Radosław Michalski

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• Ph.D. D.Sc.
• Associate Professor at Wrocław University of Science and Technology

The term blockchain has its roots in cryptocurrencies. However, its applications are now more widespread, and in many areas, this technology has become the foundation of the distributed ledger. The blockchain protocol assumes that all the participants of the system are both contributors and safeguards of this ledger, since the lack of a trusted thi...

Human relations are driven by social events—people interact, exchange information, share knowledge and emotions, and gather news from mass media. These events leave traces in human memory, the strength of which depends on cognitive factors such as emotions or attention span. Each trace continuously weakens over time unless another related event act...

One important task in the study of information cascade is to predict the future recipients of a message given its past spreading trajectory. While the network structure serves as the backbone of the spreading, an accurate prediction can hardly be made without the knowledge of the dynamics on the network. The temporal information in the spreading se...

This work develops the concept of the temporal network epistemology model enabling the simulation of the learning process in dynamic networks. The results of the research, conducted on the temporal social network generated using the CogSNet model and on the static topologies as a reference, indicate a significant influence of the network temporal d...

Mobile phones contain a wealth of private information, so we try to keep them secure. We provide large-scale evidence that the psychological profiles of individuals and their relations with their peers can be predicted from seemingly anonymous communication traces – calling and texting logs that service providers routinely collect. Based on two ext...

Typically, for analysing and modelling social phenomena, networks are a convenient framework that allows for the representation of the interconnectivity of individuals. These networks are often considered transmission structures for processes that happen in society, e.g. diffusion of information, epidemics, and spread of influence. However, constru...

Temporality, a crucial characteristic in the formation of social relationships, was used to quantify the long-term time effects of networks for link prediction models, ignoring the heterogeneity of time effects on different time scales. In this work, we propose a novel approach to link prediction in temporal networks, extending existing methods wit...

With the advancement of computational network science, its research scope has significantly expanded beyond static graphs to encompass more complex structures. The introduction of streaming, temporal, multilayer, and hypernetwork approaches has brought new possibilities and imposed additional requirements. For instance, by utilising these advanceme...

Understanding the mechanisms behind opinion formation is crucial for gaining insight into the processes that shape political beliefs, cultural attitudes, consumer choices, and social movements. This work aims to explore a nuanced model that captures the intricacies of real-world opinion dynamics by synthesizing principles from cognitive science and...

Temporality, a crucial characteristic in the formation of social relationships, was used to quantify the long-term time effects of networks for link prediction models, ignoring the heterogeneity of time effects on different time scales. In this work, we propose a novel approach to link prediction in temporal networks, extending existing methods wit...

With the advancement of computational network science, its research scope has significantly expanded beyond static graphs to encompass more complex structures. The introduction of streaming, temporal, multilayer, and hypernetwork approaches has brought new possibilities and imposed additional requirements. For instance, by utilising these advanceme...

Interaction with others influences our opinions and behaviours. Our activities within various social circles lead to different opinions expressed in various situations, groups, and ways of communication. Earlier studies on agent-based modelling of conformism within networks were based on a single-layer approach. Contrary to that, in this work, we p...

This work develops the concept of temporal network epistemology model enabling the simulation of the learning process in dynamic networks. The results of the research, conducted on the temporal social network generated using the CogSNet model and on the static topologies as a reference, indicate a significant influence of the network temporal dynam...

One important task in the study of information cascade is to predict the future recipients of a message given its past spreading trajectory. While the network structure serves as the backbone of the spreading, an accurate prediction can hardly be made without the knowledge of the dynamics on the network. The temporal information in the spreading se...

Multilayer networks are the underlying structures of multiple real-world systems where we have more than one type of interaction/relation between nodes: social, biological, computer, or communication, to name only a few. In many cases, they are helpful in modeling processes that happen on top of them, which leads to gaining more knowledge about the...

With the appearance of cryptocurrencies more than ten years back, many have been thinking that it is rather a short-term novelty that would only interest few enthusiasts and die shortly after. The history, however, has shown that not only cryptocurrencies itself are alive, but also the blockchain technology started to be applied in a variety of dom...

