A formalism is elaboration tolerant to the extent that it is convenient to modify a set of facts expressed in the formalism to take into account new phenomena. Representations of information in natural language have good elaboration tolerance when used with human background knowledge. Human-level AI will require it. We use the missionaries and cannibals problem and about 20 variants as our \emph{Drosophila} in studying elaboration tolerance.
There are .html, .dvi, .pdf and Postscript versions of this article.
The present article has an inadequate version of the section that should be its centerpiece - namely the situation calculus formalizations of missionaries and cannibals. This is partly because I think a substantially extended version of situation calculus is required for elaboration tolerance. However, the section expresses my point of view well enough.
The paper was given at Common Sense 98, 1998 Jan 7-9 in London. However, as of 1998 April, the paper was under further development, so the present version is not the same as that of the conference.
I welcome comments, and you can send them by clicking on jmc@cs.stanford.edu