Minimisation of incompletely specified sequential machines: the 'really' excluded compatibility classes

The known methods for the minimisation of incompletely specified sequential machines do not take into consideration the number of unspecified entries in the flow-table of the minimal machine. In this note, we show that the prime compatibility classes (following the definition of Grasselli and Luccio) do not allow such an additional condition. Here we give a more complete definition of the excluded compatibility classes and a method for deriving them.