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ontology disambiguation. Technically the same as schema, different connotations #2

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ontology disambiguation. Technically the same as schema, different connotations #2

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Update ontology.md
kilojoules Dec 15, 2022
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thclark Dec 16, 2022
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10 changes: 9 additions & 1 deletion terms/ontology.md
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Expand Up @@ -37,11 +37,19 @@ Example: OWL Ontology Language is based on Description Logics, OWL Ontology cons

</details>

{% hint style="warning" %}
**Disambiguation**
An ontology is technically equivalent to a schema. Both are formal specifications of some conceptualisation or abstract world model.

From its usage in the Semantic Web community and the broader knowledge-based systems community, the term 'schema' is used to refer to simple conceptualisations, as might be written using less expressive knowledge representation languages such as RDF Schema (so making explicit the relationship between ontologies and database schemas). Conversely, the term 'ontology' is taken to describe more complex models, written in more expressive languages (OWL, DAML+OIL, Ontolingua, KIF, etc).

There is a school of thought that considers ontologies to contain rule-based knowledge in addition to a relational characterisation, but this is far less prevalent in the SW community than elsewhere.
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You say in a comment this is taken from https://www.w3.org/wiki/SchemaVsOntology but haven't referred to that anywhere - please include a hyperlink to this source reference.

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I'm not sure what the best way to link this is. Should I put all the text in quotes?

{% endhint %}

{% hint style="info" %} *Note
{% hint style="info" %} **Note**

It can be useful to classify ontologies as being designed to deal with an open world or closed world. In other words, whether or not the content of the ontology is modular.

Formally, the open and closed world ontologies can be described as "assertion box" \[[Reiter, 1980](https://dl.acm.org/doi/pdf/10.1145/322186.322189)] \[[Brodie, 2012](https://link.springer.com/book/10.1007/978-1-4612-5196-5) and "terminology box" \[[Lutz, 2012](http://www.informatik.uni-bremen.de/tdki/research/papers/2012/LutSeyWo-DL12.pdf). The assertion box is essentially a database, which expresses member assertions. The terminology box is designed for modular schema, specifying concepts and relations. Using this encoded knowledge many diverse databases can be queried using the same semantics. It is possible to represent subclass relationships ($\subseteq$) and equivalence ($\equiv$), conjunction ($\cap$), disjunction ($\cup$), negation ($\neg$), property restrictions ($\forall$, $\exists$), tautology ($\top$), and contradiction ($\bot$).

{% endhint %}