14,156 research outputs found
Assessing Simulations of Imperial Dynamics and Conflict in the Ancient World
The development of models to capture large-scale dynamics in human history is
one of the core contributions of cliodynamics. Most often, these models are
assessed by their predictive capability on some macro-scale and aggregated
measure and compared to manually curated historical data. In this report, we
consider the model from Turchin et al. (2013), where the evaluation is done on
the prediction of "imperial density": the relative frequency with which a
geographical area belonged to large-scale polities over a certain time window.
We implement the model and release both code and data for reproducibility. We
then assess its behaviour against three historical data sets: the relative size
of simulated polities vs historical ones; the spatial correlation of simulated
imperial density with historical population density; the spatial correlation of
simulated conflict vs historical conflict. At the global level, we show good
agreement with population density (), and some agreement with
historical conflict in Europe (). The model instead fails to
reproduce the historical shape of individual polities. Finally, we tweak the
model to behave greedily by having polities preferentially attacking weaker
neighbours. Results significantly degrade, suggesting that random attacks are a
key trait of the original model. We conclude by proposing a way forward by
matching the probabilistic imperial strength from simulations to inferred
networked communities from real settlement data
Individual Security and Network Design with Malicious Nodes
Networks are beneficial to those being connected but can also be used as
carriers of contagious hostile attacks. These attacks are often facilitated by
exploiting corrupt network users. To protect against the attacks, users can
resort to costly defense. The decentralized nature of such protection is known
to be inefficient but the inefficiencies can be mitigated by a careful network
design. Is network design still effective when not all users can be trusted? We
propose a model of network design and defense with byzantine nodes to address
this question. We study the optimal defended networks in the case of
centralized defense and, for the case of decentralized defense, we show that
the inefficiencies due to decentralization can be fully mitigated, despite the
presence of the byzantine nodes.Comment: 19 pages, 3 figure
Application of Steganography for Anonymity through the Internet
In this paper, a novel steganographic scheme based on chaotic iterations is
proposed. This research work takes place into the information hiding security
framework. The applications for anonymity and privacy through the Internet are
regarded too. To guarantee such an anonymity, it should be possible to set up a
secret communication channel into a web page, being both secure and robust. To
achieve this goal, we propose an information hiding scheme being stego-secure,
which is the highest level of security in a well defined and studied category
of attacks called "watermark-only attack". This category of attacks is the best
context to study steganography-based anonymity through the Internet. The
steganalysis of our steganographic process is also studied in order to show it
security in a real test framework.Comment: 14 page
Organic Design of Massively Distributed Systems: A Complex Networks Perspective
The vision of Organic Computing addresses challenges that arise in the design
of future information systems that are comprised of numerous, heterogeneous,
resource-constrained and error-prone components or devices. Here, the notion
organic particularly highlights the idea that, in order to be manageable, such
systems should exhibit self-organization, self-adaptation and self-healing
characteristics similar to those of biological systems. In recent years, the
principles underlying many of the interesting characteristics of natural
systems have been investigated from the perspective of complex systems science,
particularly using the conceptual framework of statistical physics and
statistical mechanics. In this article, we review some of the interesting
relations between statistical physics and networked systems and discuss
applications in the engineering of organic networked computing systems with
predictable, quantifiable and controllable self-* properties.Comment: 17 pages, 14 figures, preprint of submission to Informatik-Spektrum
published by Springe
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