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我正在使用 FaCT++ 和一个简单的本体研究 Protege 4 的 OWL 限制概念。假设我有一个foo班级个人Something：

:Something a owl:Class.
:foo a :Something, owl:NamedIndividual.

以及从对hasBar属性的限制定义的另一个类：

:hasBar a owl:ObjectProperty.
:SomethingElse owl:equivalentClass [a owl:Restriction;
                                    owl:onProperty :hasBar;
                                    owl:allValuesFrom :Something].

如果我断言：

:x :hasBar :foo.

为什么我不能从中推断出x是 a SomethingElse（通过事实foo是 a Something）？我可以使它工作的唯一方法是定义rangeof ：hasBar

:hasBar a owl:ObjectProperty;
        rdfs:range :Something.

但我想避免这种情况，因为它限制了可以成为主题的内容hasBar（这给我带来了更多麻烦）。

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1 回答 1

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I think it is simpler to reason over real examples, let's consider the following knowledge base:

:eats rdf:type owl:ObjectProperty .

:Vegetable rdf:type owl:Class ;
       rdfs:subClassOf owl:Thing .

:Vegetarian rdf:type owl:Class ;
        owl:equivalentClass [ rdf:type owl:Restriction ;
                              owl:onProperty :eats ;
                              owl:allValuesFrom :Vegetable
                            ] .

:Carrot rdf:type :Vegetable ,
             owl:NamedIndividual .

:John rdf:type owl:NamedIndividual , owl:Thing ;
      :eats :carrot .

You have some equivalences with your example: hasBar is eats, Vegetarian is SomethingElse, Vegetable is Something, foo is carrot and finally x is John.

Now you would like to infer that John is a Vegetarian (= x is SomethingElse).

It makes sense that it doesn't work with an owl:allValuesFrom. What you are saying here is that all instances of vegetarian, if they have a property, they must have Vegetable in range. So from that you could deduce that carrot is a vegetable for example, assuming you would know that John is a vegetarian in the first place.

It makes sense in natural language too: In your ontology you only know that John eats a carrot, this doesn't automatically make him a vegetarian (non-vegetarian people eat also carrots).

You could use a owl:someValuesFrom instead of a owl:allValuesFrom. This way, you would define every vegetarian has someone that eats some vegetable. In this case if we know that John eats a carrot, therefore he would be classified as vegetarian by the reasoner, based on your definition of the concept vegetarian.

Universal (allValuesFrom) and existential (someValuesFrom) restrictions are complicated to understand, there is often no right or wrong solution, it mostly depends to what you want to achieve.

于 2013-04-16T09:08:04.330 回答