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Top1. Introduction
Usually, computers were used to perform tasks with none sort of intelligence or semantics thus there is a necessity to make computers as intelligent as human (Antoniou & Van Harmelen, 2004). The defect of non-Semantic applications is painted by the statement “lack of semantics” particularly when the talk is concerning information retrieval. The semantic web’s goal is to extend automation in processing web-based data and to enhance the interoperability of web-based information systems (Payne, Terry & Lassila, 2004). The semantic web gives the meaning of knowledge making software systems can perform intelligent tasks instead of users (Berners-Lee, Hendler & Lassila, 2001) using a semantic knowledgebase called Ontology. Ontologies is a repository in which information are organized and used in semantic-based applications (Shadbolt, Berners-Lee & Hall, 2006). Below a group of definitions that may be used as a basis for mathematical formulation of the term ontology and its components (Fonseca, Davis & Câmara, 2003):
Definition 1: A term is a triple τ = [η, δ, Α], τ ∈ Τ, where η is a string of characters containing the name of the term, δ is a string of characters containing its definition and Α is a set of attribute domains A1, A2, ..., An, each associated to a value set Vi.
Definition 2: A relation φ: Τ → Τ, φ ∈Φ: is a function from Τ to Τ such that for every term τ1∈Τ, there is a term τ1 = φ (τ1), τ2∈Τ.
Definition 3: A semantic relation σ between two concepts is one of the relations among the set of semantic relations Σ = {Hypernym, Hyponymy (is-a), Meronomy (part-of), Synonymy}. In linguistics, a hyponym is a word whose semantics is enclosed inside that of another word which called its hyperonym or its hypernym. In other words, a hyponym has the same a type-of relationship with its hypernym. For instance, dog, cat and cow are all hyponyms of Mammals (their hypernym); that, in turn, could be a hyponym of animal (Fromkin, Rodman & Hyams, 2013).
Ontologies are often used in many systems as a semantic knowledgebase (Oberle, 2014). In the field of health informatics, ontology is used for the representing and organizing medical vocabularies. Collins and Loftus (1975) discussed in their research that the Spreading Activation (SA) runs on semantic networks (Anderson et al., 1983) and is used for information retrieval process (Burnset et al., 1981). It runs on a graph structure that comprises of a set of nodes connected by edges. The concepts are nodes which have an activation value and the relations between them are represented by edges between these nodes. An activation value is assigned to each node in the graph and then the algorithm spreads to the nodes with the higher activation value. The algorithm runs in a set of iterations and terminates when a stopping condition is reached.
The main objective of this work is to identify whether two human diseases are related to each other or not. If so, identify the set of diseases that connecting them. Finding a relatedness between diseases is important because the doctor can treat patient not only based on the symptoms they suffer from but treat the real cause of this disease which may be related to another disease that causes these symptoms therefore, the doctor can treat the cause disease not the symptoms.
This paper is organized as follows. Section 1 gives a brief overview of semantic web and ontologies. Section 2 reviews the literature. Section 3 describes the ontology for SAOO. Section 4 introduces the methodology of the proposed work. Section 5 illustrates the methodology by showing a running example. Section 6 describes the prototype used to implement the methodology. Finally, Section 7 presents conclusions and future work.