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# GoalVariable Option (for backward chaining)

When the inference method is set to Backward, use this statement to identify the variable for which the inference engine is to solve.

The GoalVariable statement, when required, must appear immediately after the Variables(...) section of the ruleset.

        RuleSet <nameOfRuleSet> (

          <Processing Options Statement>*      // Zero or more statements

     variables {
       <Variable Declaration Statement>+  // One or more statements

     }

      void main() using Backward(goalVariable=<variableName>) {

      }

          .
          .
          .

    }

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- GoalVariable

### GoalVariable

Specifies the variable for which the backward chaining inference engine is to solve. GoalVariable is a required statement when using Backward is specified. For other inference methods, the statement must not be used.

Syntax

       void main() using Backward(goalVariable=<variableName>) {

       }

Parameters

<variableName>
  Is an identifier that names a previously defined variable.

Example

     ruleset <nameOfRuleSet> {

       InferenceMethod(Backward)

      variables { Diagnosis string("unknown");

       ...

      }

      void main() using Backward(goalVariable=Diagnosis) {
                              // The backward chaining inference engine
                                 //   tries to determine the diagnosis.

      .
          .
          .

      }

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Last modified: Thu Mar 29 14:50:28 CST 2001