52 research outputs found
UPPAAL-Tiga: Timed Games for Everyone
In 2005 we proposed the first efficient on-the-fly algorithm for solving games based on timed game automata with respect to reachability and safety properties. Since then we have completely re-implemented the first prototype and made dramatic improvements both in terms of performance (several orders of magnitude) and the input language (complete support of all the language features of Uppaal). In addition, the tool supports the new feature of strategy generation with different compactness levels. In this paper we present this new version of Uppaal-Tiga
On Consistency of Operational Transformation Approach
The Operational Transformation (OT) approach, used in many collaborative
editors, allows a group of users to concurrently update replicas of a shared
object and exchange their updates in any order. The basic idea of this approach
is to transform any received update operation before its execution on a replica
of the object. This transformation aims to ensure the convergence of the
different replicas of the object, even though the operations are executed in
different orders. However, designing transformation functions for achieving
convergence is a critical and challenging issue. Indeed, the transformation
functions proposed in the literature are all revealed incorrect.
In this paper, we investigate the existence of transformation functions for a
shared string altered by insert and delete operations. From the theoretical
point of view, two properties - named TP1 and TP2 - are necessary and
sufficient to ensure convergence. Using controller synthesis technique, we show
that there are some transformation functions which satisfy only TP1 for the
basic signatures of insert and delete operations. As a matter of fact, it is
impossible to meet both properties TP1 and TP2 with these simple signatures.Comment: In Proceedings Infinity 2012, arXiv:1302.310
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
A Backward Algorithm for the Multiprocessor Online Feasibility of Sporadic Tasks
The online feasibility problem (for a set of sporadic tasks) asks whether
there is a scheduler that always prevents deadline misses (if any), whatever
the sequence of job releases, which is a priori} unknown to the scheduler. In
the multiprocessor setting, this problem is notoriously difficult. The only
exact test for this problem has been proposed by Bonifaci and
Marchetti-Spaccamela: it consists in modelling all the possible behaviours of
the scheduler and of the tasks as a graph; and to interpret this graph as a
game between the tasks and the scheduler, which are seen as antagonistic
players. Then, computing a correct scheduler is equivalent to finding a winning
strategy for the `scheduler player', whose objective in the game is to avoid
deadline misses. In practice, however this approach is limited by the
intractable size of the graph. In this work, we consider the classical
attractor algorithm to solve such games, and introduce antichain techniques to
optimise its performance in practice and overcome the huge size of the game
graph. These techniques are inspired from results from the formal methods
community, and exploit the specific structure of the feasibility problem. We
demonstrate empirically that our approach allows to dramatically improve the
performance of the game solving algorithm.Comment: Long version of a conference paper accepted to ACSD 201
Enriching APSI with Validation Capabilities: the KEEN environment and its use in Robotics
This paper presents the KnowledgE ENgineering (KEEN) design support system in which Validation and Verification (V&V) methods are used to strengthen onground development of software for plan-based autonomy. In particular, the paper describes a collection of verification methods, based on Timed Game Automata (TGA), deployed for the design and development of timeline-based Planning and Scheduling (P&S) applications within the APSI-TRF framework. The KEENs V&V functionalities are illustrated describing software development to synthesize plans for a planetary rover
Synthesis of orchestrations of transducers for manufacturing
In this paper, we model manufacturing processes and facilities as transducers (automata with output). The problem of whether a given manufacturing process can be realized by a given set of manufacturing resources can then be stated as an orchestration problem for transducers. We first consider the conceptually simpler case of uni-transducers (transducers with a single input and a single output port), and show that synthesizing orchestrations for uni-transducers is EXPTIME complete. Surprisingly, the complexity remains the same for the more expressive multi-transducer case, where transducers have multiple input and output ports and the orchestration is in charge of dynamically connecting ports during execution
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