Difference between revisions of "Semantics"

Revision as of 15:44, 25 April 2022

Full Title or Meme

When an Entity can determine the "significance" of words in sentences.^[1]

Context

• Based on the obsolete idea that all of language can be divided into Syntax (order) and Semantics (meaning).
• Some data elements have meaning that is independent of the places where they are used. These cases are handled well with a Data Dictionary. See that wiki page for non-context-dependent semantics.
• For data elements that are context-dependent, the meaning cannot be known without reference to the context. These cases need a richer model.

Semantic Models

• Semantics in data processing goes back to the 1980's when EDI and XML structures were being defined.
  • In the case of EDI all semantics were context-dependent. The concept context definition was introduced by Tom Jones at a meeting at MIT where a data type was defined to say that the following data values had meaning only in that document at that location.
  • In the case of XML, the contexts were established at the top of the document and the specific context tag was prepended to the element name. So if the context name was "x", an element of that context would appear as x:tag.
• Data Dictionaries appeared in the databases with the EAR or Entity Attribute Relational models used with languages like SQL. In that case the context was the table where the data meaning was described.
• The Semantic Web can be dated to a paper by Tim Berners-Lee's paper^[2] in 2001 and the publication of the OWL language in 2004.^[3] which spawned an bewildering collection of data dictionaries which are ostentatiously called Ontologies when what they are is just what their employers imagine the reality should be.
• The result is not a collection of words that users of computer understand, but what the advertisers want them to see.
• An alternate source of Ontologies is the result of an Artificial Intelligence has determine what terms the training set is using. That might be closer to what the users that created the training set might want to know.^[4] For an example see WikiData " a free and open knowledge base that can be read and edited by both humans and machines."

References

1. ↑ Webster's Third International Dictionary, Etymology of Semantics
2. ↑ Berners-Lee +2, The Semantic Web Scientific American (2001-05-17) https://www.scientificamerican.com/article/the-semantic-web/
3. ↑ W3C, OWL Web Ontology Language Overview (2004-02-10) http://www.w3.org/TR/owl-features/
4. ↑ Pascal Hitzler, A Review of the Semantic Web Field CACM 64 No 2 pp. 76ff