Comparing Formal Specification Languages

This paper presents a comparison between eight specification languages discussed during the Workshop on Formal Specification Techniques for Complex Reasoning Systems held in Vienna during the ECAI'92 conference. The languages as discussed here possess many important common characteristics, but also differ substantially. The analysis discussed here departs from looking at the purposes of the presented languages. The comparison focuses on the way of dealing with heuristic knowledge in the specification of the common example task. Some differences between the languages are discussed: \begin{itemize} \item expressive power; \item the way of specifying control knowledge; \item layering of the system architecture. \end{itemize} We identify where already a certain consensus can be found; points are discussed that are in common for most of the languages: \begin{itemize} \item modularity; \item local declarativeness; \item multi-level view on a specification; \item distinct specification of static and dynamic aspects; \item separation of generic and domain-specific parts of a specification; \item object-meta distinctions in specifications; \item the level of specification. \end{itemize} Moreover, the major open problems are presented