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Laboratory and Siemens Corp. **Also supported by an IBM graduate fellowship. Faulttolerant Waitfree Shared Objects*
, 1992
"... A concurrent system consists of processes communicating via shared objects, such as shared variables, queues, etc. The concept of wait.freedom was introduced to cope with proce3J failures: each process that accesses a waitfree object is guaranteed to get a response even if all the other processes c ..."
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A concurrent system consists of processes communicating via shared objects, such as shared variables, queues, etc. The concept of wait.freedom was introduced to cope with proce3J failures: each process that accesses a waitfree object is guaranteed to get a response even if all the other processes crash. But what if these waitfree objects themselves fail? For example, if a waitfree object "crashes", all the processes that access that object are prevented from making progress. In this paper, we introduce the concept of fault.tolerant waitflee objects, and study the problem of implementing them. We give a universal method to construct faulttolerant waRfree objects, for all types of "responsive " failures (including one in which faulty objects may "lie"). In sharp contrast, we prove that many common and interesting object types (such as queues, sets, and test&set) have no faulttolerant waitfree implementations even under the most benign of the "nonresponsive " types of failure. We also introduce several concepts and techniques that are central to the design of faulttolerant concurrent systems: the concepts of selfimplementation and graceful degradation, and techniques to automatically increase the faulttolerance of implementations. We prove matching lower bounds on the resource complexity of most of our algorithms.
* This work was supported by National Science Foundation grants CCR8919635 and CCR9410706 and by an IBM Graduate Fellowship.
 IEEE Transactions on Computers
, 1996
"... To exploit instruction level parallelism, it is important not only to execute multiple memory references per cycle, but also to reorder memory references, especially to execute loads before stores that precede them in the sequential instruction stream. To guarantee correctness of execution in such s ..."
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To exploit instruction level parallelism, it is important not only to execute multiple memory references per cycle, but also to reorder memory references, especially to execute loads before stores that precede them in the sequential instruction stream. To guarantee correctness of execution in such situations, memory reference addresses have to be disambiguated. This paper presents a novel hardware mechanism, called an Address Resolution Buffer (ARB), for performing dynamic reordering of memory references. The ARB supports the following features: (i) dynamic memory disambiguation in a decentralized manner, (ii) multiple memory references per cycle, (iii) outoforder execution of memory references, (iv) unresolved loads and stores, (v) speculative loads and stores, and (vi) memory renaming. The paper presents the results of a simulation study that we conducted to verify the efficacy of the ARB for a superscalar processor. The paper also shows the ARB's application in a multiscalar proce...
Plans As Complex Mental Attitudes
 Intentions in Communication
, 1990
"... this paper was supported by a gift from the Systems Development Foundation. The research was done as part of my doctoral thesis [19], which was supported by a gift from the Systems Development Foundation, by an IBM Graduate Fellowship, by the Defense Advanced Research Projects Agency under Contract ..."
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Cited by 259 (3 self)
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this paper was supported by a gift from the Systems Development Foundation. The research was done as part of my doctoral thesis [19], which was supported by a gift from the Systems Development Foundation, by an IBM Graduate Fellowship, by the Defense Advanced Research Projects Agency under Contract
SelfTesting/Correcting with Applications to Numerical Problems
, 1990
"... Suppose someone gives us an extremely fast program P that we can call as a black box to compute a function f . Should we trust that P works correctly? A selftesting/correcting pair allows us to: (1) estimate the probability that P (x) 6= f(x) when x is randomly chosen; (2) on any input x, compute ..."
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Cited by 361 (27 self)
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, California 94704 z Computer Science Division, U.C. Berkeley, Berkeley, California 94720, Supported by an IBM Graduate Fellowship and NSF Grant No. CCR 8813632. the original running time of P . We present general techniques for constructing simple to program selftesting /correcting pairs for a variety
Minimax Programs
 University of California Press
, 1997
"... We introduce an optimization problem called a minimax program that is similar to a linear program, except that the addition operator is replaced in the constraint equations by the maximum operator. We clarify the relation of this problem to some betterknown problems. We identify an interesting spec ..."
