@Article{	  valiente:sigart:1992,
  author	= {Gabriel Valiente},
  journal	= {ACM SIGART Bulletin},
  number	= {1},
  pages		= {20--24},
  title		= {Using Layered Support Graphs for Verifying External
		  Adequacy in Rule-Based Expert Systems},
  volume	= {3},
  year		= {1992},
  abstract	= {The problem of verifying external adequacy in expert
		  systems is addressed in this paper. External adequacy is
		  defined in terms of a formal specification of question
		  relevance, that expresses natural data dependencies among
		  the external facts used in the ontology of the domain of
		  expertise. A method is presented for verifying the expert
		  system, at any stage of development, against the formal
		  specification. The method is based on transforming the
		  knowledge base plus inference engine into a partially
		  ordered set of <EM>support graphs</EM>. The complex problem
		  of verifying the external adequacy of expert systems is
		  then translated into a simpler path-finding problem in
		  support graphs.}
}