arXiv
(422,153 recursos)
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Mostrando recursos 61 - 80 de 9,277
61.
CDTP Chain Distributed Transfer Protocol - Vagner, Shmuel
The rapid growth of the internet in general and of bandwidth capacity at
internet clients in particular poses increasing computation and bandwidth
demands on internet servers. Internet access technologies like ADSL [DSL],
Cable Modem and Wireless modem allow internet clients to access the internet
with orders of magnitude more bandwidth than using traditional modems. We
present CDTP a distributed transfer protocol that allows clients to cooperate
and therefore remove the strain from the internet server thus achieving much
better performance than traditional transfer protocols (e.g. FTP [FTP]). The
CDTP server and client tools are presented also as well as results of
experiments. Finally a bandwidth measurement technique is presented....
62.
A Distributed Economics-based Infrastructure for Utility Computing - Treaster, Michael; Kiyanclar, Nadir; Koenig, Gregory A.; Yurcik, William
Existing attempts at utility computing revolve around two approaches. The
first consists of proprietary solutions involving renting time on dedicated
utility computing machines. The second requires the use of heavy, monolithic
applications that are difficult to deploy, maintain, and use.
We propose a distributed, community-oriented approach to utility computing.
Our approach provides an infrastructure built on Web Services in which modular
components are combined to create a seemingly simple, yet powerful system. The
community-oriented nature generates an economic environment which results in
fair transactions between consumers and providers of computing cycles while
simultaneously encouraging improvements in the infrastructure of the
computational grid itself.
63.
A Survey of Distributed Intrusion Detection Approaches - Treaster, Michael
Distributed intrustion detection systems detect attacks on computer systems
by analyzing data aggregated from distributed sources. The distributed nature
of the data sources allows patterns in the data to be seen that might not be
detectable if each of the sources were examined individually. This paper
describes the various approaches that have been developed to share and analyze
data in such systems, and discusses some issues that must be addressed before
fully decentralized distributed intrusion detection systems can be made viable.
64.
Portfolio selection using neural networks - Fernandez, Alberto; Gomez, Sergio
In this paper we apply a heuristic method based on artificial neural networks
in order to trace out the efficient frontier associated to the portfolio
selection problem. We consider a generalization of the standard Markowitz
mean-variance model which includes cardinality and bounding constraints. These
constraints ensure the investment in a given number of different assets and
limit the amount of capital to be invested in each asset. We present some
experimental results obtained with the neural network heuristic and we compare
them to those obtained with three previous heuristic methods.
65.
A Time-Optimal Delaunay Refinement Algorithm in Two Dimensions - Har-Peled, Sariel; Ungor, Alper
We propose a new refinement algorithm to generate size-optimal
quality-guaranteed Delaunay triangulations in the plane. The algorithm takes
$O(n \log n + m)$ time, where $n$ is the input size and $m$ is the output size.
This is the first time-optimal Delaunay refinement algorithm.
66.
On The Liniar Time Complexity of Finite Languages - Moscu, Mircea Alexandru Popescu
The present paper presents and proves a proposition concerning the time
complexity of finite languages. It is shown herein, that for any finite
language (a language for which the set of words composing it is finite) there
is a Turing machine that computes the language in such a way that for any input
of length k the machine stops in, at most, k + 1 steps.
67.
Public Key Cryptography based on Semigroup Actions - Maze, G.; Monico, C.; Rosenthal, J.
A generalization of the original Diffie-Hellman key exchange in (Z/pZ)* found
a new depth when Miller [21] and Koblitz [9] suggested that such a protocol
could be used with the group over an elliptic curve. In this paper, we extend
such a generalization to the setting of a semigroup action (G-action) on a
finite set. We define these extended protocols, show how it is related to the
general Diffie-Hellman key exchange and give some examples.
68.
Clustering SPIRES with EqRank - Pivovarov, G. B.; Trunov, S. E.
SPIRES is the largest database of scientific papers in the subject field of
high energy and nuclear physics. It contains information on the citation graph
of more than half a million of papers (vertexes of the citation graph). We
outline the EqRank algorithm designed to cluster vertexes of directed graphs,
and present the results of EqRank application to the SPIRES citation graph. The
hierarchical clustering of SPIRES yielded by EqRank is used to set up a web
service, which is also outlined.
69.
A Logic for Non-Monotone Inductive Definitions - Denecker, Marc; Ternovska, Eugenia
Well-known principles of induction include monotone induction and different
sorts of non-monotone induction such as inflationary induction, induction over
well-founded sets and iterated induction. In this work, we define a logic
formalizing induction over well-founded sets and monotone and iterated
induction. Just as the principle of positive induction has been formalized in
FO(LFP), and the principle of inflationary induction has been formalized in
FO(IFP), this paper formalizes the principle of iterated induction in a new
logic for Non-Monotone Inductive Definitions (ID-logic). The semantics of the
logic is strongly influenced by the well-founded semantics of logic
programming. Our main result concerns the modularity properties of inductive
definitions in ID-logic. Specifically, we...
70.
On the Sensitivity of Cyclically-Invariant Boolean Functions - Chakraborty, Sourav
In this paper we construct a cyclically invariant Boolean function whose
sensitivity is $\Theta(n^{1/3})$. This result answers two previously published
questions. Tur\'an (1984) asked if any Boolean function, invariant under some
transitive group of permutations, has sensitivity $\Omega(\sqrt{n})$. Kenyon
and Kutin (2004) asked whether for a ``nice'' function the product of
0-sensitivity and 1-sensitivity is $\Omega(n)$. Our function answers both
questions in the negative.
