Jürgen Ruf

Symbolic model checking for a discrete clocked temporal logic with intervals

In this paper we present a new model checking algorithm for interval based timed structures and temporal logic formulas. Besides the treatment of time intervals the new algorithm leads to a significant performance gain compared to previous approaches.

Modleing and Checking Networks of Communicating Real-Time Process

In this paper we present a new modeling formalism that is well suited for modeling real-time systems in different application areas and on various levels of abstraction. These I/O-interval structures extend interval structures by a new communication method, where input sensitive transitions are introduced. The transitions can be labeled time intervals as well as with communication variables. For interval structures, efficient model checking techniques based on MTBDDs exist. Thus, after composing networks of I/O-interval structures, efficient model checking of interval structures is applicable. The usefulness of the new approach is demonstrated by various real-world case studies, including experimental results.

Using MTBDDs for discrete timed symbolic model checking

The verification of timing properties is an important task in the validation process of embedded and real time systems. Temporal logic model checking is one of the most successful techniques as it allows the complete automation of the verification. In this paper, we present a new approach to symbolic QCTL (Quantitative CTL) model checking. In contrast to previous approaches we use an intuitive QCTL semantics, provide an efficient model representation and the new algorithms require less iteration steps compared to translating the QCTL problem into CTL and using standard CTL model checking techniques. The new model checking algorithm is based on a MTBDD representation. Some experimental results show the efficiency of the new approach.

Using MTBDDs for Compostion and Model Checking of Real-Time Systems

In this paper we show that multi-terminal BDDs (MTBDDs) are well suited to represent and manipulate interval based timed transition systems. For many timed verification tasks efficient MTBDD-based algorithms are presented. This comprises the composition of timed structures based on symbolic techniques, heuristics for state variable minimization, and a symbolic model checking algorithm. Experimental results show that in many cases our approach outperforms standard unit-delay approaches and corresponding timed automata models.

A New Algorithm for Discrete Timed Symbolic Model Checking

When extending CTL with constructs for quantitative reasoning on time, either the linear algorithm complexity of standard model checking gets lost, efficient ROBDD techniques are no more applicable or the semantics becomes counter intuitive.