Discovering Influential Nodes for SIS Models in Social Networks

A social network is a collection of social entities and the relations among them. Collection and sharing of such network data for analysis raise significant privacy concerns for the involved individuals, especially when human users are involved. To address such privacy concerns, several techniques, such as k-anonymity based approaches, have been proposed in the literature. However, such approaches introduce a large amount of distortion to the original social network graphs, thus raising serious questions about their utility for useful social network analysis. Consequently, these techniques may never be applied in practice. In this paper, we emphasize the use of network structural semantics in the social network analysis theory to address this problem. We propose an approach for enhancing anonymization techniques that preserves the structural semantics of the original social network by using the notion of roles and positions. We present experimental results that demonstrate that our approach can significantly help in preserving graph and social network theoretic properties of the original social networks, and hence improve utility of the anonymized data.

This study sampled 24 interviews of Vietnamese Female Spouses living in Nantou. Interview and observation are used to realize their social network formation after they came to Taiwan. The social network was either duplication as their original community or a new multicultural group? Which one is more helpful for them? Besides, based on their social relationship, the study tried to explain why most of their friends are Vietnamese. This study found that the Vietnamese female spouses copied their original social network. Most members met at works and offered them great support. It proved that the brides have small, similar and closed social relationship in Taiwan. Ethnicity and class are two important factors, which influenced on their social network development.

Identifying the most influential individuals can provide invaluable help in developing and deploying effective viral marketing strategies. Previous studies mainly focus on designing efficient algorithms or heuristics to find top-K influential nodes on a given static social network. While, as a matter of fact, real-world social networks keep evolving over time and a recalculation upon the changed network inevitably leads to a long running time, significantly affecting the efficiency. In this paper, we observe from real-world traces that the evolution of social network follows the preferential attachment rule and the influential nodes are mainly selected from high-degree nodes. Such observations shed light on the design of IncInf, an incremental approach that can efficiently locate the top-K influential individuals in evolving social networks based on previous information instead of calculation from scratch. In particular, IncInf quantitatively analyzes the influence spread changes of nodes by localizing the impact of topology evolution to only local regions, and a pruning strategy is further proposed to effectively narrow the search space into nodes experiencing major increases or with high degrees. We carried out extensive experiments on real-world dynamic social networks including Facebook, NetHEPT, and Flickr. Experimental results demonstrate that, compared with the state-of-the-art static heuristic, IncInf achieves as much as 21\(\times \) speedup in execution time while maintaining matching performance in terms of influence spread.

Viral marketing is widely used by businesses to achieve their marketing objectives using social media. In this work, we propose a customized crowdsourcing approach for viral marketing which aims at efficient marketing based on information propagation through a social network. We term this approach the social community-based crowdsourcing platform and integrate it with an information diffusion model to find the most efficient crowd workers. We propose an intelligent viral marketing framework (IVMF) comprising two modules to achieve this end. The first module identifies the K-most influential users in a given social network for the platform using a novel linear threshold diffusion model. The proposed model considers the different propagation behaviors of the network users in relation to different contexts. Being able to consider multiple topics in the information propagation model as opposed to only one topic makes our model more applicable to a diverse population base. Additionally, the proposed content-based improved greedy (CBIG) algorithm enhances the basic greedy algorithm by decreasing the total amount of computations required in the greedy algorithm (the total influence propagation of a unique node in any step of the greedy algorithm). The highest computational cost of the basic greedy algorithm is incurred on computing the total influence propagation of each node. The results of the experiments reveal that the number of iterations in our CBIG algorithm is much less than the basic greedy algorithm, while the precision in choosing the K influential nodes in a social network is close to the greedy algorithm. The second module of the IVMF framework, the multi-objective integer optimization model, is used to determine which social network should be targeted for viral marketing, taking into account the marketing budget. The overall IVMF framework can be used to select a social network and recruit the K-most influential crowd workers. In this paper, IVMF is exemplified in the domain of personal care industry to show its importance through a real-life case.

