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Contagion processes have been proven to fundamentally depend on the structural properties of the interaction networks conveying them. Many real networked systems are characterized by clustered substructures representing either collections of all-to-all pair-wise interactions (cliques) and/or group interactions, involving many of their members at once. In this work, focusing on interaction structures represented as simplicial complexes, we present a discrete-time microscopic model of complex contagion for a susceptible-infected-susceptible dynamics. Introducing a particular edge clique cover and a heuristic to find it, the model accounts for the higher-order dynamical correlations among the members of the substructures (cliques/simplices). The analytical computation of the critical point reveals that higher-order correlations are responsible for its dependence on the higher-order couplings. While such dependence eludes any mean-field model, the possibility of a bi-stable region is extended to structured populations. Higher-order contagion models capture opinion dynamics and adoption of behavior in social networks. In this paper, the authors propose a mathematical framework able to accurately characterize the phase diagram of these contagion processes in social higher-order networks. [ABSTRACT FROM AUTHOR]

Accessing resources in peer groups is essential for youth's survival and reproduction. To date, little is known about the behavioral strategies used by socially prominent preadolescent and early adolescent resource controllers in peer cliques, groups of individuals who hang out together during free time at school. Theory suggests that clique hierarchical organization should influence forceful resource control behavior of central (prominent) clique members, but evidence is mixed. This study examined the effects of clique hierarchical organization on forceful behavior used by central clique members to obtain a special toy during a 5-minute resource contest with clique-mates. Participants were 696 children (59.91% girls) ranging from 9 to 14 years (Mage = 11.59) in 147 cliques. Resource control, and prosocial, coercive, and bistrategic (hybrid prosocial and coercive) bids were recorded. Neither centrality nor hierarchy predicted resource control bid use, but centrality and bistrategic bids predicted resource control. Clique stratification (status differences among members) but not clique structure (shape of hierarchy) moderated the outcome of central clique members' bistrategic bids. Bistrategic bids advantaged central members of low-stratified but not highly stratified cliques, indicating that greater power is needed for resource control in cliques with numerous central members. However, high clique stratification did not quell the need for forceful behavior by central (or other) clique members. These findings suggest that for prominent preadolescent and early adolescent clique members, material resource control is the product of both mitigated force and acquiescence by clique-mates. [ABSTRACT FROM AUTHOR]

The first output-sensitive algorithm for the Maximal Clique Listing problem was given by Tsukiyama et al. (SIAM J Comput 6(3):505-517, 1977). As any algorithm falling within the Reverse Search paradigm, it performs a DFS visit of a directed tree (the RS-tree) having the objects to be listed (i.e., maximal cliques) as its nodes. In a recursive implementation, the RS-tree corresponds to the recursion tree of the algorithm. The time delay is given by the cost of generating the next child of a node, and Tsukiyama et al. showed it is O(mn). Makino and Uno (in: Hagerup, Katajainen (eds) Algorithm theory: SWAT 2004. Lecture notes in computer science, Springer, Berlin, pp 260-272, 2004) sharpened the time delay to O(nω) by generating all the children of a node in one single shot, which is performed by computing a square fast matrix multiplication. In this paper we further improve the asymptotics for the exploration of the same RS-tree by grouping the offsprings’ computation even further. Our idea is to rely on rectangular fast matrix multiplication in order to compute all children of n2 nodes in one single shot. According to the current upper bounds on square and rectangular fast matrix multiplication, with this the time delay improves from O(n2.3728639) to O(n2.093362), keeping a polynomial work space. [ABSTRACT FROM AUTHOR]

Grounded in the experiences of 30 gang-involved respondents in Calgary, this Canadian study examined criminal gang involvement of youth from immigrant families. Our analysis showed that gang-involved youth had experienced multiple, severe and prolonged personal and interpersonal challenges in all facets of their lives and that gradual disintegration of their relationships with family, school and community had resulted in the unravelling of self-concept, ethnic identity, sense of belonging and sense of citizenship and progressively propelled them towards membership in high-risk social cliques and criminal gangs. Our findings brought attention to the need for coordinated, comprehensive support for youth from immigrant families through family-based, school-based and community-based programs. [ABSTRACT FROM AUTHOR]

