A Technology Of Transformation From Ontology Description Language OWL To Prolog

Berners-Lee brought up the conception of Semantic Web in order toshare the information resource in web at semantic level. The technology ofsemantic web is becoming a focus of current research in internet technology.The aim of semantic web is to develop a series of new technologies andchange the current mode sharing the resource by word information intointelligent and automatic internet services by semantic sharing andoperations.At present, the researches of semantic web are focused on Ontology,which defines conceptions precisely by strict definitions and relationsbetween conceptions. So ontology, the base of web information sharing andinterchanging, is very important in semantic web research. Ontologyemphasizes the data sharing, in other words, the data described by ontology isaccepted by other people is not individual but general. The technology ofontology relies on knowledge representation and reasoning technology justlike other artificial intelligence technologies.OWL, an ontology description language, is based on XML, RDF andRDFSchema. Compared with XML, RDF and RDFSchema, there are moremethods to describe semantics in OWL. At present, OWL, which has beenconsidered as the web ontology standard, is formally recommended by W3C.The aim of OWL is to provide a standard language to describe files, classesand relations in order to support the semantic applications in web. However,OWL is only a description language or a knowledge representation so it cannot be reasoned or calculated alone. In other words, it means nothing withoutan inference engine. If only the inference engine reasons the description, itmakes sense.In this thesis, the reasoning technology is accomplished by transformingOWL into a programming language based on logics named Prolog, by whichway the powerful reasoning functions of Prolog can be entirely used.There are three subsidiary languages in OWL: OWL Lite, OWL DL andOWL Full. The expressive abilities of them are increased progressively,among which OWL Lite is the weakest one. So the development ofsupportive tools based on OWL Lite is easier, and these tools can be extendedto OWL DL. OWL Lite is considered as a kind of description logic, ontologyis just like the knowledge database of description logic. Description logic hada great effect on the design of OWL, especially in semantic aspect, so thereasoning can be accomplished by transforming OWL into description logicsystem. However, some difficult problems can not be described bydescription logic, or the description is too huge to be reasoned. Prolog withmany powerful functions is a widely-used reasoning tool. It contains aninference engine, which reasons information logically. Based on thesereasons, the reasoning is accomplished by transforming OWL Lite to Prolog,in other words, using Prolog to reason OWL Lite descriptions.Prolog is the most famous artificial intelligence language, with manypowerful functions. It contains an inference engine, which reasonsinformation logically. When people program using Prolog, they do not carethe process of solving problem but the description of problem. Prolog isbased on Horn subsidiary sentence, which is the subset of predicate logic andprovides a comprehensible syntax, just like the nature language. Prologcontains an inference engine. The inference engine contains a mode matchingmachine, which retrieves given information by matching answers andquestions. Prolog infers a true conclusion from inquiring the set of trueinformation. The known domain in Prolog is the set of given limited facts inprogram.Before the transformation, some prepared work has been done. TheOWL was written in BNF mode in order to do phrasal, syntactic and semanticanalyses;the syntax tree based on OWL and all kinds of chains and nodeswere designed;the corresponding relation between OWL and Prolog wasdesigned in order to write transformation program in Java, transform OWLdescription into Prolog program and accomplish the OWL reasoning;thestructure of Prolog program was designed in order to receive the inquiriesfrom users.The transformation of OWL according to corresponding structure is themost important work in this thesis. First, OWL transformation program, theOWL file was transformed into Prolog program. Meanwhile, XML phrasal,syntactic and semantic analyses are been done, and produced a syntax treebased on XML. Second, XML syntax tree is retrieved all over andtransformed into a new tree base on OWL. Meanwhile, OWL phrasal,syntactic and semantic analyses are been done. If there is no error, Prologprogram is produced. Third, user's inquiries are added into the goalparagraph of Prolog program. Finally, the Prolog program is compiled andran in order to get the answer.This thesis accomplished the whole transformation from OWL to Prolog,but there are some faults. For example, only the OWL Lite was talked, theimport of ontology were not mentioned, some restrictions were made in orderto make the programming more convenient.