How do you normalize an ontology the way you would normalize a relational database?

I know how to normalize a relational database. There are methodologies for getting to a fif开发者_运维知识库th normal form. I understand the reasons why you may want to back off to fourth normal or otherwise.

What is the equivalent method for an ontology which describes a graph?

I am not aware of any mechanism for ontologies that is directly comparable to database normalization. The closest match I can think of are ontology design patterns. However, they are much less strict. You can roughly compare them to software design patterns. You can check

http://ontologydesignpatterns.org/wiki/Main_Page

or have a look at some papers, e.g., about the M3O (http://dl.acm.org/citation.cfm?id=1772775), Event Model F or by Aldo Gangemi, among many others. Ontology design patterns also give you certain properties, but they mainly depend on the patterns you use, and which ones are appropriate depends on the modeling taks you try to achieve.

Both design patterns and database normalization try to achieve certain properties. I guess the difference is, that design patterns are less strict. The achieved properties are often depending on the patterns you use, the domain, the purpose etc. So, they are not really as generic as the normal forms.