The spread of influence in networks is a topic of great importance in many application areas. For instance, one would like to maximise the coverage, limiting the budget for marketing campaign initialisation and use the potential of social influence. To tackle this and similar challenges, more than a decade ago, researchers started to investigate th...

Complex networks are the underlying structures of multiple real-world systems: social, biological, computer, or communication, to name only a few. In many cases, they are helpful in modelling processes that happen on top of them, which leads to gaining more knowledge about these phenomena. One example of such a process is the spread of influence. H...

It is not news that our mobile phones contain a wealth of private information about us, and that is why we try to keep them secure. But even the traces of how we communicate can also tell quite a bit about us. In this work, we start from the calling and texting history of 200 students enrolled in the Netsense study, and we link it to the type of re...

The spread of influence in networks is a topic of great importance in many application areas. For instance, one would like to maximise the coverage, limiting the budget for marketing campaign initialisation and use the potential of social influence. To tackle this and similar challenges, more than a decade ago, researchers started to investigate th...

Seed selection is one of the key factors influencing information spread within networks. Whereas most solutions are based on single-stage seeding at the beginning of the process, performance increases when additional seeds are used. This enables the acquisition of knowledge about ongoing processes and activating new nodes for further influence maxi...

The challenge of influence maximization in social networks is tackled in many settings and scenarios. However, the most explored variant is looking at how to choose a seed set of a given size, that maximizes the number of activated nodes for selected model of social influence. This has been studied mostly in the area of static networks, yet other k...

Formation of a hierarchy within an organization is a natural way of assigning the duties, delegating responsibilities and optimizing the flow of information. Only for the smallest companies the lack of the hierarchy, that is, a flat one, is possible. Yet, if they grow, the introduction of a hierarchy is inevitable. Most often, its existence results...

Formation of a hierarchy within an organization is a natural way of optimizing the duties, responsibilities and flow of information. Only for the smallest organizations the lack of the hierarchy is possible, yet, if they grow, its appearance is inevitable. Most often, its existence results in a different nature of the tasks and duties of its member...

The social influence maximization problem is an important research topic for many years since it has a tremendous impact on society. As social influence can be maximized for many purposes, such as marketing, politics, spreading innovations, there are many stakeholders interested in progress in this area. As it has been shown, for most settings find...

Human communication is commonly represented as a temporal social network, and evaluated in terms of its uniqueness. We propose a set of new entropy-based measures for human communication dynamics represented within the temporal social network as event sequences. Using real world datasets and random interaction series of different types we find that...

Usually, the launch of the diffusion process is triggered by a few early adopters–i.e., seeds of diffusion. Many studies have assumed that all seeds are activated once to initiate the diffusion process in social networks and therefore are focused on finding optimal ways of choosing these nodes according to a limited budget. Despite the advances in...

Supporting information file with proofs, additional analysis, Figs A-G, Tables A-C and detailed statistics. (PDF)

Data file with used networks and detailed results. (ZIP)

We consider here information spread which propagates with certain probability from nodes just activated to their not yet activated neighbors. Diffusion cascades can be triggered by activation of even a small set of nodes. Such activation is commonly performed in a single stage. A novel approach based on sequential seeding is analyzed here resulting...

We consider here information spread which propagates with certain probability from nodes just activated to their not yet activated neighbors. Diffusion cascades can be triggered by activation of even a small set of nodes. Such activation is commonly performed in a single stage. A novel approach based on sequential seeding is analyzed here resulting...

Human relations are driven by social events - people interact, exchange information, share knowledge and emotions, or gather news from mass media. These events leave traces in human memory. The initial strength of a trace depends on cognitive factors such as emotions or attention span. Each trace continuously weakens over time unless another relate...

Human communication is commonly represented as a temporal social network, and evaluated in terms of its uniqueness. We propose a set of new entropy-based measures for human communication dynamics represented within the temporal social network as event sequences. Using real world datasets and random interaction series of different types we find that...

