pinecone/core-2020-05-10-deduplication huggingface dataset:
Multi-party computation with omnipresent adversary

Secure multi-party computation (MPC) protocols enable a set of n mutually distrusting participants P 1, ..., P n , each with their own private input x i , to compute a function Y = F(x 1, ..., x n ), such that at the end of the protocol, all participants learn the correct value of Y, while secrecy of the private inputs is maintained. Classical results in the unconditionally secure MPC indicate that in the presence of an active adversary, every function can be computed if and only if the number of corrupted participants, t a , is smaller than n/3. Relaxing the requirement of perfect secrecy and utilizing broadcast channels, one can improve this bound to t a  < n/2.\ud
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All existing MPC protocols assume that uncorrupted participants are truly honest, i.e., they are not even curious in learning other participant secret inputs. Based on this assumption, some MPC protocols are designed in such a way that after elimination of all misbehaving participants, the remaining ones learn all information in the system. This is not consistent with maintaining privacy of the participant inputs. Furthermore, an improvement of the classical results given by Fitzi, Hirt, and Maurer indicates that in addition to t a actively corrupted participants, the adversary may simultaneously corrupt some participants passively. This is in contrast to the assumption that participants who are not corrupted by an active adversary are truly honest.\ud
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This paper examines the privacy of MPC protocols, and introduces the notion of an omnipresent adversary, which cannot be eliminated from the protocol. The omnipresent adversary can be either a passive, an active or a mixed one. We assume that up to a minority of participants who are not corrupted by an active adversary can be corrupted passively, with the restriction that at any time, the number of corrupted participants does not exceed a predetermined threshold. We will also show that the existence of a t-resilient protocol for a group of n participants, implies the existence of a t’-private protocol for a group of n′ participants. That is, the elimination of misbehaving participants from a t-resilient protocol leads to the decomposition of the protocol.\ud
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Our adversary model stipulates that a MPC protocol never operates with a set of truly honest participants (which is a more realistic scenario). Therefore, privacy of all participants who properly follow the protocol will be maintained. We present a novel disqualification protocol to avoid a loss of privacy of participants who properly follow the protocol
Distributed public-key cryptography from weak secrets

We introduce the notion of distributed password-based public-key cryptography, where a virtual high-entropy private key is implicitly defined as a concatenation of low-entropy passwords held in separate locations. The users can jointly perform private-key operations by exchanging messages over an arbitrary channel, based on their respective passwords, without ever sharing their passwords or reconstituting the key.\ud
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Focusing on the case of ElGamal encryption as an example, we start by formally defining ideal functionalities for distributed public-key generation and virtual private-key computation in the UC model. We then construct efficient protocols that securely realize them in either the RO model (for efficiency) or the CRS model (for elegance).\ud
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We conclude by showing that our distributed protocols generalize to a broad class of “discrete-log”-based public-key cryptosystems, which notably includes identity-based encryption. This opens the door to a powerful extension of IBE with a virtual PKG made of a group of people, each one memorizing a small portion of the master key
Negotiation of network security policy by means of agents

Proceeding of: 7th International Conference on Practical Applications of Agents and Multi-Agent Systems, 2009 (PAAMS 2009, 25-27 March 2009, Salamanca, SpainNowadays many intranets are deployed without enforcing any network security policy and just relying on security technologies such as firewalls or antivirus. In addition, the number and type of network entities are no longer fixed. Typically, laptops, PDAs or mobile phones need to have access to network resources occasionally. Therefore, it is important to design flexible systems that allow an easy administration of connectivity without compromising security. This article shows how software agents may provide secure configurations to a computer network in a distributed, autonomous and dynamic manner. Thus, here we describe the system architecture of a prototype, the negotiation protocol it uses and how it works in a sample scenario.Publicad
From monomorphic to polymorphic well-typings and beyond

Type information has many applications; it can e.g. be used 
in optimized compilation, termination analysis and error detection. How- 
ever, logic programs are typically untyped. A well-typed program has the 
property that it behaves identically on well-typed goals with or without 
type checking. Hence the automatic inference of a well-typing is worth- 
while. Existing inferences are either cheap and inaccurate, or accurate 
and expensive. By giving up the requirement that all calls to a predicate 
have types that are instances of a unique polymorphic type but instead 
allowing multiple polymorphic typings for the same predicate, we ob- 
tain a novel strongly-connected-component-based analysis that provides 
a good compromise between accuracy and computational cost.status: publishe
On the role of magnetic reconnection in jet/accretion disk systems

