An Approach to Medical Diagnosis Based on Conceptual Structures

Abstract

The power of an experienced medical diaanostician seens to us to arise from a knowlada• oraantzat ion whosE: very structure helps keep the combinatorial growth of processing under control. Thi• •tructure mirrora the deep conceptual structure of the field. We propose a knowledge representation achPme called concaptual ~tru~tures, which ~rganj,~ea _ knowled&e J n the form of product ion rule s or nore complex procedures l.n Ruch a way that they are acceased and uaed as needed. This structure is doninantly hierarchical, the successors of a conceptual node stand in& for aubconcepta which refine that concept. Associated with each concept is a aet of procedures (experts) which attempt to apply the relevant knowledge to the case at hand; this might include turninc over control tr aelected aubconcepts for more detn1lec' anAlysis. Thus, ahstractly, the crnce!ltuAl structure organizes th• invocation of procedures available to the diar,nosticinn. ThP calling· C'f " specinliAt by 8 physician is akin, we think, tC' control transfer to a subconcept in the Cc>f.nitive structure of a diRr,nosticisn durin• problem aolvinr.; the difference is in thP. level of det111l of the corritive m:~p. In thiR pAper • so!"e principles auvernint the deRi~;n of conceptual structures are presPntPc. l?e :~pply the i ~en11 to the dct<ign of t:IJX, a system to perform di~tgnoses in a syndrone called CholeBtasis 1 anc~ rliscu,;s the perfornAnce of the system.