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Re: metadata and ontologies

From: Ettore RIZZA <ettorerizza@gmail.com>
Date: Wed, 25 Sep 2019 12:57:40 +0200
Message-ID: <CAGq-dooeB07rN-4U=fVGm_Gidp3xCJYXag=JUty4G8B5mOsBCQ@mail.gmail.com>
To: Alexander Garcia Castro <alexgarciac@gmail.com>
Cc: "semantic-web@w3.org" <semantic-web@w3.org>

(too) simply put, metadata is data about data. eg, when you take a picture,
the data is your digital picture, and the metadata is for example the EXIF
data of that picture.

[image: cf4cba13-d2bb-4f01-882a-d71d7dfdceed.png]

EXIF metadata respect a standard and a controlled vocabulary. For example,
the photo size is called "Dimensions", not "size" or whatever. Controlled
vocabularies are simply vocabularies (word lists) that are less rich than
natural language, which helps to limit their ambiguity. There are a
thousand ways to designate a car in the English language, but a controlled
vocabulary worthy of the name will only have one, with possibly a small
list of acceptable synonyms.

There are several types of controlled vocabularies. The simplest is the
word list, then comes the taxonomy, which is a list of words classified
hierarchically... The richest, until a few decades ago, was the thesaurus,
which is a list of words classified hierarchically with additional semantic
elements (synonyms, hyponymy, hypernymy...).  Ontology is a controlled
vocabulary that is even richer in semantics than the thesaurus.

Let us take the word "maiden name". A thesaurus may just tell you that it
is a subclass of "Name" or "Last Name", that it is synonymous with "Birth
Name", etc. An ontology will be able to stipulate that this word can only
be used when the conditions "women" and "married" are met.

In summary, metadata is data about data; it uses controlled vocabularies ;
ontologies are a subset of controlled vocabularies <- Ontologies are a part
of a subset of metadata.

That is how I understand it, and I would be happy to be corrected if I'm


Ettore Rizza

On Wed, 25 Sep 2019 at 12:14, Alexander Garcia Castro <alexgarciac@gmail.com>

> Hi all. Can someone point me to information about the difference between
> metadata and ontologies? examples?
> Thanks
> Best.
> --
> Alexander Garcia
> https://www.researchgate.net/profile/Alexander_Garcia
> http://www.usefilm.com/photographer/75943.html
> http://www.linkedin.com/in/alexgarciac

(image/png attachment: cf4cba13-d2bb-4f01-882a-d71d7dfdceed.png)

Received on Wednesday, 25 September 2019 10:58:45 UTC

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