Jonah E. Friederich, Everton S. Medeiros, Sabine H. L. Klapp, Anna Zakharova

In networked systems, stochastic resonance occurs as a collective phenomenon where the entire stochastic network resonates with a weak applied periodic signal. Beyond the interplay among the network coupling, the amplitude of the external periodic signal, and the intensity of stochastic fluctuations, the maintenance of stochastic resonance also crucially depends on the resonance capacity of each oscillator composing the network. This scenario raises the question: Can local defects in the ability of oscillators to resonate break down the stochastic resonance phenomenon in the entire network? Here, we investigate this possibility in complex networks of prototypical bistable oscillators in a double-well potential. We test the sustainability of stochastic resonance by considering a fraction of network oscillators with nonresonant potential landscapes. We find that the number of nonresonant oscillators depends nonlinearly on their dissimilarity from the rest of the network oscillators. In addition, we unravel the role of the network topology and coupling strength in maintaining, or suppressing, the stochastic resonance for different noise levels and number of nonresonant oscillators. Finally, we obtain a low-dimensional deterministic model confirming the results observed for the networks.

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Paolo Cornale, Michele Tizzani, Fabio Ciulla, Kyriaki Kalimeri, Elisa Omodei, Daniela Paolotti, Yelena Mejova
Collective and individual action necessary to address climate change hinges on the public’s understanding of the relevant scientific findings. In this study, we examine the use of scientific sources in the course of 14 years of public deliberation around climate change on one of the largest social media platforms, Reddit. We find that only 4.0% of the links in the Reddit posts, and 6.5% in the comments, point to domains of scientific sources, although these rates have been increasing in the past decades. These links are dwarfed, however, by the citations of mass media, newspapers, and social media, the latter of which peaked especially during 2019-2020. Further, scientific sources are more likely to be posted by users who also post links to sources having central-left political leaning, and less so by those posting more polarized sources. Unfortunately, scientific sources are not often used in response to links to unreliable sources.

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Mario Franco, Gerardo Febres, Nelson Fernández, Carlos Gershenson

Classification is a ubiquitous and fundamental problem in artificial intelligence and machine learning, with extensive efforts dedicated to developing more powerful classifiers and larger datasets. However, the classification task is ultimately constrained by the intrinsic properties of datasets, independently of computational power or model complexity. In this work, we introduce a formal entropy-based measure of classificability, which quantifies the inherent difficulty of a classification problem by assessing the uncertainty in class assignments given feature representations. This measure captures the degree of class overlap and aligns with human intuition, serving as an upper bound on classification performance for classification problems. Our results establish a theoretical limit beyond which no classifier can improve the classification accuracy, regardless of the architecture or amount of data, in a given problem. Our approach provides a principled framework for understanding when classification is inherently fallible and fundamentally ambiguous.

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Matthew Russell Barnes, Vincenzo Nicosia, Richard G. Clegg
In complex networks, the rich-get-richer effect (nodes with high degree at one point in time gain more degree in their future) is commonly observed. In practice this is often studied on a static network snapshot, for example, a preferential attachment model assumed to explain the more highly connected nodes or a rich-club}effect that analyses the most highly connected nodes. In this paper, we consider temporal measures of how success (measured here as node degree) propagates across time. By analogy with social mobility (a measure people moving within a social hierarchy through their life) we define hierarchical mobility to measure how a node’s propensity to gain degree changes over time. We introduce an associated taxonomy of temporal correlation statistics including mobility, philanthropy and community. Mobility measures the extent to which a node’s degree gain in one time period predicts its degree gain in the next. Philanthropy and community measure similar properties related to node neighbourhood.
We apply these statistics both to artificial models and to 26 real temporal networks. We find that most of our networks show a tendency for individual nodes and their neighbourhoods to remain in similar hierarchical positions over time, while most networks show low correlative effects between individuals and their neighbourhoods. Moreover, we show that the mobility taxonomy can discriminate between networks from different fields. We also generate artificial network models to gain intuition about the behaviour and expected range of the statistics. The artificial models show that the opposite of the “rich-get-richer” effect requires the existence of inequality of degree in a network. Overall, we show that measuring the hierarchical mobility of a temporal network is an invaluable resource for discovering its underlying structural dynamics.

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Competence Modelling From the Perspective of Complex Systems Theories: A Systematic Literature Review

Pedagogika Vol. 156 No. 4

This article aims to investigate how the notion of competence is conceptualised and modelled from the point of view of complex systems theories. Although the importance of competences and competency-based education is widely acknowledged, the concept of competence keeps evolving and it remains difficult to define it in today’s constantly changing and uncertain VUCA world. Therefore, this study explores how the approach of complex systems, which is increasingly more often applied in educational research, can contribute to the definition of competence. The article presents a systematic review of 21 articles published in various databases in 2000-2023, revealing that from the perspective of complex systems, competence can be conceptualised both at the individual level and at the level of the whole system or organisation; it can follow a functionalist or contextual approach. Based on the research findings, it is assumed that in certain cases competence can be treated as emergence or even as an entire complex system, characterised by such properties as non-linearity, chaos, emergence, feedback loops, etc. Finally, this article reviews the variety of complexity-informed mathematical/computational and theoretical models utilised in the reviewed studies, the application of which opens up new avenues in overall educational research.

Read the full article at: ejournals.vdu.lt