The most accepted model for jet production is based on the
magneto-centrifugal acceleration out off an accretion disk that surrounds the
central source (Blandford & Payne, 1982). This scenario, however, does not
explain, e.g., the quasi-periodic ejection phenomena often observed in
different astrophysical jet classes. de Gouveia Dal Pino & Lazarian (2005)
(hereafter GDPL) have proposed that the large scale superluminal ejections
observed in microquasars during radio flare events could be produced by violent
magnetic reconnection (MR) episodes. Here, we extend this model to other
accretion disk systems, namely: active galactic nuclei (AGNs) and young stellar
objects (YSOs), and also discuss its role on jet heating and particle
acceleration.Comment: To be published in the IAU Highlights of Astronomy, Volume 15, XXVII
  IAU General Assembly, August 2009, Ian F. Corbett et al., eds., 201
Magnetohydrodynamic jets from different magnetic field configurations

Using axisymmetric MHD simulations we investigate how the overall jet
formation is affected by a variation in the disk magnetic flux profile and/or
the existence of a central stellar magnetosphere. Our simulations evolve from
an initial, hydrostatic equilibrium state in a force-free magnetic field
configuration. We find a unique relation between the collimation degree and the
disk wind magnetization power law exponent. The collimation degree decreases
for steeper disk magnetic field profiles. Highly collimated outflows resulting
from a flat profile tend to be unsteady. We further consider a magnetic field
superposed of a stellar dipole and a disk field in parallel or anti-parallel
alignment. Both stellar and disk wind may evolve in a pair of outflows,
however, a reasonably strong disk wind component is essential for jet
collimation. Strong flares may lead to a sudden change in mass flux by a factor
two. We hypothesize that such flares may eventually trigger jet knots.Comment: 5 pages, 4 figures; proceedings from conference: Protostellar Jets in
  Context, held in Rhodes, July 7-12, 200
Protostellar Jet and Outflow in the Collapsing Cloud Core

We investigate the driving mechanism of outflows and jets in star formation
process using resistive MHD nested grid simulations. We found two distinct
flows in the collapsing cloud core: Low-velocity outflows (sim 5 km/s) with a
wide opening angle, driven from the first adiabatic core, and high-velocity
jets (sim 50 km/s) with good collimation, driven from the protostar.
High-velocity jets are enclosed by low-velocity outflow. The difference in the
degree of collimation between the two flows is caused by the strength of the
magnetic field and configuration of the magnetic field lines. The magnetic
field around an adiabatic core is strong and has an hourglass configuration.
Therefore, the low-velocity outflow from the adiabatic core are driven mainly
by the magnetocentrifugal mechanism and guided by the hourglass-like field
lines. In contrast, the magnetic field around the protostar is weak and has a
straight configuration owing to Ohmic dissipation in the high-density gas
region. Therefore, high-velocity jet from the protostar are driven mainly by
the magnetic pressure gradient force and guided by straight field lines.
Differing depth of the gravitational potential between the adiabatic core and
the protostar cause the difference of the flow speed. Low-velocity outflows
correspond to the observed molecular outflows, while high-velocity jets
correspond to the observed optical jets. We suggest that the protostellar
outflow and the jet are driven by different cores (the first adiabatic core and
protostar), rather than that the outflow being entrained by the jet.Comment: To appear in the proceedings of the "Protostellar Jets in Context"
  conference held on the island of Rhodes, Greece (7-12 July 2008
Development of a real-time full-field range imaging system

This article describes the development of a full-field range imaging system employing a high frequency amplitude modulated light source and image sensor. Depth images are produced at video frame rates in which each pixel in the image represents distance from the sensor to objects in the scene. 
The various hardware subsystems are described as are the details about the firmware and software implementation for processing the images in real-time. The system is flexible in that precision can be traded off for decreased acquisition time. Results are reported to illustrate this versatility for both high-speed (reduced precision) and high-precision operating modes
Alignment-based Partitioning of Large-scale Ontologies

Ontology alignment is an important task for information integration systems that can make different resources, described by various and heterogeneous ontologies, interoperate. However very large ontologies have been built in some domains such as medicine or agronomy and the challenge now lays in scaling up alignment techniques that often perform complex tasks. In this paper, we propose two partitioning methods which have been designed to take the alignment objective into account in the partitioning process as soon as possible. These methods transform the two ontologies to be aligned into two sets of blocks of a limited size. Furthermore, the elements of the two ontologies that might be aligned are grouped in a minimal set of blocks and the comparison is then enacted upon these blocks. Results of experiments performed by the two methods on various pairs of ontologies are promising
Attention Mechanisms in the CHREST Cognitive Architecture

In: Proceedings of the Fifth International Workshop on Attention in Cognitive Systems, edited by Paletta, L.; Tsotsos, J.K.(Springer-Verlag) ???The original publication is available at www.springerlink.com???. Copyright Springer. DOI: 10.1007/978-3-642-00582-4_14In this paper, we describe the attention mechanisms in CHREST, a computational architecture of human visual expertise. CHREST organises information acquired by direct experience from the world in the form of chunks. These chunks are searched for, and verified, by a unique set of heuristics, comprising the attention mechanism. We explain how the attention mechanism combines bottom-up and top-down heuristics from internal and external sources of information. We describe some experimental evidence demonstrating the correspondence of CHREST???s perceptual mechanisms with those of human subjects. Finally, we discuss how visual attention can play an important role in actions carried out by human experts in domains such as chess
An interval-based inference of variant parametric types.

