El Padre Rafael Landívar, S. J.

PADRE for COWs

Earlier work with the Parallel Document Retrieval Engine was oriented toward parallel machines such as the AP1000, characterised by many nodes, few disks, small memory per node (by current standards), single-user operation and high communication performance, relative to node computational power. Present generation parallel machines are much more like clusters of workstations (COWs). There are t...

PADRE : A Protocol for Asymmetric Duplex REdundancy

Safety and availability are issues of major importance in many critical systems. Ensuring simultaneously both attributes is sometimes difficult. Indeed, the introduction of redundancy to increase the overall system availability can lead to safety problems that would not otherwise exist. In this paper, we present a protocol for duplex redundancy management in critical systems that aims to increa...

Volker Kaibel and Rafael Mechtel

We introduce revlex-initial 0/1-polytopes as the convex hulls of reverse-lexicographically initial subsets of 0/1-vectors. These polytopes are special knapsack-polytopes. It turns out that they have remarkable extremal properties. In particular, we use these polytopes in order to prove that the minimum numbers gnfac(d, n) of facets and the minimum average degree gavdeg(d, n) of the graph of a d...

Rafael Lorente de No, 1946

PADRE | A Parallel Document Retrieval Engine

Developments in text retrieval on the AP1000 since last year's PCW are reported. The software, now called PADRE, has been entered in the competition associated with the 1994 Text Retrieval Conference (TREC-3). PADRE is now capable of document relevance estimation and ranking, and supports data loading from and dumping to the Fujitsu Local Filesystem. A new load balancing operation has been devi...