In this paper, parsimonious covering theory is extended in such a way
that temporal knowledge can be accommodated. In addition to causally a
ssociating possible manifestations with disorders, temporal relationsh
ips about duration and the time elapsed before a manifestation comes i
nto existence can be represented by a graph. Precise definitions of th
e solution of a temporal diagnostic problem, as well as algorithms to
compute the solutions are provided. The medical suitability of the ext
ended parsimonious cover theory is studied in the domain of food-borne
disease. (C) 1997 Elsevier Science B.V.