USING UMBEL

UMBEL can be used in a myriad of ways; here we describe some of them, but its utility is not limited to them.

Using UMBEL to Describe Things

UMBEL can be used to describe things. Considering the current sparse nature of the ontology space, UMBEL can be used to fill some gaps. The goal is to use UMBEL reference concepts to describe certain individuals belonging to their governing reference concept classes.

By using UMBEL, you can find a reference concept related to any thing you may wish to describe. Once the proper reference concept is found (if it exists), you can then check the structure to try to re-use classes and properties defined in external ontologies to describe that thing you want to describe in RDF.

In such a scenario, it is the upper ontology facet of UMBEL that is exploited. There is an example:

We want to describe the person of Muhammad Ali. However, we don't want to describe him only as a simple person; since he is the best boxer of the 20^th century, we want to describe him as a boxer! But we can't find any "boxing ontology". Normally, this would mean that we would have to describe Ali as a person (foaf:Person), or we would have to define a new "boxing ontology". But, with the capabilities of UMBEL, we can now search for a reference concept "boxer" in UMBEL and use it as well to describe Muhammad Ali.
If we use the Find Subject UMBEL Web service, we will find that the reference concept "boxer" exists in UMBEL . We know that a rc:Boxer is a foaf:Person. We have a list of properties, defined in external ontologies, that we can use to describe Ali. This means that we can describe Muhammad Ali this way:

  <http://www.ali.com/me/> a rc:Boxer ;
      foaf:name “Muhammad Ali” ;
      foaf:gender “male” ;
      foaf:birthday “1942-01-17” ;
      ...

This is a good example of how UMBEL can be used as an upper ontology to fill the gaps when specialized ontologies do not exist for a given domain.

Using UMBEL to Help Develop New Ontologies

The notion of consistency testing provided by the use of OWL 2 can be applied to the UMBEL reference concept structure when the need arises to develop new ontologies. UMBEL helps to learn more about a domain of knowledge, and that then leads to develop better ontologies.

Since most of the time an ontology interacts with external ontologies by referring to them, or by re-using some of their classes and properties, having a consistent framework that puts all the ontologies in context helps a lot to define new coherent ontologies and to fix existing ones.

The SKOS specification document ^[1] says:

The OWL 2 schema language helps us to link external ontology classes to UMBEL reference concepts. The consistency/inconsistency concepts are useful to find if a linkage fits, or not, with the defined UMBEL reference concept structure. The UMBEL Web services and the linkage method helps to develop new ontologies and to fix existing ones.

Using UMBEL to Put Individuals in Context

An individual belongs to a class. Since UMBEL is a reference concept structure of well-defined classes with links to classes defined in external ontologies, we can learn a lot about an individual simply by looking-up its type(s) in UMBEL.

This is what we sometimes call the "context" of an individual.

Let's again take the example of Muhammad Ali. Think about someone that gets the RDF description of Muhammad Ali shown in Table 1 above. This person may not know what a "boxer" really is. Then he chooses to look for the type rc:Boxer in UMBEL ^[2]. Only with this search within UMBEL, he knows that: a rc:Boxer is a foaf:Person, a foaf:Agent and a cyc:Boxer. He also finds that Antonio Ayala Jr., Galveston Giant and John Ruiz were boxers too. He now knows that Ali is an athlete and a social being and so on. With a single lookup in UMBEL, the context around Muhammad Ali starts to emerge and its domain explodes.

The Ali example took a reference concept as the lookup basis. However, we could also take an external ontology class to get the same result.

Try the same experiment with a po:Radio ^[3]. We find that it is a rc:RadioStation-Organization ^[4], a foaf:Organization; we find that there exist different types of radio stations such as local radios, regional radios and national radios; we find that WNSC, WRHS, WKHX, WALR-FM are radios organizations, etc. In a single lookup, we get the context of a class described in an external ontology and we explode its domain.