Variant parametric types represent the successful integration of subtype and parametric polymorphism to support a more flexible subtyping for Java like languages. A key feature that helps strengthen this integration is the use-site variance. Depending on how the fields are used, each variance denotes a covariant, a contravariant, an invariant or a bivariant subtyping. By annotating variance properties on each type argument to a parametric class, programmers can choose various desirable variance properties for each use of the parametric class. Although Java library classes have been successfully refactored to use variant parametric types, these mechanisms are often criticized, due to the difficulty of choosing appropriate variance annotations. Several algorithms have been proposed for automatically refactoring legacy Java code to use generic libraries, but none can support the full flexibility of the use-site variance-based subtyping. This paper addresses this difficulty by proposing a novel interval-based approach to inferring both the variance annotations and the type arguments. Each variant parametric type is regarded as an interval type with two type bounds, a lower bound for writing and an upper bound for reading. We propose a constraint-based inference algorithm that works on a per method basis, as a summary-based analysis
Formal foundation for pattern-based modelling

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-00593-0_19Proceedings of 12th International Conference, FASE 2009, Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2009, York, UK, March 22-29, 2009.We present a new visual and formal approach to the specification of patterns, supporting pattern analysis and pattern-based model completion. The approach is based on graphs, morphisms and operations from category theory and exploits triple graphs to annotate model elements with pattern roles. Novel in our proposal is the possibility of describing (nested) variable submodels, as well as inter-pattern synchronization across several diagrams (e.g. class and sequence diagrams for UML design patterns). We illustrate the approach on UML design patterns, and discuss its generality and applicability on different types of patterns, e.g. workflow patterns using Coloured Petri nets.Work supported by the Spanish Ministry of Science and Innovation, projects METEORIC (TIN 2008-02081) and MODUWEB (TIN 2006-09678). We thank the referees for their insightful and detailed comment
On the Expressive Power of Restriction and Priorities in CCS with replication

International audienceWe study the expressive power of restriction and its interplay with replication. We do this by considering several syntactic variants of CCS! (CCS with replication instead of recursion) which differ from each other in the use of restriction with respect to replication. We consider three syntactic variations of CCS! which do not allow the use of an unbounded number of restrictions: C1 is the fragment of CCS! not allowing restrictions under the scope of a replication. C2 is the restriction-free fragment of CCS!. The third variant is C3 which extends C1 with Phillips' priority guards. We show that the use of unboundedly many restrictions in CCS! is necessary for obtaining Turing expressiveness in the sense of Busi et al [8]. We do this by showing that there is no encoding of RAMs into C2 which preserves and reflects convergence. We also prove that up to failures equivalence, there is no encoding from CCS! into C1 nor from C1 into C2. As lemmata for the above results we prove that convergence is decidable for C1 and that language equivalence is decidable for CCS2. As corollary it follows that convergence is decidable for restriction-free CCS. Finally, we show the expressive power of priorities by providing an encoding of RAMs in C3
Realizability of Concurrent Recursive Programs

International audienceWe define and study an automata model of concurrent recursive programs. An automaton consists of a finite number of pushdown systems running in parallel and communicating via shared actions. Actually, we combine multi-stack visibly pushdown automata and Zielonka's asynchronous automata towards a model with an undecidable emptiness problem. However, a reasonable restriction allows us to lift Zielonka's Theorem to this recursive setting and permits a logical characterization in terms of a suitable monadic second-order logic. Building on results from Mazurkiewicz trace theory and work by La Torre, Madhusudan, and Parlato, we thus develop a framework for the specification, synthesis, and verification of concurrent recursive processes
A sparsity-based method to solve the permutation indeterminacy in frequency domain convolutive blind source separation

International audienceExisting methods for frequency-domain estimation of mixing filters in convolutive blind source separation (BSS) suffer from permutation and scaling indeterminacies in sub-bands. However, if the filters are assumed to be sparse in the time domain, it is shown in this paper that the l1-norm of the filter matrix increases as the sub-band coefficients are permuted. With this motivation, an algorithm is then presented which solves the source permutation indeterminacy, provided there is no scaling indeterminacy in sub-bands. The robustness of the algorithm to noise is also presented
Nonnegative network component analysis by linear programming for gene regulatory network reconstruction

