American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) ISSN (Print) 2313-4410, ISSN (Online) 2313-4402 © Global Society of Scientific Research and Researchers http://asrjetsjournal.org/ Soft Pre-Open Sets In Soft Bitopological Spaces Ameer Mohammed Hussein Hasan* Department of mathematics Faculty of mathematics and computer science university of kufa, Najaf, Iraq Email: [email protected] Abstract In this work , I introduce the concept of soft bitopological space on a soft set and some definitions on soft preopen set on soft bitopological space . Also introduce soft pre separation axioms , Spre- T , Spre- T1 and Spre- T2 , with study some properties in soft bitopological space. Keywords: Soft set; Soft pre-open; Soft topology; Soft bitopological spaces. 1. Introduction Many classical methods have been used to solve some complicated problems in engineering economics and environment. For instance, the interval mathematics, theory of fuzzy, theory of probability, and sets which can consider as mathematical tools for dealing with uncertainties since all these theories have their own problems and difficulties. In [2], the author in 1999 introduced the notion of soft set, which is free of difficulties in solving aforementioned problems, and it has been applied over many different fields. In 2011, Naim Cagman and his colleagues introduced a new concept of soft set called soft topology define by using the soft power set of soft set , and this first idea to soft mathematical concepts and structures that are based on the operations of theoretic soft set [6]. In 2011[7], the authors defined the concept of"soft topology on the collection of soft sets over"with some basic notations of soft topological spaces. In [6], the notion of soft topology was more general than that in [7]. Therefore, algebraists continue investigating the work of Cagman [6]"and follow their notations and mathematical formalism. In 2013 J. Subhashini and C. Sekar defined soft pre-open sets [4]"by following Cagman’s theory of soft topology. Therefore, this paper has introduced soft bitopological space relying on [6] and defined the soft pre-open set of soft bitopological space. Also, I have discussed soft pre separation axioms , Spre- T , Spre- T1 and Spre- T2 . -----------------------------------------------------------------------* Corresponding author. 42 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2016) Volume 26, No 4 , pp 42-53 2. Preliminaries Through this section , I give and introduction some important definitions and facts about soft topology and recall primary definition soft set that need in this work . 2.1. Definition [2] The set of ordered pairs U , where represents a soft set is mapping and the set of all soft sets over FA on the universe f A is called an approximate function of the soft set FA . However , U is denoted by S S (U ) . 2.2. Definition [5] Let FA ∈ S S (U ) . If Moreover , If x ∈ A , then FA is called an empty set and denoted by Fφ . for all f A = U for all x ∈ A , then FA is called an A -universal soft set and denoted by FAˆ . But , If A = E , then A -universal soft set is called universal soft set and denoted by FE~ . 