Discovering different types of file resources (such as documentation, programs, and images) in the vast amount of data contained within network file systems is useful for both users and system administrators. In this paper we discuss the Essence resource discovery system, which exploits file semantics to index both textual and binary files. By exploiting semantics, Essence extracts keywords that summarize a file, and generates a compact yet representative index. Essence understands nested file structures (such as uuencoded, compressed, "tar" files), and recursively unravels such files to generate summaries for them. These features allow Essence to be used in a number of useful settings, such as anonymous FTP archives. We present measurements of our prototype and compare them to related projects, such as the Wide Area Information Servers (WAIS) system and the MIT Semantic File System (SFS). We demonstrate that Essence can index more data types, generate smaller indexes, and in some case...

Procedure calling conventions are used to provide uniform procedure -call interfaces. Applications, such as compilers and debuggers, which generate, or process procedures at the machinelanguage abstraction level require knowledge of the calling convention. In this paper, we develop a formal model for procedure calling conventions called P-FSA's. Using this model, we are able to ensure several completeness and consistency properties of calling conventions. Currently, applications that manipulate procedures implement conventions in an ad-hoc manner. The resulting code is complicated with details, difficult to maintain, and often riddled with errors. To alleviate the situation, we introduce a calling convention specification language, called CCL. The combination of CCL and P-FSA's facilitates the accurate specification of conventions that can be shown to be both consistent and complete. 1 Introduction Procedures, or functions, in programming languages work in concert to implement the in...

We investigate the balancing of distributed compressed storage of large sparse matrices on a massively parallel computer. For fast computation of matrix-vector and matrix-matrix products on a rectangular processor array with efficient communications along its rows and columns we require that the nonzero elements of each matrix row or column be distributed among the processors located within the same array row or column, respectively. We construct randomized packing algorithms with such properties, and we prove that with high probability they produce well-balanced storage for sufficiently large matrices with bounded number of nonzeros in each row and column, but no other restrictions on structure. Then we design basic matrix-vector multiplication routines with fully parallel interprocessor communications and intraprocessor gather and scatter operations. Their efficiency is demonstrated on the 16,384-processor MasPar computer.

The Unified Modeling Language is becoming more and more popular in the software development. However because of its ambiguisity in its semantic model, few verification tool has been built. Abstract State Machines have been successfully applied in giving semantics for programming language like C. In this report, we try to use the Abstract State Machines to give a semantics model for UML and then use ASM Model Checker to design a verification tool for UML. Last we give a toy example to show how the verification tool works.

Abstract not found

In these notes we will review the automata-theoretic verification method and propositional linear temporal logic, with specific emphasis on their potential application to distributed software verification. An important

Flight software is the central nervous system of modern spacecraft. Verifying spacecraft flight software to assure that it operates correctly and safely is presently an intensive and costly process. A multitude of scenarios and tests must be devised, executed and reviewed to provide reasonable confidence that the software will perform as intended and not endanger the spacecraft. Undetected software defects on spacecraft and launch vehicles have caused embarrassing and costly failures in recent years.

Most software developers today rely on only a small number of techniques to check their code for defects: peer review, code walkthroughs, and testing. Despite a rich literature on these subjects, the results often leave much to be desired. The current software testing process consumes a significant fraction of the overall resources in industrial software development, yet it cannot promise zero-defect code. There is reason to hope that the process can be improved. A range of tools and techniques has become available in the last few years that can asses the quality of code with considerably more rigor than before, and often also with more ease. Many of the new tools can be understood as applications of automata theory, and can readily be combined with logic model checking techniques.

Abstract. We introduce an adaptation of run-relaxed heaps which provides efficient heap operations with respect to the number of element comparisons performed. Our data structure guarantees the worst-case cost of O(1) for find-min, insert, and decrease; and the worst-case cost of O(lg n) with at most lg n + 3 lg lg n + O(1) element comparisons for delete, improving the bound of 3lg n + O(1) on the number of element comparisons known for run-relaxed heaps. Here, n denotes the number of elements stored prior to the operation in question, and lg n equals max {1, log 2 n}. 1

This paper presents a multiparadigm language I + which is an integration of the three major programming paradigms: object-oriented, logic and functional. I + has an object-oriented framework in which the notions of classes, objects, methods, inheritance and message passing are supported. Methods may be specified as clauses or functions, thus the two declarative paradigms are incorporated at the method level of the object-oriented paradigm. In addition, two levels of parallelism may be exploited in I + programming. Therefore I + is a multiparadigm language for object-oriented declarative programming as well as parallel programming. Keywords: Multiparadigm, Object-oriented paradigm , Logic paradigm , Functional paradigm 1 Introduction A multiparadigm language is a language that supports more than one programming paradigm. Multiparadigm languages are desirable for the following reasons: . A programmer can choose the most appropriate paradigm for a particular problem at hand so that...