the 1 2 definition 11, we obtain that 𝑃(𝛂,π‘₯) βŠ†Μƒ (𝐹 ,𝐀)forall𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀). 2 1 Thus we have (𝐹 ,𝐀)=βˆͺΜƒ{𝑃(𝛂,π‘₯):𝑃(𝛂,π‘₯) βˆˆΜƒ (𝐺,𝐀)}βŠ†Μƒ (𝐹 ,𝐀). 1 2 (3) Suppose that 𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀)βˆͺΜƒ(𝐹 ,𝐀). It follows from the definition 11 that 1 2 𝑃(𝛂,π‘₯) βŠ†Μƒ (𝐹 ,𝐀)βˆͺΜƒ(𝐹 ,𝐀), 1 2 which implies that π‘₯ ∈𝐹 (𝛂)βˆͺ 𝐹 (𝛂). Thus π‘₯ ∈𝐹 (𝛂) or 𝐹 (𝛂). Hence we have 1 𝐢 2 1 2 𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀)or𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀). 1 2 Conversely suppose that 𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀) or 𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀). This implies that π‘₯ ∈𝐹 (𝛂) or 𝐹 (𝛂). 1 2 1 2 Thus π‘₯ ∈𝐹 (𝛂)βˆͺ 𝐹 (𝛂) and so we have 1 𝐢 2 𝑃(𝛂,π‘₯) βŠ†Μƒ (𝐹 ,𝐀)βˆͺΜƒ(𝐹 ,𝐀). 1 2 Mujahid Abbas, Ghulam Murtaza, and Florentin Smarandache, Basic operations on hypersoft sets and hypersoft point Neutrosophic Sets and Systems, Vol. 35, 2020 416 3.2 Fuzzy hypersoft point Definition 12 Let π‘¨βŠ†π‘¬, πœΆβˆˆπ‘¨, and π‘₯ βˆˆπ‘ˆ . A fuzzy hypersoft set (𝐹,𝑨) is said to be a fuzzy hypersoft 𝐹 point if 𝐹(πœΆβ€²) is a null fuzzy set for every πœΆβ€² βˆˆπ‘¨\{𝜢} and 𝐹(𝜢)(𝑦)=0 for all 𝑦≠π‘₯. We will denote (𝐹,𝑨) simply by 𝐹𝑃(𝜢,π‘₯). Definition 13 A fuzzy hypersoft set (𝐹,𝑨) is said to be a null fuzzy hypersoft point if 𝐹(𝜢) is a null fuzzy set for each πœΆβˆˆπ‘¨. We denote a null fuzzy hypersoft set, corresponding to 𝜢, by 𝐹𝑃(𝜢,0𝐹). Note that if (𝐹,𝐀) is a null fuzzy hypersoft set then for every π›‚βˆˆπ€, it can be regarded as null fuzzy hypersoft set 𝐹𝑃(𝛂,0𝐹). Definition 14 A fuzzy hypersoft point 𝐹𝑃(𝜢,π‘₯) is said to belong to a fuzzy hypersoft set (𝐺,𝑨) if 𝐹𝑃(𝜢,π‘₯) βŠ†Μƒ (𝐺,𝑨). We write it as 𝐹𝑃(𝜢,π‘₯) βˆˆΜƒ(𝐺,𝑨). It is straightforward to check that the fuzzy hypersoft union of fuzzy hypersoft points of a fuzzy hypersoft set (𝐺,𝐀) returns the fuzzy hypersoft set (𝐺,𝐀), that is, (𝐺,𝐀)=βˆͺΜƒ{𝐹𝑃(𝛂,π‘₯):𝐹𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐺,𝐀)}. We illustrate this observation through the following example. Example 7 Let U={x ,x ,x ,x }, and (F,𝐀) be as given in the example 2. Then some of the fuzzy 1 2 3 4 hypersoft points of (F,𝐀) are given as: 𝐹𝑃((π‘Ž11,π‘Ž21,π‘Ž31),π‘₯1) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯1})}; 1 11 21 31 0.5 𝐹𝑃((π‘Ž11,π‘Ž21,π‘Ž31),π‘₯1) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯1})}; 2 11 21 31 0.2 𝐹𝑃((π‘Ž11,π‘Ž21,π‘Ž31),π‘₯2) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯2})}; 3 11 21 31 0.7 𝐹𝑃((π‘Ž11,π‘Ž22,π‘Ž31),π‘₯2) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯2})}; 4 11 22 31 0.3 𝐹𝑃((π‘Ž12,π‘Ž21,π‘Ž31),π‘₯3) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯3})}; 5 12 21 31 0.8 𝐹𝑃((π‘Ž12,π‘Ž21,π‘Ž31),π‘₯4) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯4})}; 6 12 21 31 0.6 𝐹𝑃((π‘Ž12,π‘Ž21,π‘Ž31),π‘₯4) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯4})}; 7 12 21 31 0.9 𝐹𝑃((π‘Ž12,π‘Ž22,π‘Ž31),π‘₯1) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯1})}; 8 12 22 31 0.5 𝐹𝑃((π‘Ž12,π‘Ž22,π‘Ž31),π‘₯4) ={((π‘Ž ,π‘Ž ,π‘Ž ),{π‘₯4})}. 9 12 22 31 0.4 Moreover we have (𝐹,𝐀)=𝐹𝑃((π‘Ž11,π‘Ž21,π‘Ž31),π‘₯1)βˆͺ̃𝐹𝑃((π‘Ž11,π‘Ž21,π‘Ž31),π‘₯1)βˆͺ̃𝐹𝑃((π‘Ž11,π‘Ž21,π‘Ž31),π‘₯2) 1 2 3 βˆͺ̃𝐹𝑃((π‘Ž11,π‘Ž22,π‘Ž31),π‘₯2)βˆͺ̃𝐹𝑃((π‘Ž12,π‘Ž21,π‘Ž31),π‘₯3)βˆͺ̃𝐹𝑃((π‘Ž12,π‘Ž21,π‘Ž31),π‘₯4) 4 5 6 βˆͺ̃𝐹𝑃((π‘Ž12,π‘Ž21,π‘Ž31),π‘₯4)βˆͺ̃𝐹𝑃((π‘Ž12,π‘Ž22,π‘Ž31),π‘₯1)βˆͺ̃𝐹𝑃((π‘Ž12,π‘Ž22,π‘Ž31),π‘₯4). 7 8 9 Proposition 3 Let (𝐹,𝑨),(𝐹 ,𝑨) and (𝐹 ,𝑨) be fuzzy hypersoft sets over π‘ˆ. Then the following hold: 1 2 1. If (𝐹,𝐀) is not a null fuzzy hypersoft set, then (𝐹,𝐀) contains at least one nonnull fuzzy hypersoft point. 2. (𝐹 ,𝐀)βŠ†Μƒ (𝐹 ,𝐀) if and only if 𝐹𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀) implies that 𝐹𝑃(𝛂,π‘₯) βˆˆΜƒ(𝐹 ,𝐀). 1 2 1 2 Mujahid Abbas, Ghulam Murtaza, and Florentin Smarandache, Basic operations on hypersoft sets and hypersoft point

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