IBM

About: IBM is a company organization based out in Armonk, New York, United States. It is known for research contribution in the topics: Layer (electronics) & Signal. The organization has 134567 authors who have published 253905 publications receiving 7458795 citations. The organization is also known as: International Business Machines Corporation & Big Blue.

Continuously adaptive continuous queries over streams

Abstract: We present a continuously adaptive, continuous query (CACQ) implementation based on the eddy query processing framework We show that our design provides significant performance benefits over existing approaches to evaluating continuous queries, not only because of its adaptivity, but also because of the aggressive cross-query sharing of work and space that it enables By breaking the abstraction of shared relational algebra expressions, our Telegraph CACQ implementation is able to share physical operators --- both selections and join state --- at a very fine grain We augment these features with a grouped-filter index to simultaneously evaluate multiple selection predicates We include measurements of the performance of our core system, along with a comparison to existing continuous query approaches

Shape transition in growth of strained islands: Spontaneous formation of quantum wires.

Abstract: Strained epitaxial layers tend initially to grow as dislocation-free islands Here we show that such islands, as they increase in size, may undergo a shape transition Below a critical size, islands have a compact, symmetric shape But at larger sizes, they adopt a long thin shape, which allows better elastic relaxation of the island's stress We have observed such elongated islands, with aspect ratios greater than 50:1, in low energy electron microscopy studies of growth of Ag on Si (001) These islands represent a novel approach to the fabrication of «quantum wires»

Provably secure session key distribution: the three party case

Abstract: We study session key distribution in the three-party setting of Needham and Schroeder. (This is the trust model assumed by the popular Kerberos authentication system.) Such protocols are basic building blocks for contemporary distributed systems—yet the underlying problem has, up until now, lacked a definition or provably-good solution. One consequence is that incorrect protocols have proliferated. This paper provides the first treatment of this problem in the complexitytheoretic framework of modern cryptography. We present a definition, protocol, and a proof that the protocol satisfies the definition, assuming the (minimal) assumption of a pseudorandom function. When this assumption is appropriately instantiated, our protocols are simple and efficient. Abstract appearing in Proceedings of the 27th ACM Symposium on the Theory of Computing, May 1995.

A universal data compression system

Abstract: A universal data compression algorithm is described which is capable of compressing long strings generated by a "finitely generated" source, with a near optimum per symbol length without prior knowledge of the source. This class of sources may be viewed as a generalization of Markov sources to random fields. Moreover, the algorithm does not require a working storage much larger than that needed to describe the source generating parameters.