In a wide variety of emerging data-intensive applications, such as social network analysis, Web document clustering, entity resolution, and detection of consistently co-expressed genes in systems biology, the detection of dense subgraphs (cliques) is an essential component. Unfortunately, this problem is NP-Complete and thus computationally intensive at scale-hence there is a need for efficient processing, as well as the techniques for distributing the computation across multiple machines such that the computation, which is too time-consuming on a single machine, can be efficiently performed on a machine cluster given that it is large enough. In this paper, we propose a new algorithm (called GP) for maximal clique enumeration. It identifies cliques by the operation of binary graph partitioning, which iteratively divides a graph until each task is sufficiently small to be processed in parallel. Given a connected graph $$G=(V,E)$$ , the GP algorithm has a space complexity of O(| E|) and a time complexity of $$O(|E|\mu (G))$$ , where $$\mu (G)$$ represents the number of different cliques existing in G. We also present a hybrid algorithm, which can effectively leverage the advantages of both the GP algorithm and the classical Bron-and-Kerbosch (BK) algorithm. Then, we develop corresponding parallel solutions based on the GP and hybrid algorithms. Finally, we evaluate the performance of the proposed solutions on real and synthetic graph data. Our extensive experiments show that in both centralized and parallel setting, our proposed GP and hybrid approaches achieve considerably better performance than the state-of-the-art BK approach. Our parallel solutions are implemented and evaluated on MapReduce, a popular shared-nothing parallel framework, but can easily generalize to other shared-nothing or shared-memory parallel frameworks. [ABSTRACT FROM AUTHOR]

The literature increasingly acknowledges that international institutions do not exist in isolation, but regularly interact with each other. This interplay might induce influence, affecting institutions' development and performance. The following research adds to this debate by systematically analyzing the quantitative evidence on how institutional interaction drives institutional design from a network perspective. Using dyadic cross-sectional data on international environmental agreements in 1952-2000, the authors find support for their theoretical argument that regimes' similarity in design as captured by their degree of legalization strongly depends on institutions' interaction. However, while 'soft law' disseminates between regimes that are well connected through direct or indirect links, this does not apply to 'hard law.' The authors explain this divergence with states' concerns about binding-law commitments and sovereignty costs associated with the latter. This research may have important implications for studies of international institutions and of network analysis in general. [ABSTRACT FROM AUTHOR]

Adolescents tend to form friendships with similar peers and, in turn, their friends further influence adolescents' behaviors and attitudes. Emerging work has shown that these selection and influence processes also might extend to bully victimization. However, no prior work has examined selection and influence effects involved in bully victimization within cliques, despite theoretical account emphasizing the importance of cliques in this regard. This study examined selection and influence processes in adolescence regarding bully victimization both at the level of the entire friendship network and the level of cliques. We used a two-wave design (5-month interval). Participants were 543 adolescents (50.1 % male, Mage = 15.8) in secondary education. Stochastic actor-based models indicated that at the level of the larger friendship network, adolescents tended to select friends with similar levels of bully victimization as they themselves. In addition, adolescent friends influenced each other in terms of bully victimization over time. Actor Parter Interdependence models showed that similarities in bully victimization between clique members were not due to selection of clique members. For boys, average clique bully victimization predicted individual bully victimization over time (influence), but not vice versa. No influence was found for girls, indicating that different mechanisms may underlie friend influence on bully victimization for girls and boys. The differences in results at the level of the larger friendship network versus the clique emphasize the importance of taking the type of friendship ties into account in research on selection and influence processes involved in bully victimization. [ABSTRACT FROM AUTHOR]

