Abstract
One of the key problems in medical knowledge representation is that we usually have no idea about the largeness of the knowledge to be represented. Underestimation of this largeness may occur frequently. Considering this situation, the authors have applied a method of measuring or estimating the largeness of a certain medical knowledge area modelled in a theoretical information space. The method is tested on two sets of terms, the OMED terminology of digestive endoscopy and on the second and third version of the SNOMED nomenclature. The assessment of largeness of a knowledge area does not seem possible by a single measure. The ‘volume’, ‘density’ and ‘complexity’ must be addressed separately. In the present study different medical knowledge-representation systems are compared according to their volume. Possible ways to estimate their complexity and density are mentioned.