Lexing and Parsing

Lexing is the process of dividing an input stream into meaningful units, or tokens, which are then processed. Parsing refers to discovering semantic meaning out of a series of tokens according to the rules of a grammar.

RDF versus RDB-shema

Fixed RDB shema :

Image taken from ontotext

The same using RDF :

Image taken from ontotext

Image taken from ontotext

Semantic Web Architecture

Some definitions about languages

A language consists of a structure definition (called abstract syntax or meta model), a definition of the notation (also called concrete syntax) and semantics. In semantics we distinguish between the static semantics (constraints, typesystem) and the operational semantics (what something means as it is executed).