Models for rule interpreters

There are several ways in which selection and execution of rules can be implemented for the forward chaining. These are:

• linear execution - After finding and executing a single rule, the next rules are examined and executed in turn. After reaching the last rule the system goes again to (backtracks) the beginning.
• hierarchical interpretation - From the beginning to the first executed rule (one with satisfied preconditions), then the system goes to the beginning and repeats the cycle.
• linear interpretation with rule switching - This is the hierarchical interpretation, but when the system reaches the executed rule, it jumps to the rule or rules indicated by the recently executed one.
• linear examination with context switching - After some rule is executed, the current state of the system is evaluated (a context), then execution of rules can be switched to a different set of rules appropriate for this context.