1. Dissimilarity-driven behavior and cooperation in the spatial public goods gameYinhai Fang, Tina Perc Benko, Matjaž Perc, Haiyan Xu, 2019, original scientific article Abstract: In this paper, we explore the impact of four different types of dissimilarity-driven behavior on the evolution of cooperation in the spatial public goods game. While it is commonly assumed that individuals adapt their strategy by imitating one of their more successful neighbors, in reality only very few will be awarded the highest payoffs. Many have equity or equality preferences, and they have to make do with an average or even with a low payoff. To account for this, we divide the population into two categories. One consists of payoff-driven players, while the other consists of dissimilarity-driven players. The later imitate the minority strategy in their group based on four different dissimilaritydriven behaviors. The rule that most effectively promotes cooperation, and this regardless of the multiplication factor of the public goods game, is when individuals adopt the minority strategy only when their payoff is better than that of their neighbors. If the dissimilarity-driven players adopt the minority strategy regardless of the payoffs of others, or if their payoff is the same, the population typically evolves towards a neutral state where cooperators and defectors are equally common. This may be beneficial when the multiplication factor is low, when defectors would otherwise dominate. However, if the dissimilarity-driven players adopt the minority strategy only when their payoff is worse than that of their neighbors, then cooperation is not promoted at all in comparison to the baseline case in the absence of dissimilarity-driven behavior. We explore the pattern formation behind these results, and we discuss their wider implications for the better understanding of cooperative behavior in social groups. Keywords: theoretical biology, evolution, agent-based modeling, complex system, network science, evolutionary game theory Published in DKUM: 26.02.2025; Views: 0; Downloads: 3
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2. Identification of influential invaders in evolutionary populationsGuoli Yang, Tina Perc Benko, Matteo Cavaliere, Jincai Huang, Matjaž Perc, 2019, original scientific article Abstract: The identification of the most influential nodes has been a vibrant subject of research across the whole of network science. Here we map this problem to structured evolutionary populations, where strategies and the interaction network are both subject to change over time based on social inheritance. We study cooperative communities, which cheaters can invade because they avoid the cost of contributions that are associated with cooperation. The question that we seek to answer is at which nodes cheaters invade most successfully. We propose the weighted degree decomposition to identify and rank the most influential invaders. More specifically, we distinguish two kinds of ranking based on the weighted degree decomposition. We show that a ranking strategy based on negative-weighted degree allows to successfully identify the most influential invaders in the case of weak selection, while a ranking strategy based on positive-weighted degree performs better when the selection is strong. Our research thus reveals how to identify the most influential invaders based on statistical measures in dynamically evolving cooperative communities. Keywords: theoretical biology, evolution, agent-based modeling, complex system, network science, evolutionary game theory Published in DKUM: 26.02.2025; Views: 0; Downloads: 4
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3. Cross-sectional personal network analysis of adult smoking in rural areasBianca-Elena Mihǎilǎ, Marian-Gabriel Hâncean, Matjaž Perc, Jürgen Lerner, Iulian Oană, Marius Geanta, José Luis Molina González, Cosmina Cioroboiu, 2024, original scientific article Abstract: Research on smoking behaviour has primarily focused on adolescents, with less attention given to middle-aged and older adults in rural settings. This study examines the influence of personal networks and sociodemographic factors on smoking behaviour in a rural Romanian community. We analysed data from 76 participants, collected through face-to-face interviews, including smoking status (non-smokers, current and former smokers), social ties and demographic details. Multilevel regression models were used to predict smoking status. The results indicate that social networks are essential in shaping smoking habits. Current smokers were more likely to have smoking family members, reinforcing smoking within familial networks, while non-smokers were typically embedded in non-smoking environments. Gender and age patterns show that women were less likely to smoke, and older adults were more likely to have quit smoking. These findings suggest that targeted interventions should focus not only on individuals but also on their social networks. In rural areas, family-based approaches may be particularly effective due to the strong influence of familial ties. Additionally, encouraging connections with non-smokers and former smokers could help disrupt smoking clusters, supporting smoking cessation efforts. Keywords: network science, human behaviour, data science, smoking, social physics Published in DKUM: 03.12.2024; Views: 0; Downloads: 2