2.3. Definition [5] Let FA , FB ∈ S S (U ) . If f A ( x ) ⊆ f B ( x ) for all x , then , FA is a soft subset of FB and denoted by . 2.4. Definition [5] Let ~ F , however , the soft intersection is denoted FA , FB ∈ S S (U ) . Then, the soft union is denoted by FA ∪ B by ~ ~ F Also , the soft difference of F and F is denoted by F ∆ FA ∩ A FB , are defined by the approximate B A B functions , , respectively, on the onther hand , the soft complement , ~ FAc of FA is defined by the approximate function f c ( x ) = f Ac ( x ) , where f Ac (x ) is the complement of the set f A (x ) ; that is, f Ac ( x ) = U − f A ( x ) for all A ~ ~ ~ x ∈ A . It is easy to see that ( FAc ) c = FA and Fφc = FE~ . 2.5. Proposition [5] Let 1- FA , FB , FC ∈ S S (U ) . Then , . 43 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2016) Volume 26, No 4 , pp 42-53 2- . 3- . 4- . 5- . 6- . 7- . ~ 8- FA ∪ ( FB ~ F ) = (F ∪ ~ F )∩ ~ (F ∪ ~ F )&F ∩ ~ (F ∪ ~ F ) = (F ∩ ~ F )∪ ~ (F ∩ ~ F ). ∩ C A B A C A B C A B A C 2.6. Definition [6] Let FA ∈ S S (U ) ."The soft power set of FA is defined by". cardinality is defined by , where and its | f A ( x ) | is the cardinality of f A (x ) . 2.7. Definition [6] Let FA ∈ S S (U ) . A soft topology on FA , denoted by τ~ , is a collection of soft subsets of FA having the following properties: • Fφ , FA ∈τ~ . • . • . 2.8. Definition [6] Let ( FA ,τ~ ) be a soft space on FA . Every element of τ~ is called a soft open sets . 2.9. Definition [6] Let ( FA ,τ~ ) be a soft space on FA and 44 ~F FB ⊆ A . Then , the collection American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2016) Volume 26, No 4 , pp 42-53 ~ F : F ∈τ~, i ∈ I ⊆ N } τ~FB = {FAi ∩ B Ai called a soft topological subspace of is called a soft subspace topology on FB . Hence, ( FB ,τ~F ) is B ( FA ,τ~ ) . 2.10. Definition [6] Let ~ F . The soft interior of F , denoted F , is defined as the ( FA ,τ~ ) be a soft space on FA and FB ⊆ A B B union of all soft open subsets of FB . Note that FB is the biggest soft open set that is contained by FB . 2.11. Theorem [6] Let ~ F . Then , ( FA ,τ~ ) be a soft space on FA and FB , FC ⊆ A 1- ( FB ) 2- FB = FB ~ F ~ F . Then , F ⊆ ⊆ B C C 3- FB ~ F = (F ∩ ~ F ) ∩ C B C ~ F ⊆ ~ F ) ~ (F ∪ ∪ C B C 4- FB 2.12. Definition [6] Let ~ F . Then, the soft closure of F , denoted F B is defined as the ( FA ,τ~ ) be a soft space on FA and FB ⊆ A B soft intersection of all soft closed superset of FB . Note that F B is the smallest soft closed set that containing FB . 2.13. Theorem [6] Let ~ F . Then , ( FA ,τ~ ) be a soft space on FA and FB , FC ⊆ A 1- ( F B ) = 2- ( F B ) 3- FB c~ FB . ~ = ( FBc ) . ~ F . Then , ⊆ C . 45 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2016) Volume 26, No 4 , pp 42-53 4- . 5- . 2.14. Theorem [6] Let ~F . ~F ⊆ ~ F Then F ⊆ ( FA ,τ~ ) be a soft space on FA and FB ⊆ B B B A 2.15. Definition Let ( FA ,τ~1 ) and ( FA ,τ~2 ) be the two different soft topologies on FA . Then ( FA ,τ~1 ,τ~2 ) is called a soft bitopological space . 