We also prove that for minterm-transitive functions (a natural class of
Boolean functions including our example) the sensitivity is $\Omega(n^{1/3})$.
Hence for this class of functions sensitivity and block sensitivity are
polynomially related.
71.
From truth to computability II - Japaridze, Giorgi
Computability logic is a formal theory of computational tasks and resources.
Formulas in it represent interactive computational problems, and "truth" is
understood as algorithmic solvability. Interactive computational problems, in
turn, are defined as a certain sort games between a machine and its
environment, with logical operators standing for operations on such games.
Within the ambitious program of finding axiomatizations for incrementally rich
fragments of this semantically introduced logic, the earlier article "From
truth to computability I" proved soundness and completeness for system CL3,
whose language has the so called parallel connectives (including negation),
choice connectives, choice quantifiers, and blind quantifiers. The present
paper extends that result to the significantly more...
72.
Playful, streamlike computation - Curien, Pierre-Louis
We offer a short tour into the interactive interpretation of sequential
programs. We emphasize streamlike computation -- that is, computation of
successive bits of information upon request. The core of the approach surveyed
here dates back to the work of Berry and the author on sequential algorithms on
concrete data structures in the late seventies, culminating in the design of
the programming language CDS, in which the semantics of programs of any type
can be explored interactively. Around one decade later, two major insights of
Cartwright and Felleisen on one hand, and of Lamarche on the other hand gave
new, decisive impulses to the study of sequentiality. Cartwright...
73.
Symmetry and interactivity in Programming - Curien, Pierre-Louis
We recall some of the early occurrences of the notions of interactivity and
symmetry in the operational and denotational semantics of programming
languages. We suggest some connections with ludics.
74.
Introduction to linear logic and ludics, part I - Curien, Pierre-Louis
This two-parts paper offers a survey of linear logic and ludics, which were
introduced by Girard in 1986 and 2001, respectively. Both theories revisit
mathematical logic from first principles, with inspiration from and
applications to computer science. The present part I covers an introduction to
the connectives and proof rules of linear logic, to its decidability
properties, and to its models. Part II will deal with proof nets, a graph-like
representation of proofs which is one of the major innovations of linear logic,
and will present an introduction to ludics.
76.
Introduction to linear logic and ludics, part II - Curien, Pierre-Louis
This paper is the second part of an introduction to linear logic and ludics,
both due to Girard. It is devoted to proof nets, in the limited, yet central,
framework of multiplicative linear logic and to ludics, which has been recently
developped in an aim of further unveiling the fundamental interactive nature of
computation and logic. We hope to offer a few computer science insights into
this new theory.
77.
Maintaining Consistency of Data on the Web - Bernauer, Martin
Increasingly more data is becoming available on the Web, estimates speaking
of 1 billion documents in 2002. Most of the documents are Web pages whose data
is considered to be in XML format, expecting it to eventually replace HTML.
A common problem in designing and maintaining a Web site is that data on a
Web page often replicates or derives from other data, the so-called base data,
that is usually not contained in the deriving or replicating page.
Consequently, replicas and derivations become inconsistent upon modifying base
data in a Web page or a relational database. For example, after assigning a
thesis to a student and modifying...
78.
Augmented Segmentation and Visualization for Presentation Videos - Haubold, Alexander; Kender, John R.
We investigate methods of segmenting, visualizing, and indexing presentation
videos by separately considering audio and visual data. The audio track is
segmented by speaker, and augmented with key phrases which are extracted using
an Automatic Speech Recognizer (ASR). The video track is segmented by visual
dissimilarities and augmented by representative key frames. An interactive user
interface combines a visual representation of audio, video, text, and key
frames, and allows the user to navigate a presentation video. We also explore
clustering and labeling of speaker data and present preliminary results.
79.
Improved Approximation Algorithms for Geometric Set Cover - Clarkson, Kenneth L.; Varadarajan, Kasturi
Given a collection S of subsets of some set U, and M a subset of U, the set
cover problem is to find the smallest subcollection C of S such that M is a
subset of the union of the sets in C. While the general problem is NP-hard to
solve, even approximately, here we consider some geometric special cases, where
usually U = R^d. Extending prior results, we show that approximation algorithms
with provable performance exist, under a certain general condition: that for a
random subset R of S and function f(), there is a decomposition of the portion
of U not covered by R into...
80.
Stochastic Differential Games in a Non-Markovian Setting - Bayraktar, Erhan; Poor, H. Vincent
Stochastic differential games are considered in a non-Markovian setting.
Typically, in stochastic differential games the modulating process of the
diffusion equation describing the state flow is taken to be Markovian. Then
Nash equilibria or other types of solution such as Pareto equilibria are
constructed using Hamilton-Jacobi-Bellman (HJB) equations. But in a
non-Markovian setting the HJB method is not applicable. To examine the
non-Markovian case, this paper considers the situation in which the modulating
process is a fractional Brownian motion. Fractional noise calculus is used for
such models to find the Nash equilibria explicitly. Although fractional
Brownian motion is taken as the modulating process because of its versatility
in modeling in...
61.
