next up previous
Next: Meta-rules: Structural Control Up: Control knowledge Previous: Meta-predicates in premises

Meta-rules: Deductive Control


The deductive control (see Figure 13) may affect the deductive knowledge of a module by inhibiting rules or deducing instances of the meta-predicate K. Moreover, instances of any user-defined meta-predicate can be generated. These meta-rules are responsible for the implementation of a type of meta-reasoning based on changing the object level theory in two ways: by reducing it (eliminating some rules), or by changing it (deducing instances of the meta-predicate K). Next you have a description of the meta-predicates allowed in the conclusions of this type of meta-rules. The action to be taken after a meta-rule deduces an instance of these meta-predicates is explained in Section 5.1.3.

Inhibit Rules:
This action inhibits all the rules containing the fact pathpredid in their premises. Optionally we can introduce a name of relation relation-id. Then the rules inhibited will then be those containing in its premises a fact related with pathpredid.

It inhibits all the rules belonging to the deductive tree of the fact pathpredid.

Here users are allowed to conclude any meta-predicate. Only when the meta-predicate is the predefined K an action consisting on overwriting a fact value at the object level will be undertaken in the reflection phase. The remaining instances of user-defined predicates will remain as part of the meta-level state, and will eventually be used as conditions of other meta-rules to be fired in this and in posterior activations of the meta-level component.

Josep Puyol-Gruart
Thu Oct 23 15:34:13 MET DST 1997