Peer cliques form an important context for the social development of adolescents. Although clique members are often similar in social status, also within cliques, status differences exist. How differences in social status between clique members are related to behaviors of its individual members is rather unknown. This study examined to what extent the relationship of individual social status (i.e., perceived popularity) with aggression and prosocial behavior depends on the level of internal clique hierarchy. The sample consists of 2674 adolescents (49.8 % boys), with a mean age of 14.02. We focused specifically on physical and relational aggression, and practical and emotional support, because these behaviors have shown to be of great importance for social relationships and social standing among adolescents. The internal status hierarchy of cliques was based on the variation in individual social status between clique members (i.e., clique hierarchization) and the structure of status scores within a clique (pyramid shape, inverted pyramid, or equal distribution of social status scores) (i.e., clique status structure). The results showed that differences in aggressive and prosocial behaviors were particularly moderated by clique status structure: aggression was stronger related to individual social status in (girls') cliques where the clique status structure reflected an inverted pyramid with relatively more high status adolescents within the clique than low status peers, and prosocial behavior showed a significant relationship with individual social status, again predominantly in inverted pyramid structured (boys' and girls') cliques. Furthermore, these effects differed by types of gender cliques: the associations were found in same gender but not mixed-gender cliques. The findings stress the importance of taking into account internal clique characteristics when studying adolescent social status in relationship to aggression and prosociality. [ABSTRACT FROM AUTHOR]

Detecting quasi-cliques in graphs is a useful tool for detecting dense clusters in graph-based data mining. Particularly in large-scale data sets that are error-prone, cliques are overly restrictive and impractical. Quasi-clique detection has been accomplished using heuristic approaches in various applications of graph-based data mining in protein interaction networks, gene co-expression networks, and telecommunication networks. Quasi-cliques are not hereditary, in the sense that every subset of a quasi-clique need not be a quasi-clique. This lack of heredity introduces interesting challenges in the development of exact algorithms to detect maximum cardinality quasi-cliques. The only exact approaches for this problem are limited to two mixed integer programming formulations that were recently proposed in the literature. The main contribution of this article is a new combinatorial branch-and-bound algorithm for the maximum quasi-clique problem. [ABSTRACT FROM AUTHOR]

Hyperlink cinema is an emergent film genre that seeks to push the boundaries of the medium in order to mirror contemporary life in the globalized community. Films in the genre thus create an interacting network across space and time in such a way as to suggest that people's lives can intersect on scales that would not have been possible without modern technologies of travel and communication. This allows us to test the hypothesis that new kinds of media might permit us to break through the natural cognitive constraints that limit the number and quality of social relationships we can manage in the conventional face-to-face world. We used network analysis to test this hypothesis with data from 12 hyperlink films, using 10 motion pictures from a more conventional film genre as a control. We found few differences between hyperlink cinema films and the control genre, and few differences between hyperlink cinema films and either the real world or classical drama (e.g., Shakespeare's plays). Conversation group size seems to be especially resilient to alteration. It seems that, despite many efficiency advantages, modern media are unable to circumvent the constraints imposed by our evolved psychology. [ABSTRACT FROM AUTHOR]

Cyber-bullying, and other issues related to violence being committed online in prosocial environments, are beginning to constitute an emergency worldwide. Institutions are particularly sensitive to the problem especially as far as teenagers are concerned inasmuch as, in cases of inter-teen episodes, the deterrent power of ordinary justice (i.e. threaten to sue) is not as effective as it is between adults. In order to develop the most suitable policies, institution should not be satisfied with statistics and sociological perspectives on the phenomenon, but rather seek a deep ethical understanding—also referring to the biological and evolutionary past of human beings. The aim of this paper is to show a way to fill this theoretical gap, offering some answers (and some questions too) that can illuminate future policy-oriented research and reflection. In order to do so, we will start by connecting our argument to evolutionary studies carried out in the past two decades, focusing on gossip as a tool for social assortment, thus endowed with a dual function: protect the group from free riders, intruders and bullies but also bully the deviant members. In the “Mediating gossip through social networks” section, we will see which aspects of gossip, vital for bullying, are co-opted by social network scenarios. A fundamental trait of human social life, that is the subdivision in smaller coalitions, or sub-groups, will be shown as missing in social networks (SN) dynamics—therefore constituting themselves as structurally violent. The “Why and how do social networks empower bullying?” section will deal with techno-ethical and epistemological concerns regarding how gossip, mediated by SN, manages to empower cyber-bullying. The “Self-gossip and self-mobbing in the light of the disruption of sub-moralities” section will characterize cyber-bullying as often sparked by self-gossip (soon degrading into self-mobbing) in a scenario where familiar sub-groups, which also mediate defense and mutual understanding, are disrupted. The “Discussion and conclusion” section will consist of a philosophical summary, divided in two parts: a pars destruens analyzing whether SN, in their actual configurations, are fit for being used by humans-like-us, and a pars construens examining the broad potential consequences of highly enforced regulation aimed at contrasting cyber-bullying. [ABSTRACT FROM AUTHOR]

