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Concurrent real-time systems are among the most difficult systems to design because of the many possible interleavings of events and because of the timing requirements that must be satisfied. We have developed a graphical environment based on Real-Time Graphical Interval Logic (RTGIL) for specifying and reasoning about the designs of concurrent real-time(More)
This paper presents the design of Pharos: a scalable distributed architecture for locating heterogeneous information sources. The system incorporates a hierarchical metadata structure into a multi-level retrieval system. Queries are resolved through an iterative decision-making process. The rst step retrieves coarse-grain metadata, about all sources, stored(More)
This article describes a graphical interval logic that is the foundation of a tool set supporting formal specification and verification of concurrent software systems. Experience has shown that most software engineers find standard temporal logics difficult to understand and use. The objective of this article is to enable software engineers to specify and(More)
We present an interval logic, called Future Interval Logic (FIL), for the speciication and veriica-tion of concurrent systems. Interval logics allow reasoning to be carried out at the level of time intervals, rather than instants. However, unlike some other interval logics, the primitive objects in our semantic model for FIL are not intervals, but instants.(More)
—Amalia is a generator framework for constructing analyzers for operationally defined formal notations. These generated analyzers are components that are designed for customization and integration into a larger environment. The customizability and efficiency of Amalia analyzers owe to a computational structure called an inference graph. This paper describes(More)
Conceptual data models describe information systems without the burden of implementation details, and are increasingly used to generate code. They could also be analyzed for consistency and to generate test data except that the expressive constraints supported by popular modeling notations make such analysis intractable. In an earlier empirical study of(More)
The constrained expression approach to analysis of concurrent software systems has several attractive features, including the facts that it can be used with a variety of design and programming languages and that it does not require a complete enumeration of the set of reachable states of the concurrent system. This paper reports on the construction of a(More)
Verifying that test executions are correct is a crucial step in the testing process. Unfortunately, it can be a very arduous and error-prone step, especially when testing a concurrent system. System developers can therefore benefit from oracles automating the verification of test executions.This paper examines the use of Graphical Interval Logic (GIL) for(More)
This paper describes a generic tableau algorithm, which is the basis for a general customizable method for producing oracles from temporal logic specifications. A generic argument gives semantic rules with which to build the semantic tableau for a specification. Parameterizing the tableau algorithm by semantic rules permits it to easily accommodate a(More)
An approach to the design of concurrent software systems based on the constrained expression formalism is described. This formalism provides a rigorous conceptual model for the semantics of concurrent computations, thereby supporting analysis of important system properties as part of the design process. This approach allows designers to use standard(More)