2.16. Example Let U = {u1 , u2 , u3 , u4 } , E = {w1 , w2 , w3} , then FA = {( w1 , {u1})} 1 FA = {( w1 , {u2 })} 2 FA = {( w2 , {u3})} 4 FA = {( w2 , {u4 })} 5 FA = {( w2 , {u3 , u4 })} 6 FA = {( w1 , {u1}), ( w2 , {u3})} 7 FA = {( w1 , {u1}), ( w2 , {u4 })} 8 FA = {( w1 , {u2 }), (( w2 , {u3})} 10 46 A = {w1 , w2 } such that ~E A⊆ and American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2016) Volume 26, No 4 , pp 42-53 FA = {( w1 , {u2 }), ( w2 , {u4 })} 11 FA = {( w1 , {u2 }), ( w2 , {u3 , u4 })} 12 FA = {( w1 , {u1 , u2 }), ( w2 , {u4 })} 14 FA = FA 15 FA = Fφ 16 Then τ~1 = {Fφ , FA} and τ~2 = {Fφ , FA , FA2 , FA11 } are a soft topology of FA then ( FA ,τ~1 ,τ~2 ) , is a soft bitopological space . 2.17. Definition ~F . Then ( FA ,τ~1 ,τ~2 ) be a soft bitopological space over FA and FB ⊆ A ~ F : F ∈τ~ , i ∈ I ⊆ N } are said to be the ~ F : F ∈τ~ , i ∈ I ⊆ N } and τ~ F = {F ∩ τ~1FB = {FA ∩ 2 B A B A 2 1 B A Let i i i relative topologies on i FB . Then ( FB ,τ~1FB ,τ~2 FB ) is called a relative soft bitopological space of ( FA ,τ~1 ,τ~2 ) 2.18. Theorem If ~ τ~ is a soft topological space over F . ( FA ,τ~1 ,τ~2 ) is a soft bitopological space then τ~1 ∩ 2 A Proof :- ~ • Fφ , FA ∈τ~1 ∩ τ~2 . • Let ~ τ~ ⇒ F ∈τ~ and F ∈τ~ for all i ∈ I . Therefore {FA , i ∈ I } be a family of soft sets in τ~1 ∩ 2 1 A 2 A FA ∈τ~1 and i∈I i i i i∈I FA ∈τ~2 . Thus i • Let 1 n′ i =1 i∈I ~ τ~ . FA ∈τ~1 ∩ 2 i FA ∈τ~1 and . Then FA ∈τ~1 and i 1 n′ i =1 FA ∈τ~2 . Therefore i i 1 n′ i =1 i ~ τ~ ,1 ≤ i ≤ n′, n′ ∈ N . FA ∈τ~1 ∩ 2 i 47 . Since American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2016) Volume 26, No 4 , pp 42-53 2.19. Remark If ~ τ~ is not a soft topological space over F . ( FA ,τ~1 ,τ~2 ) is a soft bitopological space then τ~1 ∪ 2 A 2.20. Example Let us consider 2.16 and let τ~1 = {Fφ , FA , FA1 } and τ~2 = {Fφ , FA , FA2 } are soft topology of FA then ~ τ~ = {F , F , F , F } . If take F , F ( FA ,τ~1 ,τ~2 ) is soft bitopological space . Now τ~1 ∪ φ A A A 2 A A 1 2 1 2 , ~ τ~ is not soft topology on F . ~ F = {( x , {u }), ( x , {u })} ∉τ~ ∪ ~ τ~ . Thus τ~ ∪ FA ∪ A 1 1 1 2 1 2 1 2 A 1 2 3. Some Definition of Soft Pre-open set in soft bitopological space In this section introduce some definitions of soft pre-open set , soft pre-closed , soft pre-neighborhood , soft preclosure and soft pre-interior on soft bitopological space . 3.1. Definition Let ~ F , F is called soft pre-open set with respect to ( FA ,τ~1 ,τ~2 ) be soft bitopological space and let FB ⊆ A B the two soft topological spaces τ~1 and τ~2 if ~ ( F B ) . FB ⊆ 3.2. Notes 1- The set of all soft pre-open set with respect to the two soft topologies is denoted by Pre( FA ). 2- The relative soft bitopological space for FB with respect to Soft pre-open sets is the collection Pre ~ F : F ∈ Pre( F )} ( FA ) F given by Pre ( FA ) F = {FC ∩ B C A B B 3- Any τ~2 -open soft set is not necessarily to be soft pre-open set . 4- Any soft pre-open set is not necessarily to be of τ~1 -open ( τ~2 -open ) soft set . 