A most influential node group discovery method for influence maximization in social networks: A trust-based perspective

A social network is a set of relationships and interactions among social entities such as individuals, organizations, and groups. The social network analysis is one of the major topics in the ongoing research field. The major problem regarding the social network is finding the most influential objects or persons. Identification of most influential nodes in a social network is a tedious task as large numbers of new users join the network every day. The most commonly used method is to consider the social network as a graph and find the most influential nodes by analyzing it. The degree centrality method is node based and has the advantage of easy identification of most influential nodes. In this paper a method called "Enhanced Degree Centrality Measure" is proposed which integrates clustering co-efficient value along with node based degree centrality. The enhanced degree centrality measure is applied to three different datasets which are obtained from the Facebook to analyze the performance. The response obtained is compared with existing methods such as degree centrality method and SPIN algorithm. By comparison, it is found that highest number of active nodes identified by the proposed method is 64 when compared with SPIN algorithm which identifies only 55.

Even though social networks provide nice ways for people to become very connected, some people end up feeling that they have a lack of meaningful, significant relationships. I think the answer is simple. I believe that the best way to connect with people and form relationships is through the original social network: hanging out in person with people who have similar interests.

The influence propagation between the nodes is the key research area for detecting the online communities in the available dense social network. The analysis of influence propagation with time series analysis and measuring the centrality between the nodes will significantly increase the metrics of social network. The source node is dedicated to find the required information about the node links. The empirical results were discussed in this paper. Betweenness and centrality of influential node prorogation has identified users in the community and analyzes how the information has exchanged with different time ranges. With unsupervised learning, time ranges are analyzed between 0.5s and 1s in the strong ties of the influential propagation node, and further the influential node relationship between the communities has been calculated by using the strong and weak links. We collect the user information on the online social network-facebook user data, performing some actions post, comments, share, tag, Hit Rate, and the time. From these we have analyzed the propagation between the pair of nodes and users community. It is observed that the influence propagation in the collected data, at a time ’t’ the node U1 which is a ego node of U2, the information was shared between them, if the interaction has performed in a symmetric manner, say at a time $t+\beta$, the action is propagated from U2 to U1. We observed that the interaction of the frequency of action with different content, U2 is indeed exerting the influence on U1. The dependency of discriminate paths was identified and compared with the results obtained from random walk model to deliver a satisfied result by using the proposed model.

Identifying influential nodes is one of the basic issues in managing large social networks. Identifying influence nodes in social networks and other networks, including transportation, can be effective in applications such as identifying the sources of spreading rumors, making advertisements more effective, predicting traffic, predicting diseases, etc. Therefore, it will be important to identify these people and nodes in social networks from different aspects. In this article, a new method is presented to identify influential nodes in the social network. The proposed method utilizes the combination of users’ social characteristics and their reaction information to identify influential users. Since the identification of these users in the large social network is a complex process and requires high processing power and time, clustering and identifying communities have been used in the proposed method to reduce the complexity of the problem. In the proposed method, the structure of the social network is divided into its constituent communities and thus the problem of identifying influential nodes (in the entire network) turns into several problems of identifying an influential node (in each community). The suggested method for predicting the nodes first predicts the links that may be created in the future and then identifies the influential nodes based on an iterative strategy. The proposed algorithm uses the criteria of centrality and influence domain to identify this category of users and performs the identification process both at the community and network levels. The efficiency of the method has been evaluated using real databases and the results have been compared with previous works. The results demonstrate that the proposed method provides a more suitable performance in detecting the influential nodes and is superior in terms of accuracy, recall and processing time.

