Adding synonyms to concepts in ontology to solve the problem of semantic heterogeneity

Synonyms are words with the same or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. An example of synonyms are the words “begin” and “commence”. Likewise, for term a“long time” or an “extended time”, “long” and “extended”, “buy” and “purchase”, “big” and “large”, “quickly” and “speedily”, “hospital” and “infirmary”, “on” and “upon” become synonyms.


I. Introduction
Synonyms are words with the same or similar meanings.Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy.An example of synonyms are the words "begin" and "commence".Likewise, for term a"long time" or an "extended time", "long" and "extended", "buy" and "purchase", "big" and "large", "quickly" and "speedily", "hospital" and "infirmary", "on" and "upon" become synonyms.
Other example is term "poverty".For some people that already have a knowledge and information about poverty can easily say that poverty is the state of one who lacks a certain amount of material possessions or money.For other people, "Poverty" refers to the deprivation of basic human needs, which commonly includes food, water, sanitation, clothing, shelter, health care and education.Regardless of the various definitions of poverty, this paper will focus only on terms related to the reality of "Poverty".Figure 1 shows that "Poverty" related with many things (terms) such as "Shelter", "Food", "Sanitation", "Health", and "Asset".
It can be said that every reality will be represented by a variety of terms associated with it (Fig. 1).Ontology is one of the solution for the semantic integration problem [1], [2].The ontology integration and ontology interoperability can be applied by discovering semantic correspondences [3] among a set of formal ontologies and (sometimes) creating a more complete ontology given that multiple source ontologies are available.Some of the most representative ontology definitions are: (1) Ontology as an explicit specification of a conceptualisation [4] , (2) Ontology is a formal description of entities, properties, relations, constraints and behaviours [5], and ontology is a formal explicit description of concepts in a discourse domain, where properties of each concept describe several characteristics, attributes of concepts and attributes' constraints [6] .It can be concluded that Nowadays many department (community) are thinking how to get more knowledges and metadata by linking more systems from other community.There are great challenges to make all systems organizing knowledge and sharing metadata -to make it easy searched, indexed and used in different context.In this paper we will focus on metadata in specific domain -'Poverty'2.Regardless of the various definitions of poverty, in this paper we will focus on managing metadata in "Poverty" with many different terms therein.Ontology Mapping is the process of relating similar concepts or relations from different sources through some equivalence relation.Mapping allows finding correspondences between the concepts of two ontologies.If two concepts correspond, then they mean the same thing or closely related things.Currently, the mapping process is regarded as a promise to solve the problem between ontologies since it attempts to find correspondences between semantically related entities that belong to different ontologies.It takes as input two ontologies, each consisting of a set of components (classes, instances, properties, rules and axioms).Based on the presented reasons, we believe that ontologies with common terms and common concepts are very important in a metadata sharing process.
the issue of synonyms become the focus in this paper.The use of terms in each system is very dependent on each programmer, it does not become a problem until the system A and system B will be integrated.The main problem is how to equate the terms in both systems.As an example in the case study "Poverty".System A and system B refers term "Poverty" as the deprivation of basic human needs.System A uses the term "Money", "Food", "Water", "Sanitation", "Asset", "Clothing", and "Shelter".System B uses the term "Salary", "Feed", "Water", "Sanitation", "Property", "Clothing", and "House".Synonyms are words with the same or similar meanings.An example of synonyms are the words "Money" and "Salary" and "Wage".Likewise, for the term an "Asset" or an "Property", "Food" and "Feed", "House" and "Shelter", "People" and "Person" become synonyms.This paper is organized as follows:  An architecture system is a sets of developing steps for designing system.Fig. 2 shows an architecture process of the system : Block 1 understanding of the realities of a domain, Block 2 building ontologies, Block 3 intergating ontolgies with mapping techniques, Block 4 illustrates this in an interface.The first block (Block 1) in an arsitecture system.Reality (actual state of the domain) support the emergence of data (fact about the domain).Information can be considered as an aggregation of data (processed data) which makes decision making easier.Information has usually got some meaning and purpose.Knowledge is derived from information in the same way information is derived from data.Knowlege is ussulay appear based on learning, thinking and proper understanding of the problem area.Block 1 shows the reality from domain x, reality can produces a variety of perceptions such as perception a, perception b, and perception c of a reality, next step perceptions stored in a data base (db1, db2, and db3) in each system.Each end user make a query based on the knowledge that they have.In accordance with the objectives of this dissertation, the first step that must be done is to manage the data into knowledge.Table in a data base managed into classes in knowledge base ontology .The process is done manually.Furthermore, the problem faced after ontology is made.Ontology a, ontology b, and ontology c consists of different name/term of classes, different name/term data properties, different name/term object properties and different name/term instances wich depends on the data source in the data base.
Example : (Poverty Domain) Ontology a from institution A: "Normally all family members have meal two or more times a day".Ontology b from Institution B: "Minimum two times per day the family have food" Meal and food have the same meaning, as well as suit and clothes or clinic and hospital.To be similar (≅) or not equal (≠) depend on several factors, such as the programmer's interpretation, the needs of the system itself, and the domain/area.each term has always a strong relationship with the domain.
Block 2 and block 3 carried out mapping classes, properties, and instances between ontologies.The target is to combined different existing terminologies about the same reality used by different communities in order to get a common set of terms that can be transparently used by those communities, while maintaining the original terms in the data sources .A single ontology is no longer enough to support the tasks envisaged by a distributed environment.Multiple ontologies need to be accessed from several applications or systems.Ontology mapping is required for combining distributed and heterogeneous ontologies.?Person :hasRarelyEat ?FoodConsume.?Person :hasJobPositionAs ?Job.?Person :hasFloorMaterial ?Floor.?Person :isLivinginVillage ?Area.hasRarelyEat, hasJobPositionAs, hasFloorMaterial, and isLivinginVillage are some of ObjectProperties that are use in this ontology.
Another example : Knowledge in Institution B (here we called UV2) refers poor people as a people lack in Food, Job, House (hasLargestFloorAreaMadeFrom) Condition.In Ontology UV2 we build some classes such as Class Person, Class FoodConsume, Class Job, Class Floor and Class GeographicArea.Next step, Class Person will be connected with other classes, such as Class Food, Class JobArea, Class Floor, and Class GeographicArea.hasRarelyEat, hasJob, hasHouseFloorMadeFrom, and isLivinginSubDistrict are some of ObjectProperties that are use in this ontology.Furthermore ObjectProperties is used to connect any classes related.