USING UMBEL WEB SERVICES AND TOOLS

UMBEL Web services may be found at http://umbel.org/web-services/. This section describes them and their use. Links below provide examples and syntax for direct querying of endpoints. Depending, the Web service may return results in up to four different serialization formats:

• N-Triples
• RDF+XML
• structJSON
• Clojure code.

URI Dereferencing

All URIs in the UMBEL reference concept structure (concepts + vocabulary) are dereferencable on the web. Dereferencing means you can get a lookup on the Web for the description of the reference concept resource. Any subsequent system or agent that gets the link to an UMBEL reference concept can then determine the meaning of that concept via this dereferencing.

A UMBEL reference concept URI looks like: http://umbel.org/umbel/rc/Person

Lookups

The Search Web service is used to find UMBEL reference concepts that match a search string. This is the primary tool for finding available concepts in the reference structure.

The Get Concept Web service is used to get the full description of a UMBEL Reference Concept. By querying this Web service endpoint, you will get the preferred label, all the alternative labels (namely, the items in the semset, the sub/super classes of the concept, the broader/narrower concepts and the description of that concept.

The Get Super Type Web service is used to get the full description of a UMBEL Super Type. By querying this Web service endpoint, you will get the preferred label, all of the alternative labels, the description, and the disjoint super types of a target super type.

Inference Engines

The Get Narrower Concept Web service is used to get the list of all the narrower concepts of a given reference concept. This processing is done by inference, which means that if A -> B -> C are narrower concepts, then the narrower concepts of A are both B and C, which is what will be returned by the endpoint.

The Get Broader Concept Web service is used to get the list of all the broader concepts for a given reference concept. This processing is done by inference, which means that if A -> B -> C are broader concepts, then the broader concepts of C are both A and B, which is thus what will be returned by the endpoint.

The Get Sub Classes Web service is used to get the list of all the sub classes of a given reference concept. This processing is done by inference, which means that if A -> B -> C are sub classes, then the sub classes of A are both B and C, which is what will be returned by the endpoint.

The Get Super Classes Web service is used to get the list of all the super classes of a given reference concept. This processing is done by inference, which means that if A -> B -> C are super classes, then the super classes of C are both A and B which is what will be returned by the endpoint.

Taggers

The Concept Tagger Plain Web service uses UMBEL reference concepts to tag an input text or a Web document. The OBIE (Ontology-Based Information Extraction) method is used, driven by the UMBEL reference concept ontology. By plain we mean that the words (tokens) of the input text are matched to either the preferred labels or alternative labels of the reference concepts. The simple tagger is merely making string matches to the possible reference concepts.

The Concept Tagger Noun Web service uses UMBEL reference concepts to tag an input text or a Web document. The OBIE (Ontology-Based Information Extraction) method is used, driven by the UMBEL reference concept ontology. By noun we mean that the tagging only occurs with the words (tokens) that are considered singular or plurial nouns in the sentence(s) of the input text. The nouns are matched to either the preferred labels or alternative labels of the reference concepts, with the match basis denoted by color. The simple tagger is merely making nouns string matches to the possible UMBEL reference concepts.

Graph Analysis

The Distance Web service is used to get the distance (measure of distance) between two UMBEL reference concepts by following the path of a transitive property.

The Shortest Path Web service is used to get the shortest path between two UMBEL reference concepts by following the path of a transitive property. The concepts that belong to that path will be returned by the server.

ENDNOTES

1. ↑ http://www.w3.org/TR/2008/WD-skos-reference-20080125/
2. ↑ http://umbel.structureddynamics.com/view_detailed.php?concept=Boxer
3. ↑ http://www.bbc.co.uk/ontologies/programmes/2008-02-28.shtml#Radio
4. ↑ http://umbel.org/refconcept?uri=http://umbel.org/umbel/rc/RadioStation_Organization&ontology=file://localhost/data/ontologies/files/umbel.org/umbel_reference_concepts.n3