Embedding cube-connected cycles graphs into faulty hypercubes

We consider the problem of embedding a cube-connected cycles graph (CCC) into a hypercube with edge faults. Our main result is an algorithm that, given a list of faulty edges, computes an embedding of the CCC that spans all of the nodes and avoids all of the faulty edges. The algorithm has optimal running time and tolerates the maximum number of faults (in a worst-case setting). Because ascend-descend algorithms can be implemented efficiently on a CCC, this embedding enables the implementation of ascend-descend algorithms, such as bitonic sort, on hypercubes with edge faults. We also present a number of related results, including an algorithm for embedding a CCC into a hypercube with edge and node faults and an algorithm for embedding a spanning torus into a hypercube with edge faults

Tolerating faults in hypercubes using subcube partitioning

We examine the issue of running algorithms on a hypercube which has both node and edge faults, and we assume a worst case distribution of the faults. We prove that for any constant c, an n-dimensional hypercube (n-cube) with n^c faulty components contains a fault-free subgraph that can implement a large class of hypercube algorithms with only a constant factor slowdown. In addition, our approach yields practical implementations for small numbers of faults. For example, we show that any regular algorithm can be implemented on an n-cube that has at most n-1 faults with slowdowns of at most 2 for computation and at most 4 for communication. To the best of our knowledge this is the first result showing that an n-cube can tolerate more than O(n) arbitrarily placed faults with a constant factor slowdown

Transitive Reduction in Parallel via Branchings

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryJoint Services Electronics Program / N00014-84-C-0149International Computer Science InstituteNational Science Foundation / CCR-8411954 and DCR-8605962Office of Naval Research / N00014-87-K-046

Using XForms to Simplify Web Programming

The difficulty of developing and deploying commercial web applications increases as the number of technologies they use increases and as the interactions between these technologies become more complex. This paper describes a way to avoid this increasing complexity by re-examining the basic requirements of web applications. Our approach is to first separate client concerns from server concerns, and then to reduce the interaction between client and server to its most elemental: parameter passing. We define a simplified programming model for form-based web applications and we use XForms and a subset of J2EE as enabling technologies. We describe our implementation of an MVC-based application builder for this model, which automatically generates the code needed to marshal input and output data between clients and servers. This marshalling uses type checking and other forms of validation on both clients and servers. We also show how our programming model and application builder support the customization of web applications for different execution targets, including, for example, different client devices

Pegboard: A Framework for Developing Mobile Applications

@ us.ibm.com dig @ uiuc.edu san @ zurich.ibm.com Tool support for mobile application development can significantly improve programmer productivity and software quality. Pegboard is a novel tooling framework that extends the Eclipse integrated development environment to support the development of mobile distributed applications. Its extensible design supports multiple application models and the orchestration of external tooling components throughout the development cycle. In this paper we describe Pegboard’s architecture and implementation, and show how it improves the development experience through organization, visualization, simplification and guidance. We also discuss insights gained from interviewing software developers, including early users of Pegboard