In this paper we will show that certain networks called 'inhibition nors' m
ay be regarded as cognitive agents drawing nonmonotonic inferences. It will
be proven that the system CL (introduced by KLM in [Artificial Intelligenc
e 44 (1990) 186-189]) of nonmonotonic logic is both sound and complete with
respect to the inferences drawn by finite hierarchical inhibition nets. Th
e latter class of inhibition nets is shown to correspond to the class of fi
nite, normal, hierarchical logic programs concerning dynamics, and also to
the class of binary, layered, input-driven artificial neural networks. (C)
2001 Elsevier Science B.V. All rights reserved.