127,357 research outputs found
Time Window Temporal Logic
This paper introduces time window temporal logic (TWTL), a rich expressivity
language for describing various time bounded specifications. In particular, the
syntax and semantics of TWTL enable the compact representation of serial tasks,
which are typically seen in robotics and control applications. This paper also
discusses the relaxation of TWTL formulae with respect to deadlines of tasks.
Efficient automata-based frameworks to solve synthesis, verification and
learning problems are also presented. The key ingredient to the presented
solution is an algorithm to translate a TWTL formula to an annotated finite
state automaton that encodes all possible temporal relaxations of the
specification. Case studies illustrating the expressivity of the logic and the
proposed algorithms are included
Time window temporal logic
This paper introduces time window temporal logic (TWTL), a rich expressive language for describing various time bounded specifications. In particular, the syntax and semantics of TWTL enable the compact representation of serial tasks, which are prevalent in various applications including robotics, sensor systems, and manufacturing systems. This paper also discusses the relaxation of TWTL formulae with respect to the deadlines of the tasks. Efficient automata-based frameworks are presented to solve synthesis, verification and learning problems. The key ingredient to the presented solution is an algorithm to translate a TWTL formula to an annotated finite state automaton that encodes all possible temporal relaxations of the given formula. Some case studies are presented to illustrate the expressivity of the logic and the proposed algorithms
Robustness Measures and Monitors for Time Window Temporal Logic
Temporal logics (TLs) have been widely used to formalize interpretable tasks
for cyber-physical systems. Time Window Temporal Logic (TWTL) has been recently
proposed as a specification language for dynamical systems. In particular, it
can easily express robotic tasks, and it allows for efficient, automata-based
verification and synthesis of control policies for such systems. In this paper,
we define two quantitative semantics for this logic, and two corresponding
monitoring algorithms, which allow for real-time quantification of satisfaction
of formulas by trajectories of discrete-time systems. We demonstrate the new
semantics and their runtime monitors on numerical examples.Comment: Submitted to the 62nd IEEE Conference on Decision and Control
(CDC2023
On Implementing Temporal Query Answering in DL-Lite
Ontology-based data access augments classical query answering over fact bases by adopting the open-world assumption and by including domain knowledge provided by an ontology. We implemented temporal query answering w.r.t. ontologies formulated in the Description Logic DL-Lite. Focusing on temporal conjunctive queries (TCQs), which combine conjunctive queries via the operators of propositional linear temporal logic, we regard three approaches for answering them: an iterative algorithm that considers all data available; a window-based algorithm; and a rewriting approach, which translates the TCQs to be answered into SQL queries. Since the relevant ontological knowledge is already encoded into the latter queries, they can be answered by a standard database system. Our evaluation especially shows that implementations of both the iterative and the window-based algorithm answer TCQs within a few milliseconds, and that the former achieves a constant performance, even if data is growing over time
Log Analysis Using Temporal Logic and Reconstruction Approach: Web Server Case
We present a post-mortem log analysis method based on Temporal Logic (TL), Event Processing Language (EPL), and reconstruction approach. After showing that the proposed method could be adapted to any misuse event or attack, we specifically investigate the case of web server misuses. To this end, we examine 5 different misuses on Wordpress web servers, and generate corresponding log files of these attacks for forensic analysis. Then we establish attack patterns and formalize them by means of a special case of temporal logic, i.e. many sorted first order metric temporal logic (MSFOMTL). Later on, we implement these attack patterns in the EPL, and performed experimental log analysis by using a time window mechanism sliding on sorted log records to evaluate effectiveness and efficacy of our proposed method. We found that our approach is potentially capable of providing a platform where investigators can define/store/share misuse patterns using a common language while providing fast and accurate forensic analysis on large log files
On the Complexity of Verifying Timed Golog Programs over Description Logic Actions: Extended Version
Golog programs allow to model complex behaviour of agents by combining primitive actions defined in a Situation Calculus theory using imperative and non-deterministic programming language constructs. In general, verifying temporal properties of Golog programs is undecidable. One way to establish decidability is to restrict the logic used by the program to a Description Logic (DL), for which recently some complexity upper bounds for verification problem have been established. However, so far it was open whether these results are tight, and lightweight DLs such as EL have not been studied at all. Furthermore, these results only apply to a setting where actions do not consume time, and the properties to be verified only refer to the timeline in a qualitative way. In a lot of applications, this is an unrealistic assumption. In this work, we study the verification problem for timed Golog programs, in which actions can be assigned differing durations, and temporal properties are specified in a metric branching time logic. This allows to annotate temporal properties with time intervals over which they are evaluated, to specify for example that some property should hold for at least n time units, or should become specified within some specified time window. We establish tight complexity bounds of the verification problem for both expressive and lightweight DLs. Our lower bounds already apply to a very limited fragment of the verification problem, and close open complexity bounds for the non-metrical cases studied before
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