Fininding foaf instances

Foaf is a well-known semantic web practice on the Web, and we know that there are millions of FOAF instances on the Web. A scutter can help use to recursively find foaf documents online using hyperlinks in foaf documents; however, how to obtain the initial seeds is still a big issue.

In addition, many semantic web users would like to find out the population of ontology, e.g. the instances of a defined class such as foaf:Person, or where foaf:email has been populated as predicate.

Therefore, Swoogle provide an interesting interface supporting finding instances of a class such as foaf:Person.

This swoogle query searches the usage of a semantic web term, foaf:Person.

Meaning?
Its result consists of six exclusive categories:

• definesClass: the term has been defined as a class in the ontology
• definesProperty: the term has been defined as a property in the ontology
• populatesClass: there is a class-instance of that term in the document
• populatesProperty: the term has been used as a predicate (i.e. populated) in the document
• usesClass: the term has been used (neither defined or populated) as a class in an document. e.g. when an ontology asserts myns:Person rdfs:subClassOf foaf:Person.
• usesProperty: the term has been used as a property

Note that a document might have multiple usage relation with a term, e.g. a document both defines a term as a class, uses it to define other classes and properties, and populates its class-instances.

How to get there
In order to access that page, please follow the following steps:

1. start from swoogle home page, choose “search term”
2. type the localname or the entire URI surrounded by double qoute, and move to search result page
3. click “metadata” link under your URI, and move to term’s metadata page
4. click “related documents” link (a grey block) on the top of the page, and move to the wanted page

NOTE: advanced users may use swoogle web service APIs to retrieve more results.