Resource Description Format

RDF

The RDF represents facts and information as a network of sorts. Each object has some connection with other object, and each connection is written down as a triple.

(subject, predicate, object) is the format of RDF. One example of this is (New_Delhi, capital_of, India)

Models can have attributes and relationships with other objects, but all these connections are modelled as triples.

SPARQL

SPARQL is a language used to query RDF template data. A SPARQL query looks like

SELECT ?name
WHERE {
    ?cid title "Introduction to Computer Science"
    ?sid course ?cid
    ?id takes ?sid
    ?id name ?name
}

It also supports aggregation, optional joins, subqueries, and more. It offers transitive closure on paths as well.

n-ary Relationships

While a single RDF triple represents a triple, we can use it to represent more. One option is to create a connector node with binary relationships to erlevant nodes.

(Barrack Obama, president_of, USA, from, 2008-2016) can be broken down into

(e1, represents, Barrack Obama) (e1, president_of, USA) (e1, president_between, 2008-2016)

Or it can be broken down as (Barrack Obama, president_of, USA, c1) (c1, president_between, 2008-2016)

Usage

RDF is frequently used to represent interconnected knowledge bases, like DBPedia, Yago, Freebase, or WikiData. Linked open data project aims to connect different knowledge graphs.