Analytico-synthetic classifications did provide an
appropriate and useful approach to the problems
related to more clearly defining the relations between
concepts in a given context. Jason Farradane’s
Relational Indexing is probably the most expressive
of all the relational indexing systems in terms of
its ability to explicitly and clearly specify relations
between concepts. However, recognising that application
of traditional KOS in the digital environment is an
expensive proposition, the focus in research has
been on further refining and extending Boolean
‘AND’ and ‘OR’, and on improving the quality of
keyword identification and extraction. Proximity
operators and Field-specific searches have been
introduced to further refine the ‘AND’ operator and
Truncation for string searching. These to a certain
extent helped in restricting/widening (depending on
the need) the class of documents to be retrieved.
There were also several experiments aimed at
implementing processes that helped refine the
definition of keywords: