On Optimal Trees for Irregular Gather and Scatter Collectives

On Optimal Trees for Irregular Gather and Scatter Collectives

This paper studies the complexity of finding costoptimal communication trees for rooted, irregular gather and scatter collective communication operations in fully connected, one-ported communication networks under a linear, but not necessarily homogeneous transmission cost model. In the irregular gather and scatter problems, different processors may specify data blocks of possibly different siz...

Two Algorithms of Irregular Scatter/Gather Operations for Heterogeneous Platforms

The Impact of Hardware Gather/Scatter on Sparse Gaussian Elimination

Recent vector supercomputers provide vector memory access to "randomly" indexed vectors, whereas early vector supercomputers required contiguously or regularly indexed vectors. This additional capability, known as "hardware gather/scatter," can be used to great effect in general sparse Gaussian elimination. In this note we present some examples that show the impact of this change in hardware on...

Cluster Labeling for Multilingual Scatter/Gather Using Comparable Corpora

Scatter/Gather systems are increasingly becoming useful in browsing document corpora. Usability of the present-day systems are restricted to monolingual corpora, and their methods for clustering and labeling do not easily extend to the multilingual setting, especially in the absence of dictionaries/machine translation. In this paper, we study the cluster labeling problem for multilingual corpor...

A Fast Online Clustering Algorithm for Scatter/Gather Browsing

We present a fast online clustering algorithm which has linear worst-case time complexity and constant running time average for the well-known online visually oriented browsing modeling called Scatter/Gather browsing (Cutting, Karger, Pedersen, and Tukey 1992). Our experiment shows when running on a single processor, this fast online clustering algorithm is few hundred times faster than the par...