Peers may influence the body image concerns and disordered eating behaviours of adolescent girls through the creation of appearance cultures within friendship cliques. The present study investigates the role of friendship cliques and school gender composition in impacting upon adolescent girls' body image concern and disordered eating behaviours, using hierarchical linear modelling (HLM), a statistical procedure employed in the analysis of nested data. A sample of 156 girls was drawn from four private schools located in the capital city of Western Australia (one single-sex school and three mixed-sex schools). Eighty students from the single-sex school and 76 female students from the mixed-sex schools, comprising 35 friendship cliques, completed questionnaires assessing body image, disordered eating, and a range of variables that have previously been associated with body image concern and disordered eating, including appearance-based social comparison, frequency of appearance-based conversation, appearance-based criticism, friends' concern with thinness, media influence and media pressure. Hierarchical linear modelling analyses found that friendship cliques in all-girls schools exhibited similar levels of body image concern and dieting behaviours, with various peer and other media influence variables accounting for these similarities. Friendship cliques in mixed-sex schools were not found to be similar with regard to body image concern or disordered eating. These findings support the notion that friendship groups can be an important source of influence on the body image concerns of adolescent girls in single-sex schools, and show that both individual and friendship clique level measures of attitudes and behaviours make independent contributions to the prediction of these body image concerns. [ABSTRACT FROM AUTHOR]

A classical model for social-influence-driven opinion change is the threshold model. Here we study cascades of opinion change driven by threshold model dynamics in the case where multiple initiators trigger the cascade, and where all nodes possess the same adoption threshold ø. Specifically, using empirical and stylized models of social networks, we study cascade size as a function of the initiator fractionp.We find that even for arbitrarily high value of ø, there exists a critical initiator fraction pc(ø) beyond which the cascade becomes global. Network structure, in particular clustering, plays a significant role in this scenario. Similarly to the case of single-node or single-clique initiators studied previously, we observe that community structure within the network facilitates opinion spread to a larger extent than a homogeneous random network. Finally, we study the efficacy of different initiator selection strategies on the size of the cascade and the cascade window. [ABSTRACT FROM AUTHOR]

Community detection is widely used in many applications such as social network analysis, collaborative filtering and information retrieval. There are many definitions on community of different characteristics and k-Clique community is the one laying its emphasis on the overlapping between communities. We analyze the association between cohesive subgraph visualization (CSV) plot and k-clique community detection. Then, we propose an algorithm named LargeKCliqueCSV to detect large k-clique communities, which reduces search space through CSV plot. At last, we conduct experiments on Stock Market Data datasets. Experimental results show the good scalability of our algorithm comparing with the state-of-art methods Clique Percolation Method and Sequential Clique Percolation algorithm when k grows large. [ABSTRACT FROM AUTHOR]

We model the forming and dynamics of opinions in a social network with Markov chains. We set and solve, for a number of special cases, the problems of controlling agent opinions and game-theoretic problems of informational conflict. [ABSTRACT FROM AUTHOR]

From the perspective of social exchange theory, we explore the downside of social networking. In particular, we discuss the impact of network properties on cronyism. We identify two types of network, clique and entrepreneurial, and two forms of competition, inter- and intra-network. We argue that network competition generally increases the likelihood of cronyism, and the effect of competition on cronyism is moderated by network type. We outline directions for future research and derive practical implications. [ABSTRACT FROM AUTHOR]

For a (molecular) graph, the first Zagreb index M1 is equal to the sum of squares of the vertex degrees, and the second Zagreb index M2 is equal to the sum of products of degrees of pairs of adjacent vertices. In this paper, we show that all connected graphs with n vertices and k cut edges, the maximum (resp. minimum) M1- and M2-value are obtained, respectively, and uniquely, at K (resp. P), where K is a graph obtained by joining k independent vertices to one vertex of K n− k and P is a graph obtained by connecting a pendent path P k+1 to one vertex of C n− k. [ABSTRACT FROM AUTHOR]