III. Testing Ontology Model
Testing and evaluation of the results performed on a ontology model prototype which has been built in SPARQL testing (expert) where the testers who understand SPARQL language can perform manual testing by input SPARQL query.Here's an example of testing prototype application of ontology model for poverty case study.Testing covers 11 classes in Ontology UV1 (Area, Assets,Contraceptive, Education, FoodConsume, GovermentAid, HealthProblem, Hospital, HouseCondition, Job, Person) , 12 Classes in Ontology UV2 (Asset, BirthControlMethod, EducationLevel, Food, GeographicArea, GovHelp, HealthCondition, Hospital, HouseParameter, JobArea, Person, Work), are being integrated with classes in Ontology CO (People, Property, House, Work, Area, BirthControl, Health, Education, Hospital,Food).Testing also covers 67 Data Properties, 22 Object Properties, consist of more than 600 intances from Ontology UV1.Ontology UV2 42 Data Properties, 43 Object Properties, consist of more than 450 intances.Ontology CO covers 33 classes, 84 Object Properties, 121 Data Properties, and consist of more than 1500 instances (Table 1).

Fig. 2 .
Fig. 2. Proposed Model B. Example of SPARQL query Ontology UV1 consist of some classes such as Class Person, Class FoodConsume, Class Job, Class Floor and Class Area, each classes are related to each other.