Formalizing Anaesthesia: a case study in formal specification Rix Groenboom 1 , Erik Saaman 1 , Ernest Rotterdam 2 , and Gerard Renardel de Lavalette 1 1 Research Institute for Mathematics and Computing Science, University of Groningen, P.O. Box 800, NL 9700 AV Groningen, the Netherlands. E-mail: rix,erik,grl @cs.rug.nl 2 University Hospital Groningen, Department of Medical Information Sciences, P.O. Box 30001, NL 9700 RB Groningen, the Netherlands. E-mail: ernest@fwi.uva.nl Abstract. We report on the formalization of knowledge for a support system in the field of anaesthesiology. It is a case study in the use of the formal specification method we are developing. The method consists of guidelines (using concepts from object-oriented design methods), language (AFSL, Almost Formal Specific- ation Language) and tools (type-checker, graphical representation of signatures). Keywords: Case study, Development process, Linking formal and informal methods, Medical systems, Object-orientation. 1 Introduction This paper reports on the project FAN (Formalization of ANaesthesia) which aims at formal specification of the domain knowledge that is needed to construct support systems for anaesthesiology. The specification is written in the formal specification language AFSL [26, 27], with modularization, parameterization, and sub-typing. The support systems to be based on FAN include diagnosis and monitoring systems. This case study is part of a larger research effort concerning the use of formal specification languages (the Formal System Analysis-project). The FSA-project uses several cases to develop a method (consisting of guidelines, a language and tools) that is suited to formalize so-called open (i.e. ill-structured) knowledge domains. We will not compare several methods and languages, since we have only applied one method for our formalization. 1.1 Overview of paper First, in section 2, we introduce our view on formalizing informal knowledge domains, in comparison with related work in this area. In section 3, we outline the problem: support of anaesthesia. We continue in section 4 by briefly explaining the language and method that are used for the FAN-project. Then we present the formal specification in section 5. Section 6 mentions the trajectory of the FAN-project including some of the design decisions. In the final section we draw some conclusions.