36,898 research outputs found
Explicit Clock Temporal Logic in Timing Constraints for Real-Time Systems
A form of explicit clock temporal logic (called TLrt) useful in specifying timing constraints on controller actions, a real-time database (rtdb) items, and constraints in a real-time constraint base (rtcb), is presented. Timing as well as other forms of constraints are stored in the rtcb. A knowledge-based approach to ensure the integrity of information in an rtdb is given. The rtcb is realized as a logic program called Constrainer, which is a historyless integrity checker for a real-time database. The consistency and integrity issues for an rtcb and rtdb are investigated. The formal bases for a temporally complete rtdb and knowledgeably complete controller are presented. A partial TLrt specification of a knowledgeable controller for a Gas Burner is given. An illustration of a rtdb and rtcb in the context of the sample real-time system is also given
Real-time and Probabilistic Temporal Logics: An Overview
Over the last two decades, there has been an extensive study on logical
formalisms for specifying and verifying real-time systems. Temporal logics have
been an important research subject within this direction. Although numerous
logics have been introduced for the formal specification of real-time and
complex systems, an up to date comprehensive analysis of these logics does not
exist in the literature. In this paper we analyse real-time and probabilistic
temporal logics which have been widely used in this field. We extrapolate the
notions of decidability, axiomatizability, expressiveness, model checking, etc.
for each logic analysed. We also provide a comparison of features of the
temporal logics discussed
Constructing Real-Time Systems from Temporal I/O Automata
A new class of communicating automata called Temporal Input/Output Automata (TAi/os) is introduced. A TAi/o is a predicate automaton used to specify real-time systems. The specification provided by a TAi/o includes state predicates with proof expressions and abstract program syntax as attributes. An abstract program is extracted during a constructive proof of the specification using the proof expressions. A TAi/o specification also includes hard, real-time constraints on program behavior. The predictability of deterministic, temporally complete TAi/o is investigated. The formulation of real-time system transductions and transduction rules for TAi/os in explicit clock temporal logic is given. An illustration of the use of TAi/os in specifying light-controlled vehicles is presented. To illustrate the methodology in constructive reasoning about a TAi/o, a proof which derives a partial abstract program is given
Deciding the Satisfiability of MITL Specifications
In this paper we present a satisfiability-preserving reduction from MITL
interpreted over finitely-variable continuous behaviors to Constraint LTL over
clocks, a variant of CLTL that is decidable, and for which an SMT-based bounded
satisfiability checker is available. The result is a new complete and effective
decision procedure for MITL. Although decision procedures for MITL already
exist, the automata-based techniques they employ appear to be very difficult to
realize in practice, and, to the best of our knowledge, no implementation
currently exists for them. A prototype tool for MITL based on the encoding
presented here has, instead, been implemented and is publicly available.Comment: In Proceedings GandALF 2013, arXiv:1307.416
Logics of Temporal-Epistemic Actions
We present Dynamic Epistemic Temporal Logic, a framework for reasoning about
operations on multi-agent Kripke models that contain a designated temporal
relation. These operations are natural extensions of the well-known "action
models" from Dynamic Epistemic Logic. Our "temporal action models" may be used
to define a number of informational actions that can modify the "objective"
temporal structure of a model along with the agents' basic and higher-order
knowledge and beliefs about this structure, including their beliefs about the
time. In essence, this approach provides one way to extend the domain of action
model-style operations from atemporal Kripke models to temporal Kripke models
in a manner that allows actions to control the flow of time. We present a
number of examples to illustrate the subtleties involved in interpreting the
effects of our extended action models on temporal Kripke models. We also study
preservation of important epistemic-temporal properties of temporal Kripke
models under temporal action model-induced operations, provide complete
axiomatizations for two theories of temporal action models, and connect our
approach with previous work on time in Dynamic Epistemic Logic
Modeling and Analyzing Adaptive User-Centric Systems in Real-Time Maude
Pervasive user-centric applications are systems which are meant to sense the
presence, mood, and intentions of users in order to optimize user comfort and
performance. Building such applications requires not only state-of-the art
techniques from artificial intelligence but also sound software engineering
methods for facilitating modular design, runtime adaptation and verification of
critical system requirements.
In this paper we focus on high-level design and analysis, and use the
algebraic rewriting language Real-Time Maude for specifying applications in a
real-time setting. We propose a generic component-based approach for modeling
pervasive user-centric systems and we show how to analyze and prove crucial
properties of the system architecture through model checking and simulation.
For proving time-dependent properties we use Metric Temporal Logic (MTL) and
present analysis algorithms for model checking two subclasses of MTL formulas:
time-bounded response and time-bounded safety MTL formulas. The underlying idea
is to extend the Real-Time Maude model with suitable clocks, to transform the
MTL formulas into LTL formulas over the extended specification, and then to use
the LTL model checker of Maude. It is shown that these analyses are sound and
complete for maximal time sampling. The approach is illustrated by a simple
adaptive advertising scenario in which an adaptive advertisement display can
react to actions of the users in front of the display.Comment: In Proceedings RTRTS 2010, arXiv:1009.398
Verifying Real-Time Systems using Explicit-time Description Methods
Timed model checking has been extensively researched in recent years. Many
new formalisms with time extensions and tools based on them have been
presented. On the other hand, Explicit-Time Description Methods aim to verify
real-time systems with general untimed model checkers. Lamport presented an
explicit-time description method using a clock-ticking process (Tick) to
simulate the passage of time together with a group of global variables for time
requirements. This paper proposes a new explicit-time description method with
no reliance on global variables. Instead, it uses rendezvous synchronization
steps between the Tick process and each system process to simulate time. This
new method achieves better modularity and facilitates usage of more complex
timing constraints. The two explicit-time description methods are implemented
in DIVINE, a well-known distributed-memory model checker. Preliminary
experiment results show that our new method, with better modularity, is
comparable to Lamport's method with respect to time and memory efficiency
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