In mammals, access to mates is probably the most important influence on male reproductive success, whereas foraging efficiency is probably the most important influence on female reproductive success Emlen and Oring ( Science 197:215–223,). Male chimpanzees ( Pan troglodytes) are highly gregarious and form cooperative relationships with other males. In contrast, female social relationships vary within and between populations. Females in most East African populations, e.g., Gombe, Mahale, Kibale-Kanyawara, are less gregarious than males and spend most of their time alone or with only their dependent offspring. Researchers have attributed low female gregariousness to the high potential for feeding competition. I provide the first data on association patterns and agonistic interactions of female chimpanzees ( Pan troglodytes schweinfurthii) from the unusually large Ngogo community, Kibale National Park, Uganda. Ngogo females were less gregarious than males, but spent a mean of 64% of their time in association with ≥1 other females and as much time in all-female parties as they did alone. Further, female dyads associated nonrandomly and they formed associative cliques. Association levels within cliques were similar to those among the relatively gregarious West African chimpanzee females at Taï ( Pan troglodytes verus) and among bonobo ( P. paniscus) females. Agonistic interfemale interactions were extremely rare, and monthly mean party size and the numbers of anestrous females per party do not correlate significantly with fruit availability. Thus, Ngogo females maintained relatively high levels of gregariousness, but avoided detrimental feeding competition by preferentially associating with a small subset of other community females. [ABSTRACT FROM AUTHOR]

Peer relationships are commonly thought to be critical for adolescent socialization, including the development of negative health behaviors such as alcohol and tobacco use. The interplay between genetic liability and peer influences on the development of adolescent alcohol and tobacco use was examined using a nationally-representative sample of adolescent sibling pairs and their best friends. Genetic factors, some of them related to an adolescent’s own substance use and some of them independent of use, were associated with increased exposure to best friends with heavy substance use—a gene-environment correlation. Moreover, adolescents who were genetically liable to substance use were more vulnerable to the adverse influences of their best friends—a gene-environment interaction. [ABSTRACT FROM AUTHOR]

This paper reports two prospective investigations of the role of friendship in the relation between peer victimization and grade point averages (GPA). Study 1 included 199 children (105 boys, 94 girls; mean age of 9.1 years) and Study 2 included 310 children (151 boys, 159 girls; mean age of 8.5 years). These children were followed for two school years. In both projects, we assessed aggression, victimization, and friendship with a peer nomination inventory, and we obtained children's GPAs from a review of school records. Peer victimization was associated with academic declines only when children had either a high number of friends who were above the classroom mean on aggression or a low number of friends who were below the classroom mean on aggression. These results highlight the importance of aggression levels among friends for the academic adjustment of victimized children. [ABSTRACT FROM AUTHOR]

We deal with non-rank facets of the stable set polytope of claw-free graphs. We extend results of Giles and Trotter [7] by (i) showing that for any nonnegative integer a there exists a circulant graph whose stable set polytope has a facet-inducing inequality with (a,a+1)-valued coefficients (rank facets have only coefficients 0, 1), and (ii) providing new facets of the stable set polytope with up to five different non-zero coefficients for claw-free graphs. We prove that coefficients have to be consecutive in any facet with exactly two different non-zero coefficients (assuming they are relatively prime). Last but not least, we present a complete description of the stable set polytope for graphs with stability number 2, already observed by Cook [3] and Shepherd [18]. [ABSTRACT FROM AUTHOR]

Clustering applications dealing with perception based or biased data lead to models with non-disjunct clusters. There, objects to be clustered are allowed to belong to several clusters at the same time which results in a fuzzy clustering. It can be shown that this is equivalent to searching all maximal cliques in dynamic graphs like G = ( V,E), where E ⊂ E, t = 1,..., T; E = φ. In this article algorithms are provided to track all maximal cliques in a fully dynamic graph. [ABSTRACT FROM AUTHOR]

Examines transnational ethnic social networks based on ancestral and kinship ties as a form of social capital that facilitates economic growth in a transborder and regional context. Conceptualization of transnational ethnic social capital; Role of transnational ethnic social capital; Insufficiency of transnational ethnic social capital.

