**8. References**

126 Real-Time Systems, Architecture, Scheduling, and Application

Fig. 20. The activity diagram presenting the construction of the graph of possible scenarios


**6** 

*Iran* 

**Construction of Real-Time** 

*1University of Kashan, Kashan,* 

**Oracle Using Timed Automata**

Seyed Morteza Babamir1 and Mehdi Borhani Dehkordi2

Verification of real time software is facing two problems: (1) how we should manage to produce verification rules and (2) how we should apply the rules to specify the problem. In this chapter we provide a method by which we get down to these two problems. In the first step, we specify real time software using *Timed Automata* and then we state it in RTL, real time logic, propositions. Timed Automata address modeling systems in time (Alure & Dill, 1996). In the second step, we obtain the safety constraints from *reachability graph* of Timed Automata of the problem specification and after that we state it in real time logic propositions. These propositions showing safety constraints are used for verification of the propositions, i.e. the results of the specification obtained in the first step. To show the effectiveness of our method,

Software verification is an important process in constructing software and a main factor for obtaining safety from the quality of software. For verification of software we should deal with its verification against the expected behavior. The expected behavior is safe characteristics or prepositions that the software must always agree with. For this purpose, there are three main approaches: (1) static verification, (2) software testing and (3) run-time verification. Meanwhile one of the important and key approaches, essentially used for mission and safety critical systems, is the run-time verification; the existence of the problems in the first and second approaches is the reason of using run-time verification. For example, we can indicate the disability of the first method in proving the complicated and large specifications. Another instance is rapidly increasing the number of states (called state

Because Timed Automata are methods based on time and event, they are suitable for describing the behavior of real time systems and because Timed Automata are visual methods, their understanding is easy. But they have limitations for specification of some statuses and also they cannot specify some conditions very well. Therefore, we need especial methods for analysis and verification of Timed Automata behavior that increase safety in

There are different ways to verification of Timed Automata behavior. One of these ways is using *reachability graph*; however an especial method should be chosen to cover the

we set forth it for the RCC (Rail Road Crossing Control) real time system.

explosion) in the *model checking* method, which is a static verification one.

these systems and decrease the amount of the faults.

**1. Introduction**

*2University of Science and Applied Shar-e-Kord, Shahr-e-Kord,* 


URL: http//www.elsevier.nl/locate/entcs/volume39.html 13 pages

