Rule interpreters in ELEKTRA

Describes a number of rule interpreters, each of which is represented as a set of production rules which can be executed as an ordinary ruleset in the ELEKTRA system. The interpreters override the default behaviour of the ELEKTRA interpreter: the default behaviour is forward‐chaining; shows how to implement backward‐chaining and content‐directed control. Some of the interpreters described are capable of interpreting themselves. Shows that ELEKTRA is powerful enough to support a wide variety of different interpreters without requiring any changes to its code. None of the interpreters requires additional system code in order to work: ELEKTRA provides all of the facilities used by the rulesets as part of its standard library. Provides additional evidence of the enormous power of reflective systems and of ELEKTRA in particular.