Stefan Disch

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We propose algorithms significantly extending the limits for maintaining exact representations in the verification of linear hybrid systems with large discrete state spaces. We use AND-Inverter Graphs (AIGs) extended with linear constraints (LinAIGs) as symbolic representation of the hybrid state space, and show how methods for maintaining compactness of(More)
We address the problem of model checking hybrid systems which exhibit nontrivial discrete behavior and thus cannot be treated by considering the discrete states one by one, as most currently available verification tools do. Our procedure relies on a deep integration of several techniques and tools. A first-order extension of AND-Inverter-Graphs (AIGs)(More)
We present a method which computes optimized representations for non-convex polyhedra. Our method detects so-called redundant linear constraints in these representations by using an incremental SMT (Satisfiability Modulo Theories) solver and then removes the redundant constraints based on Craig interpolation. The approach is motivated by applications in the(More)
— In this paper we present a complete method for verifying properties expressed in the temporal logic CTL. In contrast to the majority of verification methods presented in recent years, we support unbounded model checking based on symbolic representations of characteristic functions. Among others, our method is based on an advanced And-Inverter Graph (AIG)(More)
— Combinational equivalence checking is an essential task in circuit design. In this paper we focus on SAT based equivalence checking making use of incremental SAT techniques which are well known from their application in Bounded Model Checking. Based on an analysis of shared circuit structures we present heuristics which try to maximize the benefit from(More)
In this paper we present a complete method for verifying properties expressed in the temporal logic CTL. In contrast to the majority of verification methods presented in recent years, we support unbounded model checking based on symbolic representations of characteristic functions. Among others, our method is based on an advanced And-Inverter Graph (AIG)(More)
—Craig interpolation has turned out to be an essential method for many applications in formal verification. In this paper we focus on the computation of simple interpolants for the theory of linear arithmetic with rational coefficients. We successfully minimize the number of linear constraints in the final interpolant by several methods including proof(More)
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