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38
Braided Hopf algebras over non abelian finite groups
 Acad. Nac. Ciencias (Córdoba
"... Abstract. In the last years a new theory of Hopf algebras has begun to be developed: that of Hopf algebras in braided categories, or, briefly, braided Hopf algebras. This is a survey of general aspects of the theory with emphasis in H HYD, the Yetter–Drinfeld category over H, where H is the group al ..."
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Cited by 40 (12 self)
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Abstract. In the last years a new theory of Hopf algebras has begun to be developed: that of Hopf algebras in braided categories, or, briefly, braided Hopf algebras. This is a survey of general aspects of the theory with emphasis in H HYD, the Yetter–Drinfeld category over H, where H is the group algebra of a non abelian finite group Γ. We discuss a special class of braided graded Hopf algebras from different points of view following Lusztig, Nichols and Schauenburg. We present some finite dimensional examples arising in an unpublished work by Milinski and Schneider. Sinopsis. En los últimos años comenzó a ser desarrollada una nueva teoría de álgebras de Hopf en categorías trenzadas, o brevemente, álgebras de Hopf trenzadas. Presentamos aquí aspectos generales de la teoría con énfasis en H HYD, la categoría de Yetter–Drinfeld sobre H, donde H es el álgebra de grupo de un grupo finito no abeliano Γ. Discutimos una clase especial de álgebras de Hopf trenzadas graduadas desde diferentes puntos de vista, siguiendo a Lusztig, Nichols y Schauenburg. Presentamos algunos ejemplos de dimensión finita que aparecen en un trabajo inédito de Milinski y Schneider. 0. Introduction and notations 0.1. Introduction.
Peakword condensation and submodule lattices: An application of the MeatAxe
 J. Symb. Comp
, 1994
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Sooner is safer than later
 Information Processing Letters
, 1992
"... Abstract. It has been observed repeatedly that the standard safetyliveness classi cation for properties of reactive systems does not t for realtime properties. This is because the implicit \liveness " of time shifts the spectrum towards the safety side. While, for example, response  that ..."
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Cited by 25 (8 self)
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Abstract. It has been observed repeatedly that the standard safetyliveness classi cation for properties of reactive systems does not t for realtime properties. This is because the implicit \liveness &quot; of time shifts the spectrum towards the safety side. While, for example, response  that \something good &quot; will happen eventually  is a classical liveness property, bounded response  that \something good &quot; will happen soon, within a certain amount of time  has many characteristics of safety. Weaccount for this phenomenon formally by de ning safety and liveness relative to a given condition, such as the progress of time.
On finitedimensional semisimple and cosemisimple Hopf algebras in positive characteristic
 Internat. Math. Res. Notices
, 1998
"... Recently, important progress has been made in the study of finitedimensional semisimple Hopf algebras over a field of characteristic zero (see [Mo] and references therein). Yet, very little is known over a field k of positive characteristic. In this paper we first prove in Theorem 2.1 that any fini ..."
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Recently, important progress has been made in the study of finitedimensional semisimple Hopf algebras over a field of characteristic zero (see [Mo] and references therein). Yet, very little is known over a field k of positive characteristic. In this paper we first prove in Theorem 2.1 that any finitedimensional semisimple and
Lamport on Mutual Exclusion: 27 Years of Planting Seeds
 In 20th ACM Symposium on Principles of Distributed Computing
, 2001
"... Mutual exclusion is a topic that Leslie Lamport has returned to many times throughout his career. This article, which is being written in celebration of Lamport's sixtieth birthday, is an attempt to survey some of his many contributions to research on this topic. ..."
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Mutual exclusion is a topic that Leslie Lamport has returned to many times throughout his career. This article, which is being written in celebration of Lamport's sixtieth birthday, is an attempt to survey some of his many contributions to research on this topic.
An Analysis of Total Correctness Refinement Models for Partial Relation Semantics II
, 2000
"... This is the second in a series of papers devoted to the thorough investigation of (total correctness) refinement based on an underlying partial relational model. This paper investigates operation refinement and datarefinement based on a weakest precondition interpretation for specifications whose s ..."
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Cited by 9 (7 self)
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This is the second in a series of papers devoted to the thorough investigation of (total correctness) refinement based on an underlying partial relational model. This paper investigates operation refinement and datarefinement based on a weakest precondition interpretation for specifications whose semantics is given by partial relations. We consider three refinement theories based on a weakest precondition interpretation for partial relation semantics: an operation refinement theory, and theories characterising datarefinement with forward and backward simulations. We show that each of these is equivalent to a (corresponding) modeltheoretic refinement theory that is based on the standard approach involving relational completion operators. In addition, we demonstrate that each of the three is also equivalent to a (corresponding) prooftheoretic notion of refinement.
