具有"null"的个人对象属性 [英] Individual with "null" object property

问题描述

我正在Protege中进行本体任务.

I am working on an ontology task in Protege.

情况:我有Student class，其子类为InactiveStudent，ActiveStudent和VeryActiveStudent.这些子类具有与称为isEnrolledForSubject的对象属性有关的条件.我为以下条件定义了条件:

Situation: I have Student class that has subclasses of InactiveStudent, ActiveStudent and VeryActiveStudent. These subclasses have conditions related to object property called isEnrolledForSubject. I defined conditions for:

ActiveStudent = 'Class of all students' and (isEnrolledForSubject min 1 'Class of all subjects')

VeryActiveStudent = 'Class of all students' and (isEnrolledForSubject min 4 'Class of all subjects')

但我不知道如何为InactiveStudent定义它-条件是该学生尚未注册ANY subject.事实是，当我定义一个John时，我不能对他说"isEnrolledForSubject null"，因此他不能进行对象属性声明，因为Protege的向导期望的是定义范围内的一个人.

but I don't know how to define it for InactiveStudent - the condition is that such student has not enrolled for ANY subject. The thing is, that when I define an individual John I cannot make object property assertion on him saying "isEnrolledForSubject null", because Protege's wizard is expecting a individual from defined range.

如何解决这种情况?

推荐答案

您的定义如下:

InactiveStudent = 'Class of all students' and (isEnrolledForSubject max 0 'Class of all subjects')

然后，当您定义inactiveStudent个人时，您需要按以下说明进行声明:

Then when you define a inactiveStudent individual, you will need to state it as follows:

inactiveStudent Type 'Class of all students'
inactiveStudent Type isEnrolledForSubject max 0 'Class of all subjects'

其原因归结于两个因素:

The reason for this is due to 2 factors:

(1)对象属性定义2个个人之间的关系.除了像我一样限制自己的类型之外，没有办法说不的某个人与任何其他人的关系.

(1) Object properties defines relations between 2 individuals. There is no way to state that an individual in not in a relation with any other individual besides by constraining its type as I did.

(2)如果一个人没有通过对象属性链接到另一个人，则由于开放世界假设而无法推断出更多内容.非正式地，这意味着推理者可以从本体进行的唯一推断是基于本体中陈述的显式信息或可以从显式陈述的信息中得出的内容.

(2) If an individual is not linked to another individual via an object property, nothing more can be inferred due to the open world assumption. Informally it means that the only inferences that the reasoner can make from an ontology is based on explicit information stated in the ontology or what can derived from explicit stated information.

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