1. Two-by-two ordinal patterns in art paintingsMateus M. Tarozo, Arthur A. B. Pessa, Luciano Zunino, Osvaldo A. Rosso, Matjaž Perc, Haroldo V. Ribeiro, 2025, izvirni znanstveni članek Opis: Quantitative analysis of visual arts has recently expanded to encompass a more extensive array of artworks due to the availability of large-scale digitized art collections. Consistent with formal analyses by art historians, many of these studies highlight the significance of encoding spatial structures within artworks to enhance our understanding of visual arts. However, defining universally applicable, interpretable, and sufficiently simple units that capture the essence of paintings and their artistic styles remains challenging. Here, we examine ordering patterns in pixel intensities within two-by-two partitions of images from nearly 140,000 paintings created over the past 1,000 years. These patterns, categorized into 11 types based on arguments of continuity and symmetry, are both universally applicable and detailed enough to correlate with low-level visual features of paintings. We uncover a universal distribution of these patterns, with consistent prevalence within groups, yet modulated across groups by a nontrivial interplay between pattern smoothness and the likelihood of identical pixel intensities. This finding provides a standardized metric for comparing paintings and styles, further establishing a scale to measure deviations from the average prevalence. Our research also shows that these simple patterns carry valuable information for identifying painting styles, though styles generally exhibit considerable variability in the prevalence of ordinal patterns. Moreover, shifts in the prevalence of these patterns reveal a trend in which artworks increasingly diverge from the average incidence over time; however, this evolution is neither smooth nor uniform, with substantial variability in pattern prevalence, particularly after the 1930s. Ključne besede: spatial patterns, complexity, esthetic measure, art history, social physics Objavljeno v DKUM: 01.04.2025; Ogledov: 0; Prenosov: 3
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2. Strong geodetic problem in networksPaul Manuel, Sandi Klavžar, Antony Xavier, Andrew Arokiaraj, Elizabeth Thomas, 2020, izvirni znanstveni članek Opis: In order to model certain social network problems, the strong geodetic problem and its related invariant, the strong geodetic number, are introduced. The problem is conceptually similar to the classical geodetic problem but seems intrinsically more difficult. The strong geodetic number is compared with the geodetic number and with the isometric path number. It is determined for several families of graphs including Apollonian networks. Applying Sierpiński graphs, an algorithm is developed that returns a minimum path cover of Apollonian networks corresponding to the strong geodetic number. It is also proved that the strong geodetic problem is NP-complete. Ključne besede: geodetic problem, strong geodetic problem, Apollonian networks, Sierpiński graphs, computational complexity Objavljeno v DKUM: 11.03.2025; Ogledov: 0; Prenosov: 4
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3. A survey on packing coloringsBoštjan Brešar, Jasmina Ferme, Sandi Klavžar, Douglas F. Rall, 2020, pregledni znanstveni članek Opis: If S=(a1,a2,...) is a non-decreasing sequence of positive integers, then an S-packing coloring of a graph G is a partition of V (G) into sets X1,X2,... such that for each pair of distinct vertices in the set Xi, the distance between them is larger than ai. If there exists an integer k such that V(G)=X1 U ... U Xk, then the partition is called an S-packing k-coloring. The S-packing chromatic number of G is the smallest k such that G admits an S-packing k-coloring. If ai=i for every i, then the terminology reduces to packing colorings and packing chromatic number. Since the introduction of these generalizations of the chromatic number in 2008 more than fifty papers followed. Here we survey the state of the art on the packing coloring, and ts generalization, the S-packing coloring. We also list several conjecres and open problems. Ključne besede: packing coloring, packing chromatic number, subcubic graph, S-packing chromatic number, computational complexity Objavljeno v DKUM: 11.03.2025; Ogledov: 0; Prenosov: 5
