16,163 research outputs found
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
Finite Bisimulations of Controllable Linear Systems
Finite abstractions of infinite state models have been critical in enabling and applying formal and algorithmic verification methods to continuous and hybrid systems. This has triggered the study and characterization of classes of continuous dynamics which can be abstracted by finite transition systems. In this paper, we focus on synthesis rather than analysis. In this spirit, we show that given any discrete-time, linear control system satisfying a generic controllability property, and any finite set of observations restricted to the boolean algebra of Brunovsky sets, a finite bisimulation always exists and can be effectively computed
HyPLC: Hybrid Programmable Logic Controller Program Translation for Verification
Programmable Logic Controllers (PLCs) provide a prominent choice of
implementation platform for safety-critical industrial control systems. Formal
verification provides ways of establishing correctness guarantees, which can be
quite important for such safety-critical applications. But since PLC code does
not include an analytic model of the system plant, their verification is
limited to discrete properties. In this paper, we, thus, start the other way
around with hybrid programs that include continuous plant models in addition to
discrete control algorithms. Even deep correctness properties of hybrid
programs can be formally verified in the theorem prover KeYmaera X that
implements differential dynamic logic, dL, for hybrid programs. After verifying
the hybrid program, we now present an approach for translating hybrid programs
into PLC code. The new tool, HyPLC, implements this translation of discrete
control code of verified hybrid program models to PLC controller code and, vice
versa, the translation of existing PLC code into the discrete control actions
for a hybrid program given an additional input of the continuous dynamics of
the system to be verified. This approach allows for the generation of real
controller code while preserving, by compilation, the correctness of a valid
and verified hybrid program. PLCs are common cyber-physical interfaces for
safety-critical industrial control applications, and HyPLC serves as a
pragmatic tool for bridging formal verification of complex cyber-physical
systems at the algorithmic level of hybrid programs with the execution layer of
concrete PLC implementations.Comment: 13 pages, 9 figures. ICCPS 201
Workshop on Verification and Theorem Proving for Continuous Systems (NetCA Workshop 2005)
Oxford, UK, 26 August 200
Sciduction: Combining Induction, Deduction, and Structure for Verification and Synthesis
Even with impressive advances in automated formal methods, certain problems
in system verification and synthesis remain challenging. Examples include the
verification of quantitative properties of software involving constraints on
timing and energy consumption, and the automatic synthesis of systems from
specifications. The major challenges include environment modeling,
incompleteness in specifications, and the complexity of underlying decision
problems.
This position paper proposes sciduction, an approach to tackle these
challenges by integrating inductive inference, deductive reasoning, and
structure hypotheses. Deductive reasoning, which leads from general rules or
concepts to conclusions about specific problem instances, includes techniques
such as logical inference and constraint solving. Inductive inference, which
generalizes from specific instances to yield a concept, includes algorithmic
learning from examples. Structure hypotheses are used to define the class of
artifacts, such as invariants or program fragments, generated during
verification or synthesis. Sciduction constrains inductive and deductive
reasoning using structure hypotheses, and actively combines inductive and
deductive reasoning: for instance, deductive techniques generate examples for
learning, and inductive reasoning is used to guide the deductive engines.
We illustrate this approach with three applications: (i) timing analysis of
software; (ii) synthesis of loop-free programs, and (iii) controller synthesis
for hybrid systems. Some future applications are also discussed
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