Posts Tagged ‘Open World’

Introduction to: Open World Assumption vs Closed World Assumption

Nametag: Hello, my name is O.W.A.If you are learning about the Semantic Web, one of the things you will hear is that the Semantic Web assumes the Open World. In this post, I will clarify the distinction between the Open World Assumption and the Closed World Assumption.

The Closed World Assumption (CWA) is the assumption that what is not known to be true must be false.

The Open World Assumption (OWA) is the opposite. In other words, it is the assumption that what is not known to be true is simply unknown.

Consider the following statement: “Juan is a citizen of the USA.” Now, what if we were to ask “Is Juan a citizen of Colombia?” Under a CWA, the answer is no. Under the OWA, it is I don’t know.

When do CWA and OWA apply?

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Introduction to: Ontologies

Hello my name is ontologyIn my most recent post, I introduced RDF as a flexible and schema-less data model. However, some of you may think then that using RDF data is going to be a complete mess. In some cases, that may be true; and it’s fine! There are use cases in which all you want is messy data. What if you want to do more interesting stuff with your RDF data like infer new knowledge? This is where ontologies come in.

What is an Ontology?

Let me scare you for a minute. The computer science definition of ontology is:

a formal and explicit specification of a shared conceptualization


Let’s break this down and get our hands dirty. Read more