Page 248 - DCAP208_Management Support Systems

Unit 14: Knowledge-based Decision Support

The Knowledge Base Notes

The knowledge base is the store in which the knowledge in the particular domain is kept.
The knowledge base stores information about the subject domain. However, this goes further
than a passive collection of records in a database. Rather it contains symbolic representations of
experts’ knowledge, including definitions of domain terms, interconnections of component
entities, and cause-effect relationships between these components. The knowledge in the
knowledge based is expressed as a collection of fact and rule. Each fact expresses relationship
between two or more object in the problem domain and can be expressed in term of predicates
IF condition THEN conclusion where the condition or conclusion are fact or sets of fact connected
by the logical connectives NOT, AND, OR.

!
Caution We need to create a variable name list to help to deal with long clumsy name and
to help writing the rule.
Variable Name Meaning
Interest rise interest rate rise
Interest fall interest rate fall

Stock rise market stock fall
Stock fall market stock fall
Naira rise exchange rate rise

Naira fall exchange rate fall
Inflation rise cost of market product rise
Fedmont add increment of federal reserve money in circulation
Tax add taxation on market product increase
Tax fall taxation on market product decrease

Using the above variable name, the following set of rule can then be constructed.
Rule 1: IF interest rise THEN stock fall
Rule 2: IF interest fall THEN stock rise

Rule 3: IF naira fall THEN interest fall
Rule 4: IF naira rise THEN interest rise
Rule 5 IF stock fall THEN inflation rise
Rule 6 IF fedmont add AND tax fall THEN naira rise
IF THEN rules are treated very differently from similar constructs in a natural programming
language.
While natural programming languages treats IF THEN construct as part of a sequence of
instructions, to be considered in order, the rule based system treats each rule as an independent
chunk of knowledge, to be invoked when needed under the control of the interpreter. The rules
are more like implication in logic (e.g. naira rise → interest rise).

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