In recent years, social networks have become an integral part of people's lives and play a significant role in the real world.The primary aim of influence maximization problem is finding a set of nodes in the network which can maximize the influence if the diffusion process starts from them.Therefore, the problem's goal is to find influential people in large scale real social networks.The penetration phenomenon is carried out according to an influence model in the network.Two independent cascade and linear threshold influence models, the most common of which is the independent cascade model, are utilized for broadcasting in the network.Theoreticaly, optimizing the selection influential nodes problem is NP-hard in both models.The problem will start by considering the social network's graph, a specific influence model and a given number k.The problem's goal is to select k nodes (users) from the graph (network) as influential nodes, so that the number of active nodes is maximized at the end of the diffusion process.Due to the influence 4 62 30 maximization problem and finding influential people is an NP-hard optimization problem in the social network, meta-heuristic algorithms can be used to solve the problem.With regard to the privous researches, there is just one objective function as the problem's goal and it is maximizing the number of effective nodes of the diffusion model.While other objective functions such as maximizing the number of effective nodes in the diffusion model and minimizing the budget value k (the number of initial nodes as seed) are not considered, minimizing the time required for effective diffusion can be achieved by having k initial nodes.Although various models for the problem and various optimization algorithms have been presented to discover influential nodes in social networks, paying attention to the multi-objective nature of the problem and improving the performance of the proposed optimization algorithms are a serious research challenge in this field.In this paper.A fuzzy version of the NSGA-II as a multi-objective genetic algorithm, whose mutation and crossover rates are adjusted by Fuzzy Inference System, is utilized to simultaneously optimize the three objectives of maximizing the number of effective nodes, minimizing the number of initial nodes and minimizing the required diffusion time.In the proposed method, the Expected Diffusion Value (EDV) of the diffusion model is replaced instead the simulation of the independent cascade diffusion model with heavy calculations to calculate the diffusion spread (the number of effective nodes of the diffusion model).Therefore, the EDV function is satisfied as the thied objective (minimizing the required diffusion time).The second objective function can also be converted into a maximization function by considering N-k nodes, where k is the number of selected initial nodesand N is the total graph nodes.The decimal numerical coding with fixed length is used in the proposed method.Based on the coding, each chromosome has k genes in the search space.The integer part of each gene is the selected node number.The decimal part is also used to determine whether that initial node exists or not.In the maximizing influence process using the fuzzy NSGA-II algorithm, the solution space (chromosomes) consists of k number of initial nodes, which should be encoded into the fuzzy NSGA-II comprehensible space.Also, a Fuzzy Inference System is proposed to adjust the mutation and recombination rates for filling up a serious challenge of genetic algorithms.In the fuzzy system, NF and FitBest are considered as two input variables, and Pm (mutation rate) and Pc (crossover rate) are returned as outputs NF is the number of chromosomes in the first frontier (F1) of the multi-objective genetic algorithm and FitBest is the average of the normalized objective functions for the chromosomes in F1.To analysis the efficiency of the proposed method, the obtained exprimental results have been compared with conventional maximizing influence methods, i.e., degree centrality, distance centrality, closeness centerality, betweenness, eigenvector and page rank methods, non-fuzzy version of NSGA-II, the latest methods presented for maximizing penetration based on multi-objective meta-heuristic algorithms, i.e. GP multi-objective evolutionary algorithm, multi-objective crow search algorithm (MOCSA), greedy randomized adaptive search process algorithm (GRASP) and the Multi-Transformation Evolutionary Framework (MTEF) on five benchmark graph datasets Arenasjazz, Canetscience, EgoFacebook, Higgs-Reply and Slashdot.This comparison is based on four criteria: EDV, cost (the number of nodes selected as seed), the influence expansion criterion (s), i.e. the number of active nodes with the independent cascade (IC) propagation model, and the execution time of the method in seconds.The obtained results show the superiority of the proposed method over the other methods.