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Cited by 482 (5 self)
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highly effective algorithms for solution of various classes of linear programs. Linear programming represents one of the major achievements of the operations research and mathematical programming community. Supported in part by a National Science Foundation Graduate Fellowship. In this paper we
Publickey Cryptosystems Provably Secure against Chosen Ciphertext Attacks
 In Proc. of the 22nd STOC
, 1995
"... We show how to construct a publickey cryptosystem (as originally defined by Diffie and Hellman) secure against chosen ciphertext attacks, given a publickey cryptosystem secure against passive eavesdropping and a noninteractive zeroknowledge proof system in the shared string model. No such secure ..."
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Cited by 284 (19 self)
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and Rose Goldman Career Development Chair, Dept. of Applied Mathematics and Computer Science, Weizmann Institute of Science, Rehovot 76100, Israel. Work performed while at the IBM Almaden Research Center. Research supported by an Alon Fellowship and a grant from the Israel Science Foundation administered
Graduate Fellowship.
, 1999
"... Twenty years ago, Calabi and Yau each proved that a complete noncompact Riemannian manifold with nonnegative Ricci curvature must have at least linear volume growth [Yau]. This was proven by studying the Busemann function, b = bγ, associated with a ray, γ, b(x) = lim (R − d(x,γ(R)). R→∞ In [So2], t ..."
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Twenty years ago, Calabi and Yau each proved that a complete noncompact Riemannian manifold with nonnegative Ricci curvature must have at least linear volume growth [Yau]. This was proven by studying the Busemann function, b = bγ, associated with a ray, γ, b(x) = lim (R − d(x,γ(R)). R→∞ In [So2], the author proved that if such a manifold has linear volume growth then its Busemann functions are proper. The simplest examples of manifolds with linear volume growth are the metric product manifolds, X × RI, whose cross sections, X × {r}, are level sets of the Busemann functions. In this paper we prove that a complete noncompact manifold with nonnegative Ricci curvature and linear volume growth must be close to being such a metric product manifold asymptotically [Theorem 34]. That is, as r → ∞, the set b −1 ([r,r +L]) becomes close to b −1 (r) ×[r,r +L] in the GromovHausdorff topology where the closeness depends linearly on diam(b −1 (r)). See Section 2. The proof involves a careful analysis of the Busemann function using the recentlydeveloped CheegerColding Almost Rigidity Theory [ChCo]. We also use this method to prove the following theorem. Theorem 1 If M n is a manifold with nonnegative Ricci curvature and linear volume growth, then it has sublinear diameter growth, diam(b lim R→∞ −1 (R))
Nonreflecting Boundary Conditions For Time Dependent Scattering
 SIAM J. Appl. Math
, 1996
"... An exact nonreflecting boundary condition was derived previously for use with the time dependent wave equation in three space dimensions [1]. Here it is shown how to combine that boundary condition with finite difference methods and finite element methods. Uniqueness of the solution is proved, stabi ..."
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Cited by 55 (2 self)
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, stability issues are discussed, and improvements are proposed for numerical computation. Numerical examples are presented which demonstrate the improvement in accuracy over standard methods. 1 Supported by an IBM graduate fellowship (grote@cims.nyu.edu). 2 Supported in part by AFOSR, NSF, and ONR (keller
Learning Featurebased Semantics with Simple Recurrent Networks
, 1990
"... The paper investigates the possibilities for using simple recurrent networks as transducers which map sequential natural language input into nonsequential featurebased semantics. The networks perform well on sentences containing a single main predicate (encoded by transitive verbs or prepositions) ..."
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Cited by 23 (4 self)
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The author is supported by an IBM Graduate Fellowship. 1 Introduction Since their introduction by Elman [...
Tree Matching with Recursive Distributed Representations
, 1992
"... We present an approach to the structure unification problem using distributed representations of hierarchical objects. Binary trees are encoded using the recursive autoassociation method (RAAM), and a unification network is trained to perform the tree matching operation on the RAAM representations. ..."
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Cited by 22 (0 self)
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@icsi.berkeley.edu. Research supported by an IBM Graduate Fellowship and by the Internati...
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