In this paper, we consider the language over an alphabet T generated by a given Petri net with a positive initial marking, called a CPN language. This language becomes a prefix code over T. We are interested in CPN languages which are maximal prefix codes, called mCPN languages over T. We will investigate various properties of mCPN languages. Moreover, we will prove that a CPN language is a context-sensitive language in two different ways.
This research was supported by Grant-in-Aid for Science Research 10440034, Japan Society for the Promotion of Science