
\chapter{Introduction}

% semantic web
%What is the semantic Web? Can I think clearly about this? Do I want to? 
% semantic web rule languages
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%It seems like things from other chapters may belong here. 
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%Computer process data. The more data that is in a form that can be processed, the better they can do. 
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%I'm not making a coherent, full, statement here.
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%I need some history here. People started storing ever increasing amounts of data in computers. Vast databases were built. Hierarchical, and later relational databases were used. %(@@citations needed)

The great power of computers lies in their generality. A single computer can be programmed to do anything, and to process any kind of data. This generality extends to programs and data: The more programs that can process given data, the more useful it is. Also, the more data that a program can process, the more useful it is. 

Any data format must be modeled to some level. If this model is too general, it means nothing. If it is too specific, one cannot use it to represent the data one wants. Getting the right balance to get this right is an open problem.

As one extreme, we have the byte-stream representation of a data base. This can represent anything. However, there is no semantics whatsoever associated with the format. Everything is in level above it. Therefore, we can transfer the files in this format and store on the disk, as indeed we do, for data integration this is not useful.

A higher level model of data is the relational database. There are an almost unlimited number of ways of mapping a particular dataset to a set of relations. Some of them are little better than the byte stream. Others model the data in a more extensible way. 

The Semantic Web is an attempt to allow for just that. By using Uniform Resource Identifiers \cite{URI} (or Internationalized Resouce Identifiers) to represent things, it is possible to merge different data source in sane ways. Then, with a representation of a set of triples, it is possible to model arbitrary tuples. Any data can be represented in this way. Modeled well in RDF, the data may be usable for more than just the original intention. The W3C Semantic Web Best Practices Working Group\cite{bestpractices} publishes some guides on how to model data well. 


Once the data is in useful formats, the question becomes what can be inferred from the data, and how to verify the inferences. This is building on decades of work in logic and inference. 

In order to do this, we need to define logics and data models that scale to the Web. Notation3 is an attempt to supply both. It is an extension of RDF to include the ability to represent many more things.
% motivation 

One of the things Notation3 can represent is rules. Rules, saying that one thing implies another, have been created in many forms over the decades. Several algorithms have been devised for processing these rules. It bears investigation what of these would work well for the Semantic Web. 
