Database Reference
In-Depth Information
4
Geographic Information
in an Open World
4.1 INTRODUCTION
The previous chapters introduced the ideas behind the Semantic Web and Linked Data.
We also introduced Geographic Information (GI), although it paints a less-coherent
picture, reflecting less consistency and greater diversity in this area. This chapter
represents an initial meeting of the two—an introduction—and it can be considered
an anchor for the rest of the topic. It sets out the general technical principles required
to represent GI on the Semantic Web, but before addressing this area, we cover two
other matters. We describe the approach that must be taken, contrasted against the
prevalent approach to mainstream GI today; and identify where the Semantic Web
can be used to best effect. There are significant, though sometimes subtle, differences
between the traditional GI handling of data and the strategies of the Semantic Web,
so it is important to clearly state how we must tackle GI on the Semantic Web. The
need to identify where the Semantic Web can be used to best effect reflects the nature
of all technologies and methodologies: They are not panaceas, they not only have
strengths but also weaknesses, and it is as important to recognize if a technology is
inappropriate as it is to know when it can be used to advantage.
If the benefits of incorporating GI into the Semantic Web are to be fully realized,
then it is not sufficient just to reimplement what we already have available in tradi-
tional systems. Instead, we need to stand back and look at how we should address
the issue afresh. It is from this perspective that we will begin, by comparing the
underlying principles that are currently associated with both the Semantic Web and
GI. Only then do we move onto the technical aspects, laying down the foundations
on which the rest of the topic is built. From the technical perspective, we also take
a route, relected in the structure of this topic, that mimics the way that we believe
the Semantic Web will grow, with an initial emphasis on the publication of data as
Linked Data before rich description is added through the development and publica-
tion of ontologies that semantically describe the data.
4.2
PRINCIPLES
4.2.1 S
emantic
W
eb
The Semantic Web is founded on what is known as the open world assumption. The
open world assumption has both a strict formal definition and a looser projection of
this definition from the abstract world of theory to the real world of the Web (if the
Web can ever be described as real). Formally, the open world assumption is that the
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