Minimal dimension inverses of linear sequential circuits

The concept of an elementary null sequence of a linear sequential circuit is introduced. Its properties are used to formulate a necessary and sufficient condition for the invertibility of a linear sequential circuit and to determine the minimal dimension of an
L
-delay inverse. A general method is given for constructing a minimal dimension inverse which utilizes the state description of the original linear sequential circuit and which applies whenever
L = 0
or whenever the next-state map of the linear sequential circuit (LSC) is onto.