Rules based Organizing of the Knowledge in AI

In computer science, rule-based systems are used as a way to store and manipulate knowledge to interpret information in a useful way. They are often in artificial intelligence applications and research.
In computer science, a rule-based system is a set of "if-then" statement that uses a set of assertions, to which rules on how to act upon those assertions are created.
In software development, rule-based systems can be used to create software that will provide an answer to a problem in place of a human expert.
The human mental process is internal, and it is too complex to be represented as an algorithm.However, most experts are capable of expressing their knowledge in the from of rules for problem solving.

              IF            the 'traffic light' is green
              THEN     the action is go

              IF            the 'traffic light' is red
              THEN     the action is stop

Rules as a knowledge representation technique

The term rule in AI, which is the most commonly used type of knowledge representation, can be defined as an IF-THEN structure that relates given information or facts in the IF part to some action in the THEN part.
A rule provides some description of how to solve a problem.Rules are relatively easy to create and understand.

- Any rule consists of two parts:
- the IF part, called the antecedent (premise or condition)
- and the THEN part called the consequent (conclusion or action).
            IF            <antecedent>
            THEN     <consequent>
     3. A rule can have multiple antecedents joined by the keywords AND (conjunction), OR (disjunction) or a combination of both.

             IF              <antecedent 1>      IF      <antecedent 1>
             AND         <antecedent 2>      OR    <antecedent 2>
                                       .                                          .
                                       .                                          .
                                       .                                          .
            AND           <antecedent n>      OR      <antecedent n>
             THEN        <consequent>        THEN <consequent>

The antecedent of a rule incorporates two parts: an object (linguistic object) and its value. The object and its value are linked by an operator.
The operator identifies the object and assigns the value. Operators such as is, are, is not, are not are used to assign a symbolic value to a linguistic object.
Systems can also use mathematical operators to define an object as numerical and assign it to the numerical value.

IF 'age of the customer' <18

AND ' cash withdrawal' > 1000

THEN 'signature of the parent' is required

Rules can represent relations, recommendations, directives, strategies and heuristics:

Relation

IF the 'fuel tank' is empty

THEN the car is dead

Recommendation

IF the season is autumn

AND the sky is cloudy

AND the forecast is drizzle

THEN the advice is 'take an umbrella'

Directive

IF the car is dead

AND the 'fuel tank' is empty

THEN the action is 'refuel the car'

Strategy

IF the car is dead

THEN the action is 'check the fuel tank'; step 1 is complete

IF step 1 is complete

AND the 'fuel tank' is full

THEN the action is 'check the battery'; step 2 is complete

Heuristic

IF the spill is liquid

AND the 'spill pH' < 6

AND the 'spill smell' is vinegar

THEN the 'spill material' is 'acetic acid'

There's If Then, and Then There's If Then

It is very tempting to store if-then logical relationships in procedural code, especially since procedural code has if-then statements.
In fact, not only is it tempting, it can work reasonably well up to a point.
It's the road bit that cause the trouble.
A logical relationship can be coded as a procedural if-then, but must be placed somewhere along the road of execution of the procedure it is in.
It makes a difference which rule gets placed first, and if there are branches from previous rules, and which branch a following rule is placed on.