Given the growing ethnocultural diversity of Canada's aging population and the increased research focus on the role of the family in the social support of older persons, it is important to explore the ways in which adult ethnic minority children provide assistance to older parents within the context of the family. The current study contributes to research on intergenerational support systems in later life in Japanese Canadian families by examining the factors, particularly the cultural value of oya koh koh (filial obligation), affecting the nature of support from adult children to older parents. Using data gathered from interviews with 100 older nisei (second generation) parents and 100 adult sansei (third generation) children in British Columbia, the study focuses on the frequency, quality and provision of three types of support: emotional, service, and financial. Results of logistic regression analyses indicate that oya koh koh has a significant effect on children's provision of emotional support, but no effect on financial or service support. Parent's health and socioeconomic status are found to have significant effects on children's provision of financial and service support. Child's availability is also a major determinant of financial support. Further, ordinary least squares (OLS) regression analyses results suggest that oya koh koh has a significant effect on the quality of emotional support provided by children to their parents. Findings are discussed in terms of the North American Asian "ideal" family myth and directions for future research. [ABSTRACT FROM AUTHOR]

The article presents two essays related to sociology. Individual within an organizational hierarchy possesses informal and formal connections and ties with others in other organizational hierarchies. The informal connections have their origins in extra-institutional relationships based on such considerations as kinship, membership in fraternal or sororal organizations, old school ties based on graduation from the same educational institution or graduating class, common war-time experiences, common ethnic, migrant, community of origin or religious affiliations, or, relationships established at earlier career stages in offices of other organizations and industries which may be re-invoked at later career stages. The specific characteristic of inter-institutional cliques is that their members' loyalties arise outside the framework of organizational and institutional participation. As networks, inter-institutional cliques have no formal definition of membership but rather share a subliminal recognition of like-mindedness based either on personal attraction or recognition of common personal interest. Such networks have no precise definition of the limits of membership, but rather there are star members and peripheral members who have interlocking memberships in other networks surrounding other star members: star members are those who control resources, jobs and other forms of opportunity for clique members.

This paper focuses on one type of linkage among firms, that is, subgroups based on other types of linkage, such as communication, conflict and market relations. Subgroups of organizations within larger interorganizational networks such as distribution channels represent an important focus of attention. Subgroups may represent loci of power and bases of competition in a channel that affect channel functioning. Such subgroups may not be readily identifiable from an examination of individual firm characteristics but stem from the patterns of relations among the firms. Subgroups of firms, also termed as subsystems or cliques in this article, are sets of firms within a channel system that have stronger links with each other than they have with other channel members. Many methods have been developed for identifying subgroups. In this paper two important methods are described and used to examine the pattern of subgroups existing in an actual distribution channel.

Based on data collected in the course of the September and November 1980 waves of the National Election Studies, this contextual analysis of interpersonal relations in social net- works presents two major findings: First, the neighborhood as a geographical unit does not appear to be a perceptually salient environment for political behavior; and second, particular neighbors. individually linked to a voter, appear to constitute a social network that has an independent impact on partisan affect for the political parties and their candidates as well as on stability or change in vote preferences as the electoral season goes forward. Thus, although the neighborhood appears to be of minor importance as a political environment, social relations among particular neighbors result in an interpersonal context that has an impact on political behavior. [ABSTRACT FROM AUTHOR]

Massive graphs are ubiquitous and at the heart of many real-world problems and applications ranging from the World Wide Web to social networks. As a result, techniques for compressing graphs have become increasingly important and remains a challenging and unsolved problem. In this work, we propose a graph compression and encoding framework called GraphZIP based on the observation that real-world graphs often form many cliques of a large size. Using this as a foundation, the proposed technique decomposes a graph into a set of large cliques, which is then used to compress and represent the graph succinctly. In particular, disk-resident and in-memory graph encodings are proposed and shown to be effective with three important benefits. First, it reduces the space needed to store the graph on disk (or other permanent storage device) and in-memory. Second, GraphZIP reduces IO traffic involved in using the graph. Third, it reduces the amount of work involved in running an algorithm on the graph. The experiments demonstrate the scalability, flexibility, and effectiveness of the clique-based compression techniques using a collection of networks from various domains. [ABSTRACT FROM AUTHOR]