Abstract. Real-Time Maude is a language and tool supporting the formal specification and analysis of real-time and hybrid systems. The specification formalism is based on rewriting logic, emphasizes generality and ease of specification, and is particularly suitable to specify objectoriented real-time systems. The tool offers a wide range of analysis techniques, including timed rewriting for simulation purposes, search, and time-bounded linear temporal logic model checking. It has been used to model and analyze sophisticated communication protocols and scheduling algorithms. Real-Time Maude is an extension of Maude and a major redesign of an earlier prototype. Tools based on timed and linear hybrid automata, such as Uppaal [1], HyTech [2], and Kronos [3], have been successful in modeling and analyzing an impressive collection of real-time systems. While their restrictive specification formalism ensures that interesting properties are decidable, such finite-control automata do not support well the specification of larger systems with different

This paper describes the application of Real-Time Maude to the formal specification, simulation, and further formal analysis of the sophisticated state-of-the-art OGDC wireless sensor network algorithm. Wireless sensor networks in general, and the OGDC algorithm in particular, pose many challenges to their formal specification and analysis, including novel communication forms, treatment of geographic areas, time-dependent and probabilistic features, and the need to analyze both correctness and performance. Real-Time Maude extends the rewriting logic tool Maude to support formal specification and analysis of objectbased real-time systems. This paper explains how we formally specified OGDC in Real-Time Maude, how we could simulate our specification to perform all the analyses done by the algorithm developers using the network simulation tool ns-2, and how we could perform further formal analyses which are beyond the capabilities of simulation tools. A remarkable result is that our Real-Time Maude simulations seem to provide a much more accurate estimate of the performance of OGDC than the ns-2 simulations. To the best of our knowledge, this is the first time a formal tool has been applied to an advanced wireless sensor network algorithm.

Abstract. This paper describes the application of the Real-Time Maude tool to the formal specification and analysis of the CASH scheduling algorithm and its suggested modifications. The CASH algorithm is a sophisticated state-of-the-art scheduling algorithm with advanced capacity sharing features for reusing unused execution budgets. Because the number of elements in the queue of unused resources can grow beyond any bound, the CASH algorithm poses challenges to its formal specification and analysis. Real-Time Maude extends the rewriting logic tool Maude to support formal specification and analysis of object-based real-time systems. It emphasizes generality of specification and supports a spectrum of analysis methods, including symbolic simulation and (unbounded and time-bounded) reachability analysis and LTL model checking. We show how we have used Real-Time Maude to experiment with different design modifications of the CASH algorithm using both Monte Carlo simulation and reachability analysis. We could quickly and easily specify and analyze these modifications using Real-Time Maude, and discovered subtle behaviors in the modifications that lead to missed deadlines. 1

Abstract ∗ The highly dynamic nature and stringent timing constraints of distributed, real-time, and embedded (DRE) systems lead to complex cross-layer interactions and valid designs must satisfy a multitude of constraints. In this paper, we focus our attention on design validation considering multidimensional interoperability in the context of cross-layer approaches for power optimization under timing constraints in distributed mobile systems. Specifically, we (i) formally specify each layer of abstraction in consort with timing and energy properties, and (ii) evaluate an optimized policy for design validation as well as provide a time-energy critical path for further optimization that will cost-effectively address the Quality of Service (QoS)/performance tradeoffs. By providing a design flow that includes both timing verification and cross layer optimization, we can achieve (i) timing guarantees for design verification, (ii) better optimizations for resource management, and (iii) adaptive parameter settings for resource sharing and energy minimization. We present preliminary results on an MPEG application. 1

Abstract. This paper describes the main features of several tools concerned with the analysis of either Maude specifications, or of extensions of such specifications: the ITP, MTT, CRC, ChC, and SCC tools, and Real-Time Maude for real-time systems. These tools, together with Maude itself and its searching and model-checking capabilities constitute Maude’s formal environment. 1

Abstract. Algorithmic skeletons are a well-known approach for implementing parallel and distributed applications. Declarative versions typically use higher-order functions in functional languages. We show here a different approach based on object-oriented parameterized modules in Maude, that receive the operations needed to solve a concrete problem as a parameter. Architectures are conceived separately from the skeletons that are executed on top of them. The object-oriented methodology followed facilitates nesting of skeletons and the combination of architectures. Maude analysis tools allow to check at different abstraction levels properties of the applications built by instantiating a skeleton.

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AADL (Architectural Analysis and Design Language) is a textual and graphical language used to design and analyze software architecture of embedded real time systems. Many tools and models provide semantics and precise meaning for AADL architecture behavior. However, they are not supported by a well defined formal semantics. This paper suggets Rewriting Logic via its practical language Maude as an adequate formalism for modeling behavior concepts in an AADL architectural description. Besides, RT-Maude system offers a natural support to execute and prototype real-time object-oriented modules formalizing AADL architecture behavior composed of several communicating threads.

This paper presents criteria that guarantee completeness of Real-Time Maude search and temporal logic model checking analyses, under the maximal time sampling strategy, for a large class of real-time systems. As a special case, we characterize simple conditions for such completeness for object-oriented real-time systems, and show that these conditions can often be easily proved even for large and complex systems, such as advanced wireless sensor network algorithms and active network multicast protocols. Our results provide completeness and decidability of time-bounded search and model checking for a large and useful class of dense-time non-Zeno real-time systems far beyond the class of automaton-based real-time systems for which well known decision procedures exist. For discrete time, our results justify stutteringbisimilar abstractions that can drastically reduce the state space to make search and model checking analyses feasible.