3.3. Example Let us consider example 2.20 , ~ F then ( FA ,τ~1 ,τ~2 ) is soft bitopological space . Take FA ⊆ A 1 ~ ( F A )A ⇒ F is soft per-open set with respect to the two soft topological spaces τ~ and τ~ . FA ⊆ A 1 2 1 1 1 3.4. Remarks 1- The intersection of any soft pre-open sets is not necessary a soft pre-open set 48 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2016) Volume 26, No 4 , pp 42-53 2- The union of any soft pre-open sets is soft pre-open set with respect to soft bitopological space . The example to part (1) is simply . The following proof explain the part (2) of the remark 3.4 . Let FB and ~ ( F B ) and FC be a two soft pre-open sets with respect to soft bitopological space ( FA ,τ~1 ,τ~2 ) . i.e. FB ⊆ ~ ( F C ) FC ⊆ with respect to the two ~F ⊆ ~ ( F C ) ⊆ ~ F C ) ~ ( F B ) ∪ ~ (F B ∪ τ~2 ⇒ FB ∪ C . soft topological spaces τ~1 Since and then ~F ⊆ ~ F ) with respect to the two soft topological spaces τ~ and τ~ . ~ (F ∪ FB ∪ C B C 1 2 3.5. Definition Let ~ F , F is called soft pre-closed set of F if and ( FA ,τ~1 ,τ~2 ) is soft bitopological space and let FB ⊆ A B A only if ~ FBc is soft pre-open set of FA . 3.6. Definition Let ~ F is said to be soft pre-neighborhood of a ( FA ,τ~1 ,τ~2 ) is soft bitopological space and α ∈ FA , FB ⊆ A point α if there is a soft pre-open set point α is denoted by Spre- υ~ (α ) . ~ F . The set of all soft pre-neighborhoods of a FC such that α ∈ FC ⊆ B 3.7. Definition Let ~ F . A point α ∈ F is said to be soft pre-interior ( FA ,τ~1 ,τ~2 ) is soft bitopological space , and FB ⊆ A A FB with respect to the two soft topological spaces τ~1 and τ~2 if there is a soft pre-open FC such that point of ~F α ∈ FC ⊆ B and τ~2 . The set of all soft pre-interior points of FB with respect to the two soft topological spaces τ~1 denoted by Spre-int( FB ). 3.8. Definition Let ( FA ,τ~1 ,τ~2 ) is soft bitopological space . A point α is called soft pre-limit point of soft subset FB of FA with respect to the two soft topological spaces containing another point different from points of α in τ~1 and τ~2 if and only if for each a soft pre-open set FC ~ F ≠ φ . The set of all soft pre-limit FB , that is ( FC /{α }) ∩ B FB be denoted by Spre-lm( FB ). 3.9. Definition 49 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2016) Volume 26, No 4 , pp 42-53 Let ~ F , the intersection of all soft pre-closed sets ( FA ,τ~1 ,τ~2 ) is soft bitopological space , and FB ⊆ A containing FB is called soft pre-closure of FB , and is denoted by Spre-cl( FB ). In the year 2014 J. Subhashinin and Dr. C.Sekar [3] by depending on the [6] and [4] introduces soft pre separation axioms , soft P T -space and some of its properties in the soft topological spaces . Now begin to important section to discuss soft pre separation axioms and some result . 4. The Separation Axioms in Soft Bitopological Space In section four , I introduce some soft pre separation axioms , Spre- T , Spre- T1 and Spre- T2 and illustrate transmission this Properties to The relative soft bitopological space with some result of soft pre separation axioms . 4.1. Definition Let ( FA ,τ~1 ,τ~2 ) is soft bitopological space , then ( FA ,τ~1 ,τ~2 ) is called Spre- T space if and only if for all pair of soft point α2 α1 , α 2 ∈ FA or soft pre-open set such that α1 ≠ α 2 , there exists soft pre-open set FB containing α1 but not FC containing α 2 but not α1 . 