Database Reference
In-Depth Information
so there was no clue it had ever been there. We crossed the wooden bridge over the
railway cutting and turned downhill past the Scots pines on Black Down, following
the path to the spring. It was still there and flowing well enough, but fenced off by the
railway company and inaccessible. (Deakin, 2008)
Descriptions can be extremely rich in terms of information content but difficult
to access from a machine perspective due to the use of natural language. As a result,
such descriptions are rarely seen as GI, but we should not ignore this type of content
as it can be either text mined for information that can then be formally represented
or stored as is for consumption by people.
3.3.3.2 Classification
Classification is the means by which we categorize the objects around us. It can be
viewed as a distillation of a textual description of the object being classified, encap-
sulating in a word or short phrase an aspect of the nature of something. Individual
categories do not exist in isolation but are components of classification systems, typi-
cally taxonomies: hierarchical assemblies of categories adhering to some system of
classification, or simple lists of categories, often known as “controlled vocabularies.”
Traditionally, classification schemes were the remit of the professional, carefully con-
structed and applied by the professional for the professional. Where the public was
exposed to them, it was based on viewing the classifications that had been applied.
Web 2.0 has changed that to an extent, opening up the classification of the world to
the hoi polloi
(although in truth there has always existed a tradition of classification
systems being constructed by the expert amateur). This has resulted in more informal
classifications arising, often termed
folksonomies
. A folksonomy is an emergent sys-
tem of classification that arises when individuals create categories (or tags as they are
often known by the contributors). The folksonomy is the resultant collection of tags,
which may be hierarchically structured (but more often not), representing some form
of consensus. Tagging is also used even more informally to classify anything from
photographs like in Flickr, to destinations, as in Foursquare (although here there is
an attempt to develop a hierarchy). In some cases, there is a high degree of agreement
regarding the meaning of the classes or tags; in other cases, the systems are quite
ambiguous, with different people using different tags to mean the same thing or the
same tags to mean different things. Professional systems and some folksonomies rep-
resent single worldviews that throw up limitations of expression, although they are
generally less ambiguous. Other folksonomies are effectively a mosaic representing
the views of individual contributors and can therefore be very ambiguous. In either
case (professional and amateur), ambiguity can occur and can only be resolved if
the semantics of the individual classes are well defined and the classification system
described. This is often not the case, or a classification system has only been incom-
pletely applied, leading to the possibility of misinterpretation.
Another form of classification system, introduced in Chapter 2, is ontology.
Ontologies can help to overcome some of the problems of ambiguity by more formally
defining the categories and their relationships to other categories. Ontologies form
an important component of the Semantic Web, and this topic therefore deals with
them in great detail.
