• Journal of applied mathematics & informatics
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• v.16 no.1_2
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• pp.585-593
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• 2004

In this paper we shall discuss the minimal, maximal and primary subautomata. Also the concepts of the totally reachable state and source will be introduced. It is an interesting part that mX＊ is minimal iff the source S(m) is maximal. We shall point out that the characterization of primary subautomaton comes from the properties associated with the sources S(m)'s.