1093169
An Embedded Language Approach to Router Specification in Curry
The development of modern routers require a significant effort to be designed, built, and verified. While hardware routers are faster, they are difficult to configure and maintain. Software routers, on the other hand, are slower but much more flexible, easier to configure and maintain, less expensive, etc. Recently, a modular architecture and toolkit for building software routers and other packet processors has been introduced: the Click system. It includes a specification language with features for declaring and connecting router elements and for designing abstractions.
2088546
Combining algorithmic debugging and program slicing
Currently, program slicing and algorithmic debugging are two of the most relevant debugging techniques for declarative languages. They help programmers to find bugs in a semiautomatic manner. On the one hand, program slicing is a technique to extract those program fragments that (potentially) affect the values computed at some point of interest. On the other hand, algorithmic debugging is able to locate a bug by automatically generating a series of questions and processing the programmer's answers. In this work, we show for functional languages how the combination of both techniques produces a more powerful debugging schema that reduces the number of questions that programmers must answer to locate a bug
5417799
Slicing XML Documents
Program slicing is a well-known technique to extract the program statements that (potentially) affect the values computed at some point of interest. In this work, we introduce a novel slicing method for XML documents. Essentially, given an XML document (which is valid w.r.t. some DTD), we produce a new XML document (a slice) that contains the relevant information in the original XML document according to some criterion. Furthermore, we also output a new DTD such that the computed slice is valid w.r.t. this DTD. A prototype implementation of the XML slicer has been undertaken.
37459114
Cluster Analysis of Named Entities
This paper presents a statistics-based and language independent unsupervised approach for clustering possible named entities. We describe and motivate the features and statistical filters used by our clustering process. Using the Model-Based Clustering Analysis software we obtained different clusters of named entities. The method was applied to Bulgarian and English. For some clusters, precision is close to 100%; this helps human validation and saves time. Other clusters still need further refinement.
14315671
Implementing distributed shared memory on top of MPI: the DSMPI library
Distributed shared memory has been recognized as an alternative programming model to exploit the parallelism in distributed memory systems since it provides a higher level of abstraction than simple message passing. DSM combines the simple programming model of shared-memory with the scalability of distributed memory machines. This paper presents DSMPI, a parallel library that runs atop of MPI and provides a distributed shared memory abstraction. It provides an easy-to-use programming interface, is flexible, portable and supports heterogeneity. Moreover, it supports different coherence protocols and models of consistency. We present some performance results taken in a network of workstations and in a Cray T3D which show that DSMPI can be competitive with MPI for some applications.
568204
Selecting Landmark Points for Sparse Manifold Learning
There has been a surge of interest in learning non-linear manifold models to approximate high-dimensional data. Both for computational complexity reasons and for generalization capability, sparsity is a desired feature in such models. This usually means dimensionality reduction, which naturally implies estimating the intrinsic dimension, but it can also mean selecting a subset of the data to use as landmarks, which is especially important because many existing algorithms have quadratic complexity in the number of observations. This paper presents an algorithm for selecting landmarks, based on LASSO regression, which is well known to favor sparse approximations because it uses regularization with an l1 norm. As an added benefit, a continuous manifold parameterization, based on the landmarks, is also found. Experimental results with synthetic and real data illustrate the algorithm.
14990773
Reset-Driven Fault Tolerance
A common approach in embedded systems to achieve fault-tolerance is to reboot the computer whenever some non-permanent error is detected. All the system code and data are recreated from scratch, and a previously established checkpoint, hopefully not corrupted, is used to restart the application data. The confidence is thus restored on the activity of the computer. The idea explored in this paper is that of unconditionally resetting the computer in each control frame (the classic read sensors → calculate control action → update actuators cycle). A stable-storage based in RAM is used to preserve the system's state between consecutive cleanups and a standard watchdog timer guarantees that a reset is forced whenever an error crashes the system. We have evaluated this approach by using fault-injection in the controller of a standard temperature control system. The experimental observations show that the Reset-Driven Fault Tolerance is a very simple yet effective technique to improve reliability at an extremely low cost since it is a conceptually simple, software only solution with the advantage of being application independent.
9570610
Towards Manageable Mobile Agent Infrastructures
This paper addresses the problem of managing distributed mobile agent infrastructures. First, the weaknesses of current mobile agent implementations will be discussed and identified from the manageability viewpoint. The solutions devised and experimented in order to alleviate these weaknesses in our own agent platform will then be presented. These solutions are generic and could easily be applied to the majority of existing mobile agent implementations. The paper will finish with the discussion of a new approach we are following in the M&M Project, based on a rather different architecture that significantly reduces the manageability requirements.