Russell Greiner, Douglas B. Lenat
The field of AI is strewn with knowledge representation languages. The language designer typically has one particular application domain in mind: as subsequent types of applications are tried, what had originally been useful features become undesirable limitations, and the language is overhauled or scrapped. One remedy to this bleak cycle might be to construct a representational scheme whose domain is the field of representational languages itself. Toward this end, we designed and implemented RLL, a frame-based Representation Languange Language. The components of representation languages in general (such as slots and inheritance mechanisms) and of RLL itself are encoded declaratively as frames. Modifying these frames can change the semantics of RLL, by radically altering the character of the RLL environment.