INTRODUCTION TO THIS TUTORIAL

Flex is a very powerful and versatile expert systems toolkit. In contrast to simple
expert system shells, Flex offers an open-ended knowledge-based solution to business
problems. Flex is implemented in Prolog, a high-level rules-based language, and has
unlimited access to the power of that underlying technology. Flex also has access to
whatever the Prolog has access to, and in the case of LPA Prolog for Windows, that
includes other applications and processes using various industry standards such as
DLLs, DDE, OLE, ODBC and much, much more.

Flex employs a ‘Natural Language’ style approach to defining knowledge through
the provision of a dedicated Knowledge Specification Language, KSL. As with many
quasi-NL systems, this can lull developers into a false sense of expectation where
rules which look as though they should compile and behave in a certain way, don’t.
Then starts the painful process of debugging and tracing. Two similar looking KSL
statements can map on to totally different underlying structures and behave very
differently.

Flex provides an interactive question and answer mechanism, which can be
configured and extended by the developer without limit. Again, the underlying Prolog
offers various high-level features for extending the User Interface.

Flex stores data within a frame hierarchy with multiple inheritance.

Flex provides a myriad of inferencing technologies, including both brittle and
fuzzy rules, and both forward and backward chaining. Forward and backward
chaining can be interleaved, so getting the best of both worlds. Flint provides the basis
for the uncertainty handling features, and supports Bayesian Updating, Certainty
factors and Fuzzy Logic.

A principal aim of this tutorial is to start you off on the right foot, and help you get
your syntax right first time, and help you start appreciate the potential of Flex.