Algorithmic Verification of Continuous and Hybrid Systems

We provide a tutorial introduction to reachability computation, a class of computational techniques that exports verification technology toward continuous and hybrid systems. For open under-determined systems, this technique can sometimes replace an infinite number of simulations.Comment: In Proceedings INFINITY 2013, arXiv:1402.661

Formal and Informal Methods for Multi-Core Design Space Exploration

We propose a tool-supported methodology for design-space exploration for embedded systems. It provides means to define high-level models of applications and multi-processor architectures and evaluate the performance of different deployment (mapping, scheduling) strategies while taking uncertainty into account. We argue that this extension of the scope of formal verification is important for the viability of the domain.Comment: In Proceedings QAPL 2014, arXiv:1406.156

On Zone-Based Analysis of Duration Probabilistic Automata

We propose an extension of the zone-based algorithmics for analyzing timed automata to handle systems where timing uncertainty is considered as probabilistic rather than set-theoretic. We study duration probabilistic automata (DPA), expressing multiple parallel processes admitting memoryfull continuously-distributed durations. For this model we develop an extension of the zone-based forward reachability algorithm whose successor operator is a density transformer, thus providing a solution to verification and performance evaluation problems concerning acyclic DPA (or the bounded-horizon behavior of cyclic DPA).Comment: In Proceedings INFINITY 2010, arXiv:1010.611

Numerical Verification of Affine Systems with up to a Billion Dimensions

Affine systems reachability is the basis of many verification methods. With further computation, methods exist to reason about richer models with inputs, nonlinear differential equations, and hybrid dynamics. As such, the scalability of affine systems verification is a prerequisite to scalable analysis for more complex systems. In this paper, we improve the scalability of affine systems verification, in terms of the number of dimensions (variables) in the system. The reachable states of affine systems can be written in terms of the matrix exponential, and safety checking can be performed at specific time steps with linear programming. Unfortunately, for large systems with many state variables, this direct approach requires an intractable amount of memory while using an intractable amount of computation time. We overcome these challenges by combining several methods that leverage common problem structure. Memory is reduced by exploiting initial states that are not full-dimensional and safety properties (outputs) over a few linear projections of the state variables. Computation time is saved by using numerical simulations to compute only projections of the matrix exponential relevant for the verification problem. Since large systems often have sparse dynamics, we use Krylov-subspace simulation approaches based on the Arnoldi or Lanczos iterations. Our method produces accurate counter-examples when properties are violated and, in the extreme case with sufficient problem structure, can analyze a system with one billion real-valued state variables

Formal Methods for the Synthesis of Biomolecular Circuits

This report documents the program and the outcomes of Dagstuhl Seminar 18082 "Formal Methods for the Synthesis of Biomolecular Circuits". Synthetic biology aims for the rational bottom-up engineering of new biological functionalities. Recent years have witnessed an increase in the degree of "rationality" in the design of synthetic biomolecular circuits. With it, fewer design-build-test cycles were necessary to achieve a desired circuit performance. Most of these success stories reported the realization of logic circuits, typically operating via regulation of gene expression and/or direct manipulation of DNA sequences with recombinases, executing combinatorial and sometimes sequential logic. This was often achieved with the help of two ingredients, a library of previously well-characterized parts and some computational modeling. Hence, although circuits in synthetic biology are still by far less understood and characterized than electronic circuits, the opportunity for the formal synthesis of circuit designs with respect to a behavioral specification starts to emerge in synthetic biology

Many-Core Scheduling of Data Parallel Applications Using SMT Solvers

Abstract—To program recently developed many-core systems-on-chip two traditionally separate performance optimization problems have to be solved together. Firstly, it is the parallel scheduling on a shared-memory multi-core system. Secondly, it is the co-scheduling of network communication and processor computation. This is because many-core systems are networks of multi-core clusters. In this paper, we demonstrate the applicabil-ity of modern constraint solvers to efficiently schedule parallel applications on many-cores and validate the results by running benchmarks on a real many-core platform. Index Terms—task graph, scheduling, multiprocessor, DMA I

LNCS

We introduce in this paper AMT 2.0 , a tool for qualitative and quantitative analysis of hybrid continuous and Boolean signals that combine numerical values and discrete events. The evaluation of the signals is based on rich temporal specifications expressed in extended Signal Temporal Logic (xSTL), which integrates Timed Regular Expressions (TRE) within Signal Temporal Logic (STL). The tool features qualitative monitoring (property satisfaction checking), trace diagnostics for explaining and justifying property violations and specification-driven measurement of quantitative features of the signal