Information spreading in complex networks is often modeled as diffusing information with certain probability from nodes that possess it to their neighbors that do not. Information cascades are triggered when the activation of a set of initial nodes – seeds – results in diffusion to large number of nodes. Here, several novel approaches for seed init...

Presented data contains the record of five spreading campaigns that occurred in a virtual world platform. Users distributed avatars between each other during the campaigns. The processes varied in time and range and were either incentivized or not incentivized. Campaign data is accompanied by events. The data can be used to build a multilayer netwo...

Seeding strategies for influence maximization in social networks have been studied for more than a decade. They have mainly relied on the activation of all resources (seeds) simultaneously in the beginning; yet, it has been shown that sequential seeding strategies are commonly better. This research focuses on studying sequential seeding with buffer...

Seeding strategies for influence maximization in social networks have been studied for more than a decade. They have mainly relied on the activation of all resources (seeds) simultaneously in the beginning; yet, it has been shown that sequential seeding strategies are commonly better. This research focuses on studying sequential seeding with buffer...

Initialization of information spreading processes within complex networks is usually based on selection of initial nodes as a seed set. While most methods are choosing seeds in a single stage, another possible option is a partial budget usage in the first stage and spending the remaining budget while the process develops. In this paper we analyze h...

Objective: The Learning Health System (LHS) requires integration of research into routine practice. eSource or embedding clinical trial functionalities into routine electronic health record (EHR) systems has long been put forward as a solution to the rising costs of research. We aimed to create and validate an eSource solution that would be readily...

Campaigns based on information spreading processes within online networks have become a key feature of marketing landscapes. Most research in the field has concentrated on propagation models and improving seeding strategies as a way to increase coverage. Proponents of such research usually assume selection of seed set and the initialization of the...

Objective The Learning Health System (LHS) requires integration of research into routine practice. ‘eSource’ or embedding clinical trial functionalities into routine electronic health record (EHR) systems has long been put forward as a solution to the rising costs of research. We aimed to create and validate an eSource solution that would be readil...

Presented data contains the record of five spreading campaigns that occurred in a virtual world platform. During this campaigns, users were about distributing the avatars between each other. The processes were either incentivized or not incentivized, and varying in time and range. The campaign data is accompanied by the events that can be used to b...

The implementation of new methods that increase the quality and effectiveness of research processes became an unique advantage to online social networking sites. Conducting accurate and meaningful surveys is one of the most important facets for research, wherein the representativeness of selected online samples is often a challenge and the results...

The task of determining labels of all network nodes based on the knowledge about network structure and labels of some training subset of nodes is called the within-network classification. It may happen that none of the labels of the nodes is known and additionally there is no information about number of classes to which nodes can be assigned. In su...

The problem of finding optimal set of users for influencing others in social networks has been studied for more than ten years. As it has been shown, it is a NP-hard problem, so since than some heuristics were proposed as suboptimal solutions. Still, one of the commonly used assumption is the one that seeds are chosen on the static network, not the...

Computations related to learning processes within an organizational social network area require some network model preparation and specific algorithms for implementing human behaviors in simulated environments. The proposals in this research model of collaborative learning in an organizational social network are based on knowledge resource distribu...

The uniqueness of online social networks makes it possible to implement new methods that increase the quality and effectiveness of research processes. While surveys are one of the most important tools for research, the representativeness of selected online samples is often a challenge and the results are hardly generalizable. An approach based on s...

The following chapter aims to present the current research in the area of modelling and maximizing social influence in networks. Apart from describing the most popular models for this process, it focuses on presenting the advances in maximizing the spread of influence in social networks . Since most of the research was suited for static networks ca...

The enormous popularity of the Internet and the evolution of social media create new areas for observing and modelling processes related to social sciences, such as social influence or diffusion of innovations. Now it is possible to evaluate different strategies of targeting people and observing the outcome of the process, since social graphs and s...

The problem of finding optimal set of users for influencing others in the social network has been widely studied. Because it is NP-hard, some heuristics were proposed to find sub-optimal solutions. Still, one of the commonly used assumption is the one that seeds are chosen on the static network, not the dynamic one. This static approach is in fact...

