 blue} {white,blue} {white,blue} {red,yellow} {red,yellow} e0: dressOrd(color,color) e1: changeJacketOrd(color) e2: changeTieOrd(color) e3: changeBothOrd(color,color) e4: undressOrd() Fig. 7.43 The FSM diagram for the dressing case The behaviour description to the right in Fig. 7.43 is an FSM diagram, since every state is a unique value of the resource model. FSM is quite feasible in this case, considering that the state space comprises only seven states. The behaviour is based on the five operations that are defined, all of class ORDER. The wife always starts and ends with the request that the husband wear the grey jacket and blue tie. Some variations in the selection process from one party to another are also recorded in the state diagram to the right. The notation e1, e2, and SO forth, abbre- viates the ASPs that are used. Assume now that we want to produce a state diagram representation of the behaviour in Fig. 7.43 that reduces the number of states. We can do that by focus- ing on one state variable as the explicit state variable. In Fig. 7.44 we have selected the variable tie to be that variable, and have drawn an EFSM diagram based on the fact that each state symbol denotes a unique tie value. Note that the FSM and the EFSM diagrams describe exactly the same behaviour. The state symbols depicted in the EFSM diagram reflect only different tie val- ues, i.e. we will only depict three state symbols. Obviously, this means that two of the three state symbols now represent sets of states (explicit states) in the state space. For example, the state {tie blue} represents all states where tie=blue, in this case three different states. 7 Concepts and Notations for Process Control Systems Modelling FSM diagram: EFSM diagram: {undressed} pre: {jacket white) post :{jacket grey} post: (jacket red} ({undressed) (tie blue} pre:{ jacket red} (grey.blue) post: {jacket grey} The explicit state {white,yellow} {tie blue) pre: {jacket grey) post: {jacket white) pre: (jacket grey} (grey.yellow) (red,blue) post: (jacket white) pr