This dissertation consists of two original studies in social networks and one original study in political economy. In the first two chapters, I study (i) how social networks form, and (ii) how economic agents optimize their behaviors for a given network structure. In the last chapter, I examine how election rules affect individual voting decisions and ultimate election outcomes. In Chapter 1, Social Network Formation and Strategic Interaction in Large Networks, I present a dynamic network formation model that aims to explain why some empirical degree distributions exhibit the increasing hazard rate property (IHRP). In my model, a sequentially arriving node forms a link with one existing node through a bilateral agreement. newborn node prefers a highly linked node; however, the more links an existing node has, the more the marginal return from an additional link diminishes. I prove that the IHRP emerges if and only if the latter effect prevails over the former. I present two implications of the IHRP for strategic interactions in networks. First, when there is uncertainty about neighboring agents' connectivity, the IHRP guarantees that a unique Bayesian equilibrium exists in a network game with strategic complementarities. Second, the IHRP characterizes a monotone revenue-maximizing mechanism with allocative externalities. In Chapter 2, Monopoly Pricing and Diffusion of a (Social) Network Good, I present a model of dynamic pricing and diffusion of a network good sold by a monopolist. In the model, the network good is a subscription social network good. This means that in each period, each consumer has to pay a subscription price to use the good, and the utility derived from subscribing to the good increases as more of her neighboring consumers subscribe. Consumers myopically optimize their subscription decisions, and the monopolist chooses a sequence of subscription prices that maximizes his discounted sum of per-period profits. Three main results emerge. First, I characterize a unique steady state of the monopoly market. Second, I find that optimal sequences of subscription prices oscillate around the subscription price at the steady state as time passes. Third, I analyze how changes in the monopolist's discount factor and the density of the social network affect the subscription price, subscription rate, and deadweight loss at the steady state. In Chapter 3, A Model of Pre-Electoral Coalition Formation, I study how two different election rules, simple plurality (e.g., as in South Korea) and two-round runoff (e.g., as in France), affect political candidates’ incentives to form pre-electoral coalitions (PECs). In my model, three candidates compete for a single office, and two candidates can form a PEC. Since the candidates are both policy- and office-motivated, one candidate can incentivize the other candidate to withdraw his candidacy by choosing a joint policy platform. I find that PECs are more likely to form in plurality elections than in two-round runoff elections. I further examine how other electoral environments, such as ideological distance and pre-election polls, influence incentives to form PECs.

Ranking nodes in complex networks based on local structure and improving closeness centrality

Finding a number of nodes that are able to maximize the spread of influence through the social network and are called influence maximization has numerous applications in marketing. One such application is to find influential members for promoting a product across a large network. Even though numerous algorithms have been proposed, challenges such as scalability, time constraints, and low accuracy have motivated the researchers for better solutions. Some of the newly proposed algorithms are scalable, but fail to provide adequate accuracy. On the other hand, some greedy algorithms provide a good level of accuracy but are very time consuming for large networks. In this paper, an algorithm is proposed called FAIMCS that can quickly find influential nodes across large networks with high accuracy. FAIMCS, reduces computational overhead considerably by eliminating major portions of the social network graph which have little influence. FAIMCS uses community detection algorithm to determine each community's quota of influential nodes based on the structure of that community. Finally, it obtains influential nodes from the candidate nodes. Experiment results show FAIMCS is faster than current algorithms and provides a high level of accuracy for large social networks.

To research rumor diffusion in social friend network, based on interests, a dynamic friend network is proposed, which has the characteristics of clustering and community, and a diffusion model is also proposed. With this friend network and rumor diffusion model, based on the zombie-city model, some simulation experiments to analyze the characteristics of rumor diffusion in social friend networks have been conducted. The results show some interesting observations: (1) positive information may evolve to become a rumor through the diffusion process that people may modify the information by word of mouth; (2) with the same average degree, a random social network has a smaller clustering coefficient and is more beneficial for rumor diffusion than the dynamic friend network; (3) a rumor is spread more widely in a social network with a smaller global clustering coefficient than in a social network with a larger global clustering coefficient; and (4) a network with a smaller clustering coefficient has a larger efficiency.

Social networks are attracting significant interest from researchers in different domains, especially with the advent of social networking systems which enable large-scale collection of network information. However, as much as analysis of such social networks can benefit researchers, it raises serious privacy concerns for the people involved in them. To address such privacy concerns, several techniques, such as k-anonymity-based approaches, have been proposed in the literature to provide user anonymity in published social networks. However, these methods usually introduce a large amount of distortion to the original social network graphs, thus, raising serious questions about their utility for useful social network analysis. Consequently, these techniques may never be applied in practice. We propose two methods to enhance edge-perturbing anonymization methods based on the concepts of structural roles and edge betweenness in social network theory. We experimentally show significant improvements in preserving structural properties in an anonymized social network achieved by our approach compared to the original algorithms over several data sets.