4.2. Theorem A soft bitopological space ( FA ,τ~1 ,τ~2 ) is Spre- T space if and only if for each distinct soft points α1 , α 2 in FA , Spre-cl( {α1} ) ≠ Spre-cl( {α 2 } ) . Proof :- Let α1 , α 2 ∈ FA such that α1 ≠ α 2 and Spre-cl( {α1} ) ≠ Spre-cl( {α 2 } ) . Then there exists at least one soft point Suppose α3 in FA such that , α 3 ∈ Spre-cl( {α1} ) but α 3 ∉ Spre-cl( {α 2 } ) . ~ Spreα 3 ∈ Spre-cl( {α1} ) , to show that α1 ∉ Spre-cl( {α 2 } ) . If α1 ∈ Spre-cl( {α 2 } ) , then {α1} ⊂ ~ Spre-cl(Spre-cl( {α } ))=Spre-cl( {α } ) , hence cl( {α 2 } ) . So Spre-cl( {α1} ) ⊂ 2 2 α 3 ∈ Spre-cl( {α 2 } ) which is contradiction . Hence α1 ∉ Spre-cl( {α 2 } ) α 3 ∈ Spre-cl( {α1} ) , consequently , then α1 ∈ FA -Spre-cl( {α 2 } ) but Spre-cl( {α 2 } ) is soft pre-closed , so FA -Spre-cl( {α 2 } ) is soft pre-open which contains α1 but not α2 . It follows that Conversely , since ( FA ,τ~1 ,τ~2 ) is Spre- T space . ( FA ,τ~1 ,τ~2 ) is Spre- T space, then for each tow distinct soft points α1 , α 2 ∈ FA there 50 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2016) Volume 26, No 4 , pp 42-53 exists soft pre-open set α1 but contains contain α2 FB such that α1 ∈ FB , α 2 ∉ FB . FA − FB is soft closed set which does not contain , by definition (3.9) Spre-cl( {α 2 } ) is the"soft intersection of all soft pre-closed"which ~ F − F then α ∉ F − F .This implies that α ∉ Spre-cl( {α } ) . {α 2 } . Thus , Spre-cl( {α 2 } ) ⊂ 2 A 1 B 1 A B So we have α1 ∈ Spre-cl( {α1} ) , α1 ∉ Spre-cl( {α 2 } ) . Therefore Spre-cl( {α1} ) ≠ Spre-cl( {α 2 } ) 4.3. Theorem Every soft subspace of Spre- T space is Spre- T space . Proof :- Let ( FB ,τ~1FB ,τ~2 FB ) be a soft sub space of Spre- T space ( FA ,τ~1 ,τ~2 ) . To prove that the soft sub space is β1 ≠ β 2 ~ F then β ≠ β ∈ F and ( F ,τ~ ,τ~ ) is FB ⊆ A 1 2 A A 1 2 ~ Spre- T space , then there is a soft pre-open set FC in FA , such that β1 ∈ FC , β 2 ∉ FC . So FC ∩ FB is soft Spre- T space , let β1 , β 2 ∈ FB such that . Since ~ F and β ∉ F ∩ ~ F . Hence ( F ,τ~ F ,τ~ F ) is Spre- T space . FB and β1 ∈ FC ∩ B 2 C B B 1 B 2 B pre-open set in 4.4. Definition Let ( FA ,τ~1 ,τ~2 ) is soft bitopological space , then ( FA ,τ~1 ,τ~2 ) is called Spre- T1 space if and only if for all pair of soft point α1 , α 2 ∈ FA , there are two soft pre-open sets FB , FC such that FB contains α1 but not α 2 and FC contains α 2 but not α1 . 4.5. Theorem Every soft subspace of Spre- T1 space is Spre- T1 space . Proof :- Let ( FB ,τ~1FB ,τ~2 FB ) be a soft sub space of Spre- T1 space ( FA ,τ~1 ,τ~2 ) . To prove that the soft sub space is Spre- T1 space , let β1 , β 2 ∈ FB such that β1 ≠ β 2 . Since Spre- T space , then there exists two soft pre-open set β 2 ∈ FD but β1 ∉ FD but FC , FD in FA , such that β1 ∈ FC but β 2 ∉ FC and . Then we obtain two soft set β1 ∈ FC1 ~ F then β ≠ β ∈ F and ( F ,τ~ ,τ~ ) is FB ⊆ A 1 2 A A 1 2 ~ F ,F = F ∩ ~ F are soft pre-open sets in F , we have FC = FC ∩ B D D B B β 2 ∉ FC1 ; β 2 ∈ FD1 1 1 , but β1 ∈ FD1 . Hence 51 ( FB ,τ~1FB ,τ~2 FB ) is Spre- T1 space . American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2016) Volume 26, No 4 , pp 42-53 4.6. Theorem If Every singleton soft subset of soft bitopological space ( FA ,τ~1 ,τ~2 ) is soft pre-closed , then ( FA ,τ~1 ,τ~2 ) is Spre- T1 space . Proof :-This is clearly seen . 