96 research outputs found
Quantitative Verification in Practice
Soon after the birth of model checking, the first theoretical achievements have been reported on the automated verification of quanti- tative system aspects such as discrete probabilities and continuous time. These theories have been extended in various dimensions, such as con- tinuous probabilities, cost constraints, discounting, hybrid phenomena, and combinations thereof. Due to unremitting improvements of under- lying algorithms and data structures, together with the availability of more advanced computing engines, these techniques are nowadays appli- cable to realistic designs. Powerful software tools allow these techniques to be applied by non-specialists, and efforts have been made to embed these techniques into industrial system design processes. Quantitative verification has a broad application potential â successful applications in embedded system design, hardware, security, safety-critical software, schedulability analysis, and systems biology exemplify this. It is fair to say, that over the years this application area grows rapidly and there is no sign that this will not continue. This session reports on applying state-of-the-art quantitative verification techniques and tools to a variety of industrial case studies
Observer-based correct-by-design controller synthesis
Current state-of-the-art correct-by-design controllers are designed for
full-state measurable systems. This work first extends the applicability of
correct-by-design controllers to partially observable LTI systems. Leveraging
2nd order bounds we give a design method that has a quantifiable robustness to
probabilistic disturbances on state transitions and on output measurements. In
a case study from smart buildings we evaluate the new output-based
correct-by-design controller on a physical system with limited sensor
information
A linear time algorithm for the orbit problem over cyclic groups
The orbit problem is at the heart of symmetry reduction methods for model
checking concurrent systems. It asks whether two given configurations in a
concurrent system (represented as finite strings over some finite alphabet) are
in the same orbit with respect to a given finite permutation group (represented
by their generators) acting on this set of configurations by permuting indices.
It is known that the problem is in general as hard as the graph isomorphism
problem, whose precise complexity (whether it is solvable in polynomial-time)
is a long-standing open problem. In this paper, we consider the restriction of
the orbit problem when the permutation group is cyclic (i.e. generated by a
single permutation), an important restriction of the problem. It is known that
this subproblem is solvable in polynomial-time. Our main result is a
linear-time algorithm for this subproblem.Comment: Accepted in Acta Informatica in Nov 201
Software Verification and Graph Similarity for Automated Evaluation of Students' Assignments
In this paper we promote introducing software verification and control flow
graph similarity measurement in automated evaluation of students' programs. We
present a new grading framework that merges results obtained by combination of
these two approaches with results obtained by automated testing, leading to
improved quality and precision of automated grading. These two approaches are
also useful in providing a comprehensible feedback that can help students to
improve the quality of their programs We also present our corresponding tools
that are publicly available and open source. The tools are based on LLVM
low-level intermediate code representation, so they could be applied to a
number of programming languages. Experimental evaluation of the proposed
grading framework is performed on a corpus of university students' programs
written in programming language C. Results of the experiments show that
automatically generated grades are highly correlated with manually determined
grades suggesting that the presented tools can find real-world applications in
studying and grading
Data-driven and Model-based Verification: a Bayesian Identification Approach
This work develops a measurement-driven and model-based formal verification
approach, applicable to systems with partly unknown dynamics. We provide a
principled method, grounded on reachability analysis and on Bayesian inference,
to compute the confidence that a physical system driven by external inputs and
accessed under noisy measurements, verifies a temporal logic property. A case
study is discussed, where we investigate the bounded- and unbounded-time safety
of a partly unknown linear time invariant system
Modelling IEEE 802.11 CSMA/CA RTS/CTS with stochastic bigraphs with sharing
Stochastic bigraphical reactive systems (SBRS) is a recent formalism for modelling systems that evolve
in time and space. However, the underlying spatial model is based on sets of trees and thus cannot represent
spatial locations that are shared among several entities in a simple or intuitive way. We adopt an extension of
the formalism, SBRS with sharing, in which the topology is modelled by a directed acyclic graph structure. We
give an overview of SBRS with sharing, we extend it with rule priorities, and then use it to develop a model
of the 802.11 CSMA/CA RTS/CTS protocol with exponential backoff, for an arbitrary network topology with
possibly overlapping signals. The model uses sharing to model overlapping connectedness areas, instantaneous
prioritised rules for deterministic computations, and stochastic rules with exponential reaction rates to model
constant and uniformly distributed timeouts and constant transmission times. Equivalence classes of model states
modulo instantaneous reactions yield states in a CTMC that can be analysed using the model checker PRISM.
We illustrate the model on a simple example wireless network with three overlapping signals and we present some
example quantitative properties
High-level Counterexamples for Probabilistic Automata
Providing compact and understandable counterexamples for violated system
properties is an essential task in model checking. Existing works on
counterexamples for probabilistic systems so far computed either a large set of
system runs or a subset of the system's states, both of which are of limited
use in manual debugging. Many probabilistic systems are described in a guarded
command language like the one used by the popular model checker PRISM. In this
paper we describe how a smallest possible subset of the commands can be
identified which together make the system erroneous. We additionally show how
the selected commands can be further simplified to obtain a well-understandable
counterexample
- âŠ