LNCS v. 5441 is Proceedings of the 8th International Conference, ICA 2009We consider a systems biology problem of reconstructing gene regulatory network from time-course gene expression microarray data, a special blind source separation problem for which conventional methods cannot be applied. Network component analysis (NCA), which makes use of the structural information of the mixing matrix, is a tailored method for this specific blind source separation problem. In this paper, a new NCA method called nonnegative NCA (nnNCA) is proposed to take into account of the non-negativity constraint on the mixing matrix that is based on a reasonable biological assumption. The nnNCA problem is formulated as a linear programming problem which can be solved effectively. Simulation results on spectroscopy data and experimental results on time-course microarray data of yeast cell cycle demonstrate the effectiveness and anti-noise robustness of the proposed nnNCA method. © Springer-Verlag Berlin Heidelberg 2009.postprintThe 8th International Conference on Independent Component Analysis and Signal Separation (ICA 2009), Paraty, Brazil, 15-18 March 2009. In Lecture Notes in Computer Science, 2009, v. 5441, p. 395-40
Underdetermined instantaneous audio source separation via local Gaussian modeling

International audienceUnderdetermined source separation is often carried out by modeling time-frequency source coefficients via a fixed sparse prior. This approach fails when the number of active sources in one time-frequency bin is larger than the number of channels or when active sources lie on both sides of an inactive source. In this article, we partially address these issues by modeling time-frequency source coefficients via Gaussian priors with free variances. We study the resulting maximum likelihood criterion and derive a fast non-iterative optimization algorithm that finds the global minimum. We show that this algorithm outperforms state-of-the- art approaches over stereo instantaneous speech mixtures
Philosophical conceptions of information

???The original publication is available at www.springerlink.com??? Copyright Springer'I love information upon all subjects that come in my way, and especially upon those that are most important.' Thus boldly declares Euphranor, one of the defenders of Christian faith in Berkley???s Alciphron (Berkeley, (1732), Dialogue 1, Section 5, Paragraph 6/10). Evidently, information has been an object of philosophical desire for some time, well before the computer revolution, Internet or the dot.com pandemonium (see for example Dunn (2001) and Adams (2003)). Yet what does Euphranor love, exactly? What is information? The question has received many answers in different fields. Unsurprisingly, several surveys do not even converge on a single, unified definition of information (see for example Braman 1989, Losee (1997), Machlup and Mansfield (1983), Debons and Cameron (1975), Larson and Debons (1983))
Finding irredundant contained rewritings of tree pattern queries using views

Contained rewriting and maximal contained rewriting of tree pattern queries using views have been studied recently for the class of tree patterns involving /, //, and []. Given query Q and view V, it has been shown that a contained rewriting of Q using V can be obtained by finding a useful embedding of Q in V. However, for the same Q and V, there may be many useful embeddings and thus many contained rewritings. Some of the useful embeddings may be redundant in that the rewritings obtained from them are contained in those obtained from other useful embeddings. Redundant useful embeddings are useless and they waste computational resource. Thus it becomes important to identify and remove them. In this paper, we show that the criteria for identifying redundant useful embeddings given in a previous work are neither sufficient nor necessary. We then present some useful observations on the containment relationship of rewritings, and based on which, a heuristic algorithm for removing redundant useful embeddings. We demonstrate the efficiency of our algorithm using examples.Griffith Sciences, School of Information and Communication TechnologyFull Tex
Test input generation for programs with pointers

Acknowledgement: This research is partially funded by the Interuniversity Attraction Poles Programme Belgian State, Belgian Science Policy, and by the Research Fund K.U.Leuven.Software testing is an essential process to improve software quality in practice. Researchers have proposed several techniques to automate parts of this process. In particular, symbolic execution can be used to automatically generate a set of test inputs that achieves high
code coverage. 

However, most state-of-the-art symbolic execution approaches cannot directly handle programs whose inputs are pointers, as is often the case
for C programs. Automatically generating test inputs for pointer manipulating code such as a linked list or balanced tree implementation remains a challenge. Eagerly enumerating all possible heap shapes forfeits
the advantages of symbolic execution. Alternatively, for a tester, writing assumptions to express the disjointness of memory regions addressed by input pointers is a tedious and labor-intensive task.

This paper proposes a novel solution for this problem: by exploiting type information, disjointness constraints that characterize permissible configurations of typed pointers in byte-addressable memory can be automatically
generated. As a result, the constraint solver can automatically generate relevant heap shapes for the program under test. We report on our experience with an implementation of this approach in Pex, a dynamic
symbolic execution framework for .NET.We examine two different symbolic representations for typed memory, and we discuss the impact of various optimizations.status: publishe