M. Oliver Möller

UPPAAL: now, next, and future

UPPAAL is a tool for modeling, simulation and verification of real-time systems, developed jointly by BRICS at Aalborg University and the Department of Computer Systems at Uppsala University. The tool is appropriate for systems that can be modeled as a collection of non-deterministic processes with finite control structure and real-valued clocks, communicating through channels or shared variables. Typical application areas include real-time controllers and communication protocols, in particular those where timing aspects are critical. This paper reports on the currently available version and summarizes developments during the last two years. We report on new directions that extends UPPAAL with cost-optimal exploration, parametric modeling, stop-watches, probablistic modeling, hierachical modeling, executable timed automata, and a hybrid automata animator. We also report on recent work to improve the efficiency of the tool. In particular, we outline Clock Difference Diagrams (CDDs), new compact representations of states, a distributed version of the tool, and application of dynamic partitioning. UPPAAL has been applied in a number of academic and industrial case studies. We describe a selection of the recent case studies.

Formal Verification of UML Statecharts with Real-Time Extensions

Mobile work situations within home care of the elderly requireimmediate and ubiquitous access to patient-oriented data. We intend to develop a mobile information system that provides correct infor ...

An Efficient Decision Procedure for the Theory of Fixed-Sized Bit-Vectors

In this paper we describe a decision procedure for the core theory of fixed-sized bit-vectors with extraction and composition that can readily be integrated into Shostaks procedure for deciding combinations of theories. Inputs to the solver are unquantified bit-vector equations t=u and the algorithm returns true if t=u is valid in the bit-vector theory, false if t=u is unsatisfiable, and a system of solved equations otherwise. The time complexity of the solver is \(\mathcal{O}\left( {\left| t \right| \cdot log{\text{ }}n + n^2 } \right)\), where t is the length of the bit-vector term t and n denotes the number of bits on either side of the equation. Then, the solver for the core bit-vector theory is extended to handle other bit-vector operations like bitwise logical operations, shifting, and arithmetic interpretations of bit-vectors. We develop a BDD-like data-structure called bit-vector BDDs to represent bit-vectors, various operations on bit-vectors, and a solver on bit-vector BDDs.

Solving Bit-Vector Equations

This paper is concerned with solving equations on fixed and non-fixed size bit-vector terms. We define an equational transformation system for solving equations on terms where all sizes of bit-vectors and extraction positions are known. This transformation system suggests a generalization for dealing with bit-vectors of unknown size and unknown extraction positions. Both solvers adhere to the principle of splitting bitvectors only on demand, thereby making them quite effective in practice.