3,250 research outputs found
Advances in complex systems and their applications to cybersecurity
Cybersecurity is one of the fastest growing and largest technology sectors and is increasingly being recognized as one of the major issues in many industries, so companies are increasing their security budgets in order to guarantee the security of their processes. Successful menaces to the security of information systems could lead to safety, environmental, production, and quality problems.
One of the most harmful issues of attacks and intrusions is the ever-changing nature of attack technologies and strategies, which increases the difficulty of protecting computer systems. As a result, advanced systems are required to deal with the ever-increasing complexity of attacks in order to protect systems and information
Spin-models of granular compaction: From one-dimensional models to random graphs
We discuss two athermal types of dynamics suitable for spin-models designed
to model repeated tapping of a granular assembly. These dynamics are applied to
a range of models characterised by a 3-spin Hamiltonian aiming to capture the
geometric frustration in packings of granular matter.Comment: Contribution to "Challenges in Granular Media", ICTP Trieste; to
appear in 'Advances in Complex Systems
Interactions In Space For Archaeological Models
In this article we examine a variety of quantitative models for describing
archaeological networks, with particular emphasis on the maritime networks of
the Aegean Middle Bronze Age. In particular, we discriminate between those
gravitational networks that are most likely (maximum entropy) and most
efficient (best cost/benefit outcomes).Comment: 21 pages, 6 figures, 2 tables. Contribution to special issue of
Advances in Complex Systems from the conference `Cultural Evolution in
Spatially Structured Populations', UCL, London, September 2010. To appear in
Advances in Complex System
Forecasting price increments using an artificial Neural Network
Financial forecasting is a difficult task due to the intrinsic complexity of
the financial system. In the present paper we relate our experience using
neural nets as financial time series forecast method. In particular we show
that a neural net able to forecast the sign of the price increments with a
success rate slightly above 50 percent can be found.Comment: 12 pages, 5 figures (to be published in Advances in Complex Systems,
as the Proceeding of the WE-Heraeus Workshop on "Economic Dynamics from the
Physics Point of View", Bad Honnef, Germany, March 27-30, 200
Multi-market minority game: breaking the symmetry of choice
Generalization of the minority game to more than one market is considered. At
each time step every agent chooses one of its strategies and acts on the market
related to this strategy. If the payoff function allows for strong fluctuation
of utility then market occupancies become inhomogeneous with preference given
to this market where the fluctuation occured first. There exists a critical
size of agent population above which agents on bigger market behave
collectively. In this regime there always exists a history of decisions for
which all agents on a bigger market react identically.Comment: 15 pages, 12 figures, Accepted to 'Advances in Complex Systems
Modeling two-language competition dynamics
During the last decade, much attention has been paid to language competition
in the complex systems community, that is, how the fractions of speakers of
several competing languages evolve in time. In this paper we review recent
advances in this direction and focus on three aspects. First we consider the
shift from two-state models to three state models that include the possibility
of bilingual individuals. The understanding of the role played by bilingualism
is essential in sociolinguistics. In particular, the question addressed is
whether bilingualism facilitates the coexistence of languages. Second, we will
analyze the effect of social interaction networks and physical barriers.
Finally, we will show how to analyze the issue of bilingualism from a game
theoretical perspective.Comment: 15 pages, 5 figures; published in the Special Issue of Advances in
Complex Systems "Language Dynamics
Evolution of Wikipedia's Category Structure
Wikipedia, as a social phenomenon of collaborative knowledge creating, has
been studied extensively from various points of views. The category system of
Wikipedia, introduced in 2004, has attracted relatively little attention. In
this study, we focus on the documentation of knowledge, and the transformation
of this documentation with time. We take Wikipedia as a proxy for knowledge in
general and its category system as an aspect of the structure of this
knowledge. We investigate the evolution of the category structure of the
English Wikipedia from its birth in 2004 to 2008. We treat the category system
as if it is a hierarchical Knowledge Organization System, capturing the changes
in the distributions of the top categories. We investigate how the clustering
of articles, defined by the category system, matches the direct link network
between the articles and show how it changes over time. We find the Wikipedia
category network mostly stable, but with occasional reorganization. We show
that the clustering matches the link structure quite well, except short periods
preceding the reorganizations.Comment: Preprint of an article submitted for consideration in Advances in
Complex Systems (2012) http://www.worldscinet.com/acs/, 19 pages, 7 figure
Adaptive Investment Strategies For Periodic Environments
In this paper, we present an adaptive investment strategy for environments
with periodic returns on investment. In our approach, we consider an investment
model where the agent decides at every time step the proportion of wealth to
invest in a risky asset, keeping the rest of the budget in a risk-free asset.
Every investment is evaluated in the market via a stylized return on investment
function (RoI), which is modeled by a stochastic process with unknown
periodicities and levels of noise. For comparison reasons, we present two
reference strategies which represent the case of agents with zero-knowledge and
complete-knowledge of the dynamics of the returns. We consider also an
investment strategy based on technical analysis to forecast the next return by
fitting a trend line to previous received returns. To account for the
performance of the different strategies, we perform some computer experiments
to calculate the average budget that can be obtained with them over a certain
number of time steps. To assure for fair comparisons, we first tune the
parameters of each strategy. Afterwards, we compare the performance of these
strategies for RoIs with different periodicities and levels of noise.Comment: Paper submitted to Advances in Complex Systems (November, 2007) 22
pages, 9 figure
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