iii Acknowledgments This work would not have been possible without the support of many people inside and outside of New York University. My advisor, Professor Ralph Grishman, has provided me with a great deal of useful advice, including suggesting the problem of named entity recognition to me as a promising application for maximum entropy modeling. More than that, he has helped me work through a great deal of literature in statistical computational linguistics and he generously supplied me with the necessary time, equipment, and resources of his research staff which enabled me to put together the MENE system. I would also like to thank the other members of NYU's Proteus project for their assistance. In particular, John Sterling helped me to develop the idea of integrating the Proteus parser with the MENE system in the month before the MUC-7 evaluation. He and Eugene Agichtein put in extremely long hours leading up to the evaluation and helped to make it a success. The work on porting the MENE system to Japanese would not have been possible without the assistance of my friend and colleague, Satoshi Sekine. In addition, I would like to thank him for helping me out as the only English-speaking participant in the IREX evaluation. For his assistance with my upcoming trip to Japan and for all his work on translating IREX instructions for my benefit, I am very grateful.

Performance measurement of parallel, objectoriented (OO) programs requires the development of instrumentation and analysis techniques beyond those used for more traditional languages. Performance events must be redefined for the conceptual OO programming model, and those events must be instrumented and tracked in the context of OO language abstractions, compilation methods, and runtime execution dynamics. In this paper, we focus on the profiling and tracing of C++ applications that have been written using a rich parallel programming framework for highperformance, scientific computing. We address issues of class-based profiling, instrumentation of templates, runtime function identification, and polymorphic (type-based) profiling. Our solutions are implemented in the TAU portable profiling package which also provides support for profiling groups and userlevel timers. We demonstrate TAU's C++ profiling capabilities for real parallel applications, built from components of the ACTS toolkit....

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The developers of high-performance scientific applications often work in complex computing environments that place heavy demands on program analysis tools. The developers need tools that interoperate, are portable across machine architectures, and provide source-level feedback. In this paper, we describe a tool framework, the Program Database Toolkit (PDT), that supports the development of program analysis tools meeting these requirements. PDT uses compile-time information to create a complete database of high-level program information that is structured for well-defined and uniform access by tools and applications. PDT's current applications make heavy use of advanced features of C++, in particular, templates. We describe the toolkit, focussing on its most important contribution -- its handling of templates -- as well as its use in existing applications.

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ML-style modules are valuable in the development and maintenance of large software systems, unfortunately, none of the existing languages support them in a fully satisfactory manner. The official SML'97 Definition does not allow higher-order functors, so a module that refers to externally defined functors cannot accurately describe its import interface. MacQueen and ToRe [26] extended SML'97 with fully transparent higher-order functors, but their system does not have a type-theoretic semantics thus fails to support fully syntactic signatures. The systems of manifest types [19, 20] and translucent sums [12] support fully syntactic signatures but they may propagate fewer type equalities than fully transparent functors. This paper presents a module calculus that supports both fully transparent higher-order functors and fully syntactic signa- tures (and thus true separate compilation). We give a simple typetheoretic semantics to our calculus and show how to compile it into an F,-like )-calculus extended with existential types.

We define a practical algorithm for distributed rational tree unification and prove its correctness in both the off-line and on-line cases. We derive the distributed algorithm from a centralized one, showing clearly the trade-offs between local and distributed execution. The algorithm is used to realize logic variables in the Mozart Programming System, which implements the Oz language (see

The Standard Template Adaptive Parallel Library (STAPL) is a parallel library designed as a superset of the ANSI C++ Standard Template Library (STL). It is sequentially consistent for functions with the same name, and executes on uni- or multi-processor systems that utilize shared or distributed memory. STAPL is implemented using simple parallel extensions of C++ that currently provide a SPMD model of parallelism, and supports nested parallelism. The library is intended to be general purpose, but emphasizes irregular programs to allow the exploitation of parallelism for applications which use dynamically linked data structures such as particle transport calculations, molecular dynamics, geometric modeling, and graph algorithms. STAPL provides several different algorithms for some library routines, and selects among them adaptively at runtime. STAPL can replace STL automatically by invoking a preprocessing translation phase. In the applications studied, the performance of translated code was within 5 % of the results obtained using STAPL directly. STAPL also provides functionality to allow the user to further optimize the code and achieve additional performance gains. We present results obtained using STAPL for a molecular dynamics code and a particle transport code.

This paper presents a pragmatic way of implementing content-based publish/subscribe in a strongly typed object-oriented language. In short, we use structural reflection to implement filter objects through which applications express their subscription patterns. Our approach is pragmatic in the sense that it alleviates the need for any specific subscription language. It preserves encapsulation of message objects and helps avoiding errors. We illustrate our approach in the context of Distributed Asynchronous Collections (DACs), programming abstractions for message-oriented interaction. DACs are implemented in Java, whose inherent reflective capabilities fully satisfy the requirements of our content-based subscription scheme. Our approach is however not limited to the context of DACs, but could be put to work easily in other existing event-based systems.

Abstract. A systematic approach for implementing software product lines is more than just a selection of techniques. Its selection should be based on a systematic analysis of technical requirements and constraints, as well as of the types of variabilities, which occur in a particular application domain and are relevant for the planned product line (PL). In addition, each technique should provide a set of guidelines and criteria that support developers in applying the techniques in a systematic and unified way. This paper presents a case study that was performed to evaluate aspect-oriented programming (AOP) as a PL implementation technology. The systematical evaluation is organized along a general evaluation schema for PL implementation technologies. 1