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4. Beauty in artistic expressions through the eyes of networks and physicsMatjaž Perc, 2020, review article Abstract: Beauty is subjective, and as such it, of course, cannot be defined in absoluteterms. But we all know or feel when something is beautiful to us personally.And in such instances, methods of statistical physics and network sciencecan be used to quantify and to better understand what it is that evokesthat pleasant feeling, be it when reading a book or looking at a painting.Indeed, recent large-scale explorations of digital data have lifted the veilon many aspects of our artistic expressions that would remain foreverhidden in smaller samples. From the determination of complexity andentropy of art paintings to the creation of the flavour network and the prin-ciples of food pairing, fascinating research at the interface of art, physics andnetwork science abounds. We here review the existing literature, focusing inparticular on culinary, visual, musical and literary arts. We also touch uponcultural history and culturomics, as well as on the connections betweenphysics and the social sciences in general. The review shows that the syner-gies between these fields yield highly entertaining results that can oftenbe enjoyed by layman and experts alike. In addition to its wider appeal,the reviewed research also has many applications, ranging from improvedrecommendation to the detection of plagiarism. Keywords: complexity, entropy, network science, data science, self-organization Published in DKUM: 17.09.2024; Views: 0; Downloads: 413
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5. Inheritance patterns in citation networks reveal scientific memesTobias Kuhn, Matjaž Perc, Dirk Helbing, 2014, original scientific article Abstract: Memes are the cultural equivalent of genes that spread across human culture by means of imitation. What makes a meme and what distinguishes it from other forms of information, however, is still poorly understood. Our analysis of memes in the scientific literature reveals that they are governed by a surprisingly simple relationship between frequency of occurrence and the degree to which they propagate along the citation graph. We propose a simple formalization of this pattern and validate it with data from close to 50 million publication records from the Web of Science, PubMed Central, and the American Physical Society. Evaluations relying on human annotators, citation network randomizations, and comparisons with several alternative approaches confirm that our formula is accurate and effective, without a dependence on linguistic or ontological knowledge and without the application of arbitrary thresholds or filters. Keywords: memes, inheritance, genes, network science, complex systems Published in DKUM: 03.08.2017; Views: 1545; Downloads: 443
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6. Toward the discovery of citation cartels in citation networksIztok Fister, Iztok Fister, Matjaž Perc, 2016, original scientific article Abstract: In this perspective, our goal is to present and elucidate a thus far largely overlooked problem that is arising in scientific publishing, namely the identification and discovery of citation cartels in citation networks. Taking from the well-known definition of a community in the realm of network science, namely that people within a community share significantly more links with each other as they do outside of this community, we propose that citation cartels are defined as groups of authors that cite each other disproportionately more than they do other groups of authors that work on the same subject. Evidently, the identification of citation cartels is somewhat different, although similar to the identification of communities in networks. We systematically expose the problem, provide theoretical examples, and outline an algorithmic guide on how to approach the subject. Keywords: citation network, citation cartel, network science, community detection, cooperation Published in DKUM: 10.07.2017; Views: 1845; Downloads: 430
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7. Fragmented Romanian sociology: growth and structure of the collaboration networkMarian-Gabriel Hâncean, Matjaž Perc, Lazǎr Vlǎsceanu, 2014, original scientific article Abstract: Structural patterns in collaboration networks are essential for understanding how new ideas, research practices, innovation or cooperation circulate and develop within academic communities and between and within university departments. In our research, we explore and investigate the structure of the collaboration network formed by the academics working full-time within all the 17 sociology departments across Romania. We show that the collaboration network is sparse and fragmented, and that it constitutes an environment that does not promote the circulation of new ideas and innovation within the field. Although recent years have witnessed an increase in the productivity of Romanian sociologists, there is still ample room for improvement in terms of the interaction infrastructure that ought to link individuals together so that they could maximize their potentials. We also fail to discern evidence in favor of the Matthew effect governing the growth of the network, which suggests scientific success and productivity are not rewarded. Instead, the structural properties of the collaboration network are partly those of a core-periphery network, where the spread of innovation and change can be explained by structural equivalence rather than by interpersonal influence models. We also provide support for the idea that, within the observed network, collaboration is the product of homophily rather than prestige effects. Further research on the subject based on data from other countries in the region is needed to place our results in a comparative framework, in particular to discern whether the behavior of the Romanian sociologist community is unique or rather common. Keywords: collaboration network, small-world network, community structure, sociology, network science Published in DKUM: 19.06.2017; Views: 1230; Downloads: 421
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