An evaluation of production rules
very natural and easy to use (cognitively adequate)
very good degree of modifiability and extensibility
good efficiency of the KA process
declarative ( global control is determined by the interpreter), but less than logic
computable in linear time
possibly inefficient (90% of the time spent in matching)
not adequate for IS-A hierarchies
computation not always transparent
not very expressive: too uniform, too little structuring
domain and meta-knowledge intermixed
programming with abstractions can make the rule base very unreadable
usually do not support backtracking, with gain in efficiency, but with possibly severe negative effects of the 'destructive' modifications of the working memory