owl
How is it possible to perform Metamodelling in Protégé
Metamodelling happens if an IRI is used as a class and as an individual in two axioms. The topic is described at http://www.w3.org/TR/owl2-syntax/#Metamodeling.
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Object properties shall be a sub class of owl:Class
Making owl:ObjectProperty a subclass of owl:Class alows any object property to be the object of the owl:range and the owl:domain predicate. In "Paul takes Paul's car to reach Paul's office" therefore the predicate "takes" can be used as a owl:range and a owl:domain. Moreover, members of object properties can be used as anonymous individuals.
The following statement should be thus become possible in OWL2 syntax:
DataPropertyAssertion (rdf:ID (ObjectPropertyAssertion (:takes :Paul :PaulsCar) _:L1)
ObjectPropertyAssertion (:toReach _:L1 :PaulsOffice)
Based on this approach the number of classes and object properties is reduced by 25% and the number of associations triples by approx. 33%
Semantic Web does not provide reference to object properties
Semantic web knowledge representation is build on triples, which represent subject - predicate - object. Semantic web Standards are using those triples as atomic building blocks for their own specification and any ontology.
With triples knowledge can be specified like in the sentence: "Paul is a Person". "Paul" is the subject, "is a" is the predicate, "Person" is the object.
Subject and object are considered as entities while predicates are considered as object properties are connecting those entities. From this perspective representation of every knowledge is quiet similar to the usage of early days' entity-relationship-diagrams. Also some shortcomings seem to be adopted.
Sentences like: "Paul takes Pauls Car to reach Pauls Office" cannot be described easily. It requires an intermediate, unnatural entity like "Pauls Vehicle Choice" and many sentences: "Pauls Vehicle Choice chosen by Paul", "Pauls Vehicle Choice is Pauls Car", "Pauls Vehicle Choice reaches Pauls Office". Instead of one sentences there are three sentences for describing the equivalent problem.
Isn't there an alternative approach possible?
programming with OWL API
-What is OWLAPI
-Why we need OWL API
-How can we use OWP API
-Example
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Installing Protégé on MacOs leopard
My solution was to bypass the problem by using the windows-simulation and the windows-installation file of protégé.
But that's not the solution, I'm very happy with, so I'm still searching for a better one!
I'm thankful for input!
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Installing Protégé on MacOs leopard
When I tried to install the Protégé editor on my MacOS leopard system from the following link, I was able to download it, but I couldn't open the install-file.
http://protege.stanford.edu/download/protege/3.4/installanywhere/
How to visualize an ontology
Finding a tool to visualize an ontology's structure is what this challenge is all about. It should be as simple and intuitive as possible, and, if possible, free of charge. It should be able to handle at least one of the standard ontology standards (e.g. OWL).
Protégé Server
<p>To enable an access for a community to develop an ontology a server based solution is required. WebProtégé offers such a solution but must be installed on an application server.</p>
How to store ontologies in a relational database?
The Semantic Web brings closer to realization the possibility of semantically organized data repositories, or ontologies, throughout the Internet that can be used for intelligent information searching both by humans and computational agents. Ontologies are important to application integration solutions. However, while today there is an un-precedented wealth of information available on the Web, to fully realize the power of ontologies and to enable efficient and flexible information gathering, persistent storage of ontologies and its subsequent retrieval is of paramount importance. Therefore, storing ontologies in a relational database is one way to get around this problem.
What's a proper programming language for Semantic Web reasoning?
As I already mentioned, the internet is one big database. But how much is the information worth? Obviously not all the information on the internet is true and not all information is worth to be taken into consideration by solving problems.
As I see it, the Semantic Web is still in its child shoes. New technologies and ideas come up, each and every day. The progress of structuring date using W3C recommendations has just begun. That allows to make more and more data being read- and understoodable by machines. But in the end, intelligent software (e.g. agents) has to do some kind of reasoning to solve their given problems. The software has to decide on its own, which information is worth to be taken into consideration and which information isn't. Moreover, the software has to decide how to use the given data.
Logic Programming is one way to go. Lot's of (semantic web related) artificial intelligent and search problems could be solved by Logic Programming technologies such as Answer Set Programming (ASP). The simpleness and elegancy of ASP may perfectly fit to Semantic Web tasks, such as information collection and interpretation from standardized Semantic Web knowledge bases or intelligent software design.
Does there already exist some languages that fulfills this description? Does there exist logic programming languages that are able to be used with modern Semantic Web technologies, such as XML, RDF and OWL? Yes it does.....
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