EXSYS Professional Developer Interface

Increment/Decrement System
This system is intuitive and easy to use. Points are added
to or subtracted from the total score for a choice. A rule
can add or subtract as much as 100 points from the total
for a choice. At the end, the total value for a choice is
displayed. This system differentiates among possible
solutions that would provide similar or identical scores
using other systems.
Custom Formula System
This is by far the most complex of the systems. It can be
used when a problem cannot be solved by one of the other
systems. In this system, you can write your own formulas
for the combination of confidence values. This provides
enormous flexibility. One method of combining
confidence values can be used in one part of an expert
system and another method in the rest of the system.
Also, in addition to the confidence associated with a
choice, this system allows the EXSYS Professional data to
have associated confidence values. The confidence values
associated with the data can be asked of the user, set to
default values, or derived from rules. The confidence of a
choice can take into account the confidence of data
relevant to that choice. This flexibility allows very
complex systems of confidence factors to be implemented.
Fuzzy Logic
Fuzzy logic is a very powerful technique that enables you
to build expert systems that more closely reflect the real
world. In the Fuzzy Logic confidence mode, fuzzy
membership functions are defined which assign
confidence to various qualifier values based on the value
of a variable. These confidence values are propagated
through the rules to the confidence assigned to choices or
other qualifiers. Specific values can be defuzzified out of
the results to have the system give precise
recommendations.
EXSYS RuleBook and EXSYS RuleBook PLUS support
the YES/NO, 0-10 and Increment / Decrement modes.
EXSYS FRAMES
FRAMES provide a way to handle more complex data.
Frames allow multiple columns and complex search
criteria with Boolean operators. The data in a frame can
be read or updated by the expert system. Frames also
provide inheritance which allows a hierarchical set of
frames to be created with data in “parent” frames available
to lower level frames. The use of frames provides a way
for EXSYS expert systems to handle data that is portable
across all platforms. Frame data is accessed by a FRAME
command in EXSYS that can be used in rules, associated
with data items, or called from the Command Language or
report generator.
EXSYS BLACKBOARDS
Blackboards provide a flexible means for EXSYS expert
systems, and other applications, to store and retrieve data.
6 • THE EXSYS DEVELOPER OVERVIEW
The data is typically shared between/among multiple
expert systems and other programs in a knowledge based
application. A set of EXSYS blackboard commands
enable you to read or write data to the blackboard and to
maintain the blackboard. The blackboard files are simply
text files and can be easily read or created by other
programs.
PARAMETER REPLACEMENT
Data dynamically set by the expert system can be inserted
in any text string, formula or command. In EXSYS,
variables are designated by including them in square
brackets, [X]. For example, [X] would be the variable X.
If a string contains the variable in double square brackets,
the value/text for the variable will be inserted into the
string before the string or command is executed.
Similarly, qualifier text and values can also be embedded
in a text string.
This simple feature enables you to write dynamic
commands that are modified and set by the system and
user input. Notes can easily contain the actual data
provided by the end user, or obtained from an external
program. Complex meta-rules can be developed to step
through arrays of data. Self-modifying command files can
be generated. The use of parameter replacement allows
the building of very complex systems.
A simple example of parameter replacement is the
development of user interfaces that reflect data input. We
might have an EXSYS Professional variable [NAME] that is
obtained from the user or a database which contains the name
of the user. We could make the prompt to ask a question:
[[NAME]], please tell me...
EXSYS Professional will automatically replace [[NAME]]
with the actual user name at the start of the prompt.
This is a very simple use of parameter replacement, but it
displays how easily such customization can be added in
EXSYS. In other expert system shells, embedding the
name would be difficult or impossible.
The EXSYS RuleBook
Developer Interface
EXSYS RuleBook introduces a new approach to building
expert systems rapidly. A combination of a tree structured
representation of the knowledge and a sophisticated
system for detecting errors in the developer’s logic has
produced a tool that can be learned in a very short time.
Systems developed with RuleBook can serve as stand
alone applications or be enhanced through upward
compatibility with the EXSYS Professional Expert System
Development tool and EXSYS Linkable Object Modules.
EXSYS RuleBook PLUS provides a command language
that can be used to control the execution of the expert
system and interface to other programs and data sources.