Expressing qualitative biomedical knowledge exactly using the language LESK

A language (LESK) is described which allows one to make mainly qualitative declarations of the essential terminology and facts in some technical subject. LESK is essentially first order predicate calculus, made to look like natural language. A LESK system, now partially implemented in PROLOG, allows one to enter declarations and assertions, check consistency, and deductively answer predominately generic, universally quantified questions. An extensive example is presented in which LESK is used to describe neurophysiological knowledge about the stretch reflex.