4.7. Theorem A soft bitopological space ( FA ,τ~1 ,τ~2 ) is a Spre- T1 space if and only if Spre-cl ({α }) = φ , for each α ∈ FA . Proof :-This is clearly by using prove contradiction . 4.8. Definition Let ( FA ,τ~1 ,τ~2 ) is soft bitopological space , then ( FA ,τ~1 ,τ~2 ) is called Spre- T2 space (Spre-Hausdorf) if and only if for each pair of distinct soft point that α1 ∈ FB , α 2 ∈ FC α1 , α 2 ∈ FA , there exists two soft pre-open sets FB , FC in FA such ~ F =φ . FB ∩ C and 4.9. Theorem Each soft subspace of Spre- T2 space is Spre- T2 space . Proof :- Let ( FB ,τ~1FB ,τ~2 FB ) be a soft sub space of Spre- T2 space ( FA ,τ~1 ,τ~2 ) and let FB ≠ φ be a soft subset of FA , and α1 ≠ α 2 ∈ FB then α1 , α 2 ∈ FA , since ( FA ,τ~1 ,τ~2 ) is Spre- T2 space ,there exists two soft pre~ ~ ~ open sets FD , FC in FA such that α1 ∈ FD , α 2 ∈ FC and FD ∩ FC = φ . So FD ∩ FB , FC ∩ FB are soft pre-open sets in FB ~ F ,α ∈ F ∩ ~F α1 ∈ FD ∩ 2 B C B and ; ~ F )∩ ~ (F ∩ ~ F ) = (F ∩ ~ F )∩ ~ F = φ . Hence ( F ,τ~ F ,τ~ F ) is a Spre- T space . ( FD ∩ 2 2 B B 1 B B C B D C B 4.10. Theorem Each singleton soft subset of Spre- T2 space is a soft pre-closed . Proof :-This is clearly seen . 52 and American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2016) Volume 26, No 4 , pp 42-53 5. Conclusion In the conclusion of a work paper , many of the basic concepts on soft bitopological space , introduced soft bitopology . Furthermore , introduced relative soft bitopological space , soft pre-open set and some definitions on bitopology by"soft pre-open set as (soft pre-closed , soft pre-neighborhood , soft pre-interior ,soft pre-limit point and soft pre-closure) these"definitions using in other sections from the work and introduce some soft pre separation axioms and studied Properties on soft bitopological space with some important results, one could study the soft ideal bitopology and get some important results too . References [1] Basavaraj M. Ittanagi , Soft Bitopological Spaces , International Journal of Computer Applications , Volume 107 , No. 7, December 2014. [2] D.A. Molodtsov ,Soft set theory-first results , Computers and Mathematics with Applications 37 (1999) 19-31. [3] J.Subhashini and C.Sekar , Soft pre T1 Space in the Soft Topological Spaces , International Journal of Fuzzy Mathematics and Systems , Volume 4 , Number 2 (2014) , pp. 203-207. [4] J. Subhashinin and Dr. C. Sekar , Local properties of soft P-open and soft P-closed sets , Proceedings of National Conference on Discrete Mathematic and Optimization Techniques (2014) 89-100. [5] Naim Cagman and Serdar Enginoglu , Soft set theory and uni-int decision making , European Journal of Operational Research 207 (2010) 848-855 [6] Naim Cagman , Serkan Karatas and Serdar Enginoglu , Soft topology , Computers and Mathematics with Applications 62 (2011) 351-358 . [7] Sabir Hussain and Bashir Ahmad , Some properties of soft topological spaces , Computers and Mathematics with Applications 62 (2011) 4058-4067 . 53
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