Humans utilise multiple communication channels in their social interactions and also information diffusion as well as the spread of influence are practically related with many contexts. Each such context (channel) may represent a different communication method or a different environment of a given person. This facilitates building multiple social n...

Modelling the diffusion of information is one of the key areas related to activity within social networks. In this field, there is recent research associated with the use of community detection algorithms and the analysis of how the structure of communities is affecting the spread of information. The purpose of this article is to examine the mechan...

In relational learning tasks such as within network classification the main problem arises from the inference of nodes' labels based on the the ground true labels of remaining nodes. The problem becomes even harder if the nodes from initial network do not have any labels assigned and they have to be acquired. However, labels of which nodes should b...

Diffusion of information in social networks takes more and more attention from marketers. New methods and algorithms are constantly developed towards maximizing reach of the campaigns and increasing their effectiveness. One of the important research directions in this area is related to selecting initial nodes of the campaign to result with maximiz...

The main goal of the paper is to present how the data-driven approach to social network analysis enables various applications of knowledge about human behaviour. Three main illustrative application domains are pointed out and briefly analysed: social recommender systems in online multimedia publishing services, assessment of organisational structur...

The dynamic character of most social networks requires to model evolution of networks in order to enable complex analysis of theirs dynamics. The following paper focuses on the definition of differences between network snapshots by means of Graph Differential Tuple. These differences enable to calculate the diverse distance measures as well as to i...

Viral campaigns on the Internet may follow variety of models, depending on the content, incentives, personal attitudes of sender and recipient to the content and other factors. Due to the fact that the knowledge of the campaign specifics is essential for the campaign managers, researchers are constantly evaluating models and real-world data. The go...

Authors propose a conceptual model of participation in viral diffusion process composed of four stages: awareness, infection, engagement and action. To verify the model it has been applied and studied in the virtual social chat environment settings. The study investigates the behavioral paths of actions that reflect the stages of participation in t...

Viral campaigns are crucial methods for word-of-mouth marketing in social communities. The goal of these campaigns is to encourage people for activity. The problem of incentivised and non-incentivised campaigns is studied in the paper. Based on the data collected within the real social networking site both approaches were compared. The experimental...

The dynamic character of most social networks requires to model evolution of networks in order to enable complex analysis of theirs dynamics. The following paper focuses on the definition of differences between network snapshots by means of Graph Differential Tuple. These differences enable to calculate the diverse distance measures as well as to i...

Diffusion of information and viral content, social contagion and influence are still topics of broad evaluation. As theory explaining the role of influentials moves slightly to reduce their importance in the propagation of viral content, authors of the following paper have studied the information epidemic in a social networking platform in order to...

The link prediction problem in social networks defined as a task to predict whether a link between two particular nodes will appear in the future is still a broadly researched topic in the field of social network analysis. However, another relevant problem is solved in the paper instead of individual link forecasting: prediction of key network meas...

Social network analysis provides helpful reports and comparisons, which may support the corporate human resources management. Several ideas, measurements, interpretations and evaluation methods are presented and discussed in the chapter, in particular group detection, centrality degree, location analysis, process management support, dynamic analysi...

The paper provides the overview of essential analyses and methods, helpful for enterprise architecture improvement and based on social network approach. The ideas presented in this paper focus on social network, that is built with the use of real-life manufacturing company data. It has been shown that corporate social network analysis, as a decisio...

The following paper presents the concept of matching social network and corporate hierarchy in organizations with stable corporate structure. The idea allows to confirm whether social position of an employee calculated on the basis of the social network differs significantly from the formal employee role in the company. The results of such analysi...

Most of the real social networks extracted from various data sources evolve and change their profile over time. For that reason, there is a great need to model evolution of networks in order to enable complex analyses of theirs dynamics. The model presented in the paper focuses on definition of differences between following network snapshots by mea...

Social network analysis provides helpful reports and comparisons, which may support the corporate human resources management. Several ideas, measurements, interpretations and evaluation methods are presented and discussed in the chapter, in particular group detection, centrality degree, location analysis, process management support, dynamic analysi...