Define semantics example

This is written in response to a But if the GGG emerges it may or may not be semantic. For example social networks are NOT semantic today, even though they contain various kinds of links between people and other things.

So what makes a graph “semantic?” How is the semantic graph different from social networks like Facebook for example?

Many people think that the difference between a social graph and a semantic graph is that a semantic graph contains more types of nodes and links. That’s potentially true, but not always the case. In fact, you can make a semantic social graph or a non-semantic social graph. The concept of whether a graph is semantic is orthogonal to whether it is social.

A graph is “semantic” if the meaning of the graph is definedand exposed in an open and machine-understandable fashion. In otherwords, a graph is semantic if the semantics of the graph are part ofthe graph or atleast connected from the graph. This can be accomplished by representing a social graph using RDF and OWL, the languages of the Semantic Web.

Today most social networks are non-semantic, but it is relatively easy to transform them into semantic graphs. A simple way to make any non-semantic social graph into a semantic social graph is touse the FOAF ontology to define the entities and links in the graph.

FOAF stands for “friend of a friend” and is a simple ontology of peopleand social relationships. If a social network links its data to theFOAF ontology, and exposes these linkages to other applications on theWeb, then other applications can understand the meaning of the data inthe network in an unambiguous manner. In other words it is now asemantic social graph because its semantics are visible to otherapplications.

As illustrated by the FOAF example above, one way to make a graphsemantic is to use the W3C open standards for the Semantic Web (RDF andOWL) to represent, and define the meaning of, the nodes and links inthe graph. By using the Semantic Web, the graph becomesmachine-understandable and thus more easily navigated, imported by, searched, and integrated by other applications.

For example, let’s say that social network Application A comes alongand wants to use the dataset of social network Application B. App Asees the graph of nodes and links in B, and it sees something called a”has team” link connecting various nodes in the graph together. Whatdoes that mean? What kinds of things can or cannot be connected withthis link? What can be inferred if things are connected this way?

The meaning of “has team” is ambiguous to App A because it’s notdefined anywhere that the software can see. The only way App A can useApp B’s data correctly is if the programmer of App A speaks to theprogrammer of App B (or reads something they wrote such asdocumentation of some sort) that defines what they meant by the “hasteam” link.