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4. Lowland forest fragment characteristics and anthropogenic disturbances determine alien plant species richness and compositionMirjana Šipek, Nina Šajna, 2024, izvirni znanstveni članek Opis: Loss of habitat and biological invasion are the main threats to biodiversity. In intensive agricultural or urban landscapes, forest fragments, even if they are small and isolated represent biodiversity refugia. Environmental variables such as landscape structure, abiotic conditions and anthropogenic disturbance affect the biodiversity of the fragments. In this study, we explored plant species richness in 48 forest fragments embedded in predominantly agricultural landscapes on the alluvial plains of the Mura and Drava rivers in NE Slovenia. We determined several forest fragment characteristics such as perimeter, area, shape complexity, length and proportion of edge shared with adjacent land-cover types and anthropogenic disturbance indicated by the presence of footpaths and waste disposed in fragments. The abiotic condition of these fragments was assessed by Ellenberg indicator values. We built generalized linear models and ordination analyses to assess the importance of environmental variables for the richness and composition of alien plant species and other ecologically meaningful plant groups. Shape complexity had a consistent positive effect on the richness of native and alien plants species. Major drivers of alien plant composition in forest fragments included adjacent land-cover and urbanization level. An increasing proportion of arable land along the forest fragment perimeter negatively affected the richness of alien plants, while the effect of urban areas was positive. Our results confirmed that forest fragments in the rural-urban matrix represent biodiversity refugia and support native plant species; however, they are not resistant to invasions; instead invasion depends on the land-cover type in the surroundings of a given forest fragment. Ključne besede: agricultural land, urban area, settlements, fragment size, fragment shape complexity, ornamental plants Objavljeno v DKUM: 29.11.2024; Ogledov: 0; Prenosov: 11
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5. Beauty in artistic expressions through the eyes of networks and physicsMatjaž Perc, 2020, pregledni znanstveni članek Opis: 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. Ključne besede: complexity, entropy, network science, data science, self-organization Objavljeno v DKUM: 17.09.2024; Ogledov: 0; Prenosov: 414
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6. Kolmogorov compression complexity may differentiate different schools of Orthodox iconographyDaniel Peptenatu, Ion Andronache, Helmut Ahammer, Richard Taylor, Ioannis Liritzis, Marko Radulovic, Bogdan Ciobanu, Marin Burcea, Matjaž Perc, Tuan D. Pham, 2022, izvirni znanstveni članek Opis: The complexity in the styles of 1200 Byzantine icons painted between 13th and 16th from Greece, Russia and Romania was investigated through the Kolmogorov algorithmic information theory. The aim was to identify specific quantitative patterns which define the key characteristics of the three different painting schools. Our novel approach using the artificial surface images generated with Inverse FFT and the Midpoint Displacement (MD) algorithms, was validated by comparison of results with eight fractal and non-fractal indices. From the analyzes performed, normalized Kolmogorov compression complexity (KC) proved to be the best solution because it had the best complexity pattern differentiations, is not sensitive to the image size and the least affected by noise. We conclude that normalized KC methodology does offer capability to differentiate the icons within a School and amongst the three Schools. Ključne besede: iconography, complexity, Kolmogorov compression, art, physics Objavljeno v DKUM: 15.07.2024; Ogledov: 117; Prenosov: 16
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7. Deep learning criminal networksHaroldo V. Ribeiro, Diego D. Lopes, Arthur A. B. Pessa, Alvaro F. Martins, Bruno R. da Cunha, Sebastián Gonçalves, Ervin K. Lenzi, Quentin S. Hanley, Matjaž Perc, 2023, izvirni znanstveni članek Opis: Recent advances in deep learning methods have enabled researchers to develop and apply algorithms for the analysis and modeling of complex networks. These advances have sparked a surge of interest at the interface between network science and machine learning. Despite this, the use of machine learning methods to investigate criminal networks remains surprisingly scarce. Here, we explore the potential of graph convolutional networks to learn patterns among networked criminals and to predict various properties of criminal networks. Using empirical data from political corruption, criminal police intelligence, and criminal financial networks, we develop a series of deep learning models based on the GraphSAGE framework that are able to recover missing criminal partnerships, distinguish among types of associations, predict the amount of money exchanged among criminal agents, and even anticipate partnerships and recidivism of criminals during the growth dynamics of corruption networks, all with impressive accuracy. Our deep learning models significantly outperform previous shallow learning approaches and produce high-quality embeddings for node and edge properties. Moreover, these models inherit all the advantages of the GraphSAGE framework, including the generalization to unseen nodes and scaling up to large graph structures. Ključne besede: organized crime, complexity, crime prediction, GraphSAGE Objavljeno v DKUM: 20.06.2024; Ogledov: 236; Prenosov: 13