BAR Gossip
"... We present the first peertopeer data streaming application that guarantees predictable throughput and low latency in the BAR (Byzantine/Altruistic/Rational) model, in which nonaltruistic nodes can behave in ways that are selfserving (rational) or arbitrarily malicious (Byzantine). At the core of ..."
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Cited by 8 (0 self)
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We present the first peertopeer data streaming application that guarantees predictable throughput and low latency in the BAR (Byzantine/Altruistic/Rational) model, in which nonaltruistic nodes can behave in ways that are selfserving (rational) or arbitrarily malicious (Byzantine). At the core of our solution is a BARtolerant version of gossip, a wellknown technique for scalable and reliable data dissemination. BAR Gossip relies on verifiable pseudorandom partner selection to eliminate nondeterminism that can be used to game the system while maintaining the robustness and rapid convergence of traditional gossip. A novel fair enough exchange primitive entices cooperation among selfish nodes on short timescales, avoiding the need for longterm node reputations. Our initial experience provides evidence for BAR Gossip’s robustness. Our BARtolerant streaming application provides over 99 % convergence for broadcast updates when all clients are selfish but not colluding, and over 95 % convergence when up to 40 % of clients collude while the rest follow the protocol. BAR Gossip also performs well when the client population consists of both selfish and Byzantine nodes, achieving over 93 % convergence even when 20 % of the nodes are Byzantine. 1
O.: Body Image Formation Hypotheses Based On Corona Discharge, The Third
 Dallas International Conference on the Shroud of
, 2005
"... Lattarulo and O. Scheuermann. It contains hypotheses, experimental results and comments; however, some questions which came up during the discussions at the SSG (Shroud Science Group) level, led the author to write the present paper. After a presentation of the main points regarding CD (Corona Disch ..."
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Cited by 5 (3 self)
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Lattarulo and O. Scheuermann. It contains hypotheses, experimental results and comments; however, some questions which came up during the discussions at the SSG (Shroud Science Group) level, led the author to write the present paper. After a presentation of the main points regarding CD (Corona Discharge), and the definition of the hypotheses regarding the assumed model, some new evidence is presented and discussed here, such as the exsiccation of limited parts of linen fibers. The paper then explains different points raised by the SSG, such as the radiation direction, the 3D effects of radiation and its mathematical representation, the image resolution, the double draping configurations of the TS, and the color on the linen fibers. The experimental results obtained to support the hypothesized mechanism show no appreciable chemicalphysical differences from the image features of the TS. These results confirm that the proposed CD mechanism could have been involve d in the TS body image formation. 1.
On the Graphs of HoffmanSingleton and HigmanSims
"... We propose a new elementary definition of the HigmanSims graph in which the 100 vertices are parametrised with Z 4 5 and adjacencies are described by linear and quadratic equations. This definition extends Robertson's pentagonpentagram definition of the Ho#manSingleton graph and is obta ..."
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We propose a new elementary definition of the HigmanSims graph in which the 100 vertices are parametrised with Z 4 5 and adjacencies are described by linear and quadratic equations. This definition extends Robertson's pentagonpentagram definition of the Ho#manSingleton graph and is obtained by studying maximum cocliques of the Ho#manSingleton graph in Robertson's parametrisation. The new description is used to count the 704 Ho#manSingleton subgraphs in the HigmanSims graph, and to describe the two orbits of the simple group HS on them, including a description of the doubly transitive action of HS within the HigmanSims graph. Numerous geometric connections are pointed out. As a byproduct we also have a new construction of the Steiner system S(3, 6, 22).
Dynamic Sparsing in Stiff Extrapolation Methods
, 1992
"... Based on a simple stability analysis for the semiimplicit Euler discretization a new dynamic sparsing procedure is derived. This procedure automatically eliminates "small" elements of the Jacobian matrix. As a consequence, the amount of work needed to handle the linear algebra within a s ..."
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Based on a simple stability analysis for the semiimplicit Euler discretization a new dynamic sparsing procedure is derived. This procedure automatically eliminates "small" elements of the Jacobian matrix. As a consequence, the amount of work needed to handle the linear algebra within a semiimplicit extrapolation integrator can be reduced drastically. Within the course of integration the sparsing criterion, which decides what "small" means, is dynamically adapted to ensure stability of the discretization scheme. Thus, stepsize restrictions due to instability can be avoided. Numerical experiments for quite different problems show robustness and efficiency of this dynamic sparsing technique. The techniques developed here in the context of stiff extrapolation integrators can, in principle, be applied to Wmethods, where exact Jacobians may be replaced by "sufficiently good" approximations.