ACQUIRING QUALITATIVE KNOWLEDGE ABOUT COMPLEX AGROECOSYSTEMS .2. FORMAT REPRESENTATION

In a companion paper (Sinclair and Walker (1998) Agricultural Systems 56, 341-363) a simple and intuitive method for representing qualitativ e knowledge held by farmers and researchers about complex agroecosyste ms, such as agroforestry, was presented This involved generating sets of statements in natural language. The present paper develops the meth odology further through the introduction of a formal method of represe ntation. This involves employing a restricted syntax that facilitates the use of automated reasoning procedures and the development of diagr ammatic techniques that help users to appreciate linkages amongst inte r-related statements. The role of the resulting formal methodology in the process of knowledge acquisition is then discussed in the context of getting multiple informants, such as members of farming communities , to articulate their understanding of the ecology of their farming sy stem and then developing knowledge bases that are an explicit and repr esentative abstraction of what they knew. It is demonstrated that the iterative evaluation of the knowledge people articulate, enabled by th e process of formal representation, significantly increases the cohere nce, consistency and completeness of the knowledge bases that are gene rated over what can be achieved with less formal methods of representa tion. It is, therefore, proposed that the formal methods outlined here provide an effective means of helping researchers and development pro fessionals to develop robust, rigorous and defendable qualitative mode ls of the behaviour of complex agroecosystems. (C) 1997 Elsevier Scien ce Ltd.