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9. Systems approach to tourism : a methodology for defining complex tourism systemTadeja Jere Lazanski, 2017, izvirni znanstveni članek Opis: Background and Purpose: The complexity of the tourism system, as well as modelling in a frame of system dynamics, will be discussed in this paper. The phaenomenon of tourism, which possesses the typical properties of global and local organisations, will be presented as an open complex system with all its elements, and an optimal methodology to explain the relations among them. The approach we want to present is due to its transparency an excellent tool for searching systems solutions and serves also as a strategic decision-making assessment. We will present systems complexity and develop three models of a complex tourism system: the first one will present tourism as an open complex system with its elements, which operate inside of a tourism market area. The elements of this system present subsystems, which relations and interdependencies will be explained with two models: causal-loop diagram and a simulation model in frame of systems dynamics.
Design/methodology/approach: Systems methodology will be shown as the appropriate one, when we discuss complex systems challenges. For illustration, systems approach and systems methodology will be applied to tourism models. With building a qualitative causal-loop diagram we will describe the tourism system complexity in forms of system%s elements relations. Mutual influences among the elements will be presented with positive and negative loops, which forms circles of reinforcement and balance. This will help us to discuss the problem categorically. The final model will follow the causal-loop diagram. This will be a simulation model in a frame of system dynamics as an illustration of the discussed methodology.
Results: The methodology offers the solution of effective and holistic promotion of complex tourism system transformation, which has the potential to go beyond the myth of sustainable tourism and create significant shifts in the approach and acting of the participants (elements of the system) involved. Systems approach brings to tourism and the society, in general, broader dimensions of thinking, the awareness interdependency, interconnectivity, and responsibility for the behaviour of a system, which can be observed by feedback loops.
Conclusions: Findings about meaningfulness of systems thinking presented in the paper, are rarely presented to tourism society systemically and with the aim of designing sustainable complex tourism system. They show new approach, systems awareness and teaches thinking %out of the box%. Consequently, the sustainable behaviour is achieved: tourism supply and demand meet on responsible base and they connect to responsible stakeholders. Ključne besede: systems approach, complexity, tourism system, modelling, system dynamics Objavljeno v DKUM: 22.01.2018; Ogledov: 1144; Prenosov: 213
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10. Organisational effectiveness and customer satisfactionMilan Ambrož, Martina Praprotnik, 2008, izvirni znanstveni članek Opis: This paper presents a test of the relationship between organizational culture as a crucial indicator of organizational effectiveness and customer satisfaction using service-unit data from two health resorts. Ensuring survival of the service organisation in the long run requires adaptations which are oriented towards achieving maximum customer satisfaction. This study intended to unveil the effect organisational factors have on customer service orientation from the customer and employee point of view within a two health resort service setting. The finding suggests that when trying to predict the comparative degree which organisational effectiveness factors have in satisfying customers' needs, performance, adaptability and mission can be of the highest importance. Some effects like performance were uniform for employees and customers, while others varied depending on the organisation and the customer or employee group. Furthermore, findings suggest that service performance and organisation mission of the service organisation predict customer satisfaction based on established and proven health services. In this context there is no room for innovation, despite the fact that employees and customers do not share similar views about the impact of organisational effectiveness. Developing an effective service organisation can provide a competitive advantage to the organisation. Critical for the success of the service organisation is that organisational agents have a clear view of the existing organisation effectiveness and a clear view of the customer expectations in this area. Ključne besede: organisational effectiveness, customer satisfaction, customer complexity, service orientation, survival, adaptability Objavljeno v DKUM: 04.12.2017; Ogledov: 1638; Prenosov: 455
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