In this paper we continue to study the fuzzy logic system from the aspect o
f fuzzy differential equations and discuss the concept of observability. Gi
ven the rule base for the input and the output, we can determine rule base
for initial value by a formula. The significance of this result is that giv
en a deterministic system and fuzzy input and output rule base, we can dete
rmine the rule base for initial value without solving the equation. (C) 200
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