A semi-supervised approach to visualizing and manipulating overlapping communities

When evaluating a network topology, occasionally data structures cannot be segmented into absolute, heterogeneous groups. There may be a spectrum to the dataset that does not allow for this hard clustering approach and may need to segment using fuzzy/overlapping communities or cliques. Even to this degree, when group members can belong to multiple cliques, there leaves an ever present layer of doubt, noise, and outliers caused by the overlapping clustering algorithms. These imperfections can either be corrected by an expert user to enhance the clustering algorithm or to preserve their own mental models of the communities. Presented is a visualization that models overlapping community membership and provides an interactive interface to facilitate a quick and efficient means of both sorting through large network topologies and preserving the user's mental model of the structure. © 2013 IEEE

A bitwise clique detection approach for accelerating power graph computation and clustering dense graphs

Graphs are at the essence of many data representations. The visual analytics over graphs is usually difficult due to their size, which makes their visual display challenging, and their fundamental algorithms, which are often classified as NP-hard problems. The Power Graph Analysis (PGA) is a method that simplifies networks using reduced representations for complete subgraphs (cliques) and complete bipartite subgraphs (bicliques), in both cases with edge reductions. The benefits of a power graph are the preservation of information and its capacity to show essential information about the original network. However, finding an optimal representation (maximum edges reduction) is also an NPhard problem. In this work, we propose BCD, a greedy algorithm that uses a Bitwise Clique Detection approach to finding power graphs. BCD is faster than competing strategies and allows the analysis of bigger graphs. For the display of larger power graphs, we propose an orthogonal layout to prevent overlapping of edges and vertices. Finally, we describe how the structure induced by the power graph is used for clustering analysis of dense graphs. We demonstrate with several datasets the results obtained by our proposal and compare against competing strategies.Os grafos são essenciais para muitas representações de dados. A análise visual de grafos é usualmente difícil devido ao tamanho, o que representa um desafio para sua visualização. Além de isso, seus algoritmos fundamentais são frequentemente classificados como NP-difícil. Análises dos grafos de potência (PGA em inglês) é um método que simplifica redes usando representações reduzidas para subgrafos completos chamados cliques e subgrafos bipartidos chamados bicliques, em ambos casos com una redução de arestas. Os benefícios da representação de grafo de potência são a preservação de informação e a capacidade de mostrar a informação essencial sobre a rede original. Entretanto, encontrar uma representação ótima (a máxima redução de arestas possível) é também um problema NP-difícil. Neste trabalho, propomos BCD, um algoritmo guloso que usa um abordagem de detecção de bicliques baseado em operações binarias para encontrar representações de grafos de potencia. O BCD é mas rápido que as estratégias atuais da literatura. Finalmente, descrevemos como a estrutura induzida pelo grafo de potência é utilizado para as análises dos grafos densos na detecção de agrupamentos de nodos

Defining the Minimum Security Baseline in a Multiple Security Standards Environment by Graph Theory Techniques

One of the best ways to protect an organization’s assets is to implement security requirements defined by different standards or best practices. However, such an approach is complicated and requires specific skills and knowledge. In case an organization applies multiple security standards, several problems can arise related to overlapping or conflicting security requirements, increased expenses on security requirement implementation, and convenience of security requirement monitoring. To solve these issues, we propose using graph theory techniques. Graphs allow the presentation of security requirements of a standard as graph vertexes and edges between vertexes, and would show the relations between different requirements. A vertex cover algorithm is proposed for minimum security requirement identification, while graph isomorphism is proposed for comparing existing organization controls against a set of minimum requirements identified in the previous step

Informacijos saugos reikalavimų harmonizavimo, analizės ir įvertinimo automatizavimas

The growing use of Information Technology (IT) in daily operations of enterprises requires an ever-increasing level of protection over organization’s assets and information from unauthorised access, data leakage or any other type of information security breach. Because of that, it becomes vital to ensure the necessary level of protection. One of the best ways to achieve this goal is to implement controls defined in Information security documents. The problems faced by different organizations are related to the fact that often, organizations are required to be aligned with multiple Information security documents and their requirements. Currently, the organization’s assets and information protection are based on Information security specialist’s knowledge, skills and experience. Lack of automated tools for multiple Information security documents and their requirements harmonization, analysis and visualization lead to the situation when Information security is implemented by organizations in ineffective ways, causing controls duplication or increased cost of security implementation. An automated approach for Information security documents analysis, mapping and visualization would contribute to solving this issue. The dissertation consists of an introduction, three main chapters and general conclusions. The first chapter introduces existing Information security regulatory documents, current harmonization techniques, information security implementation cost evaluation methods and ways to analyse Information security requirements by applying graph theory optimisation algorithms (Vertex cover and Graph isomorphism). The second chapter proposes ways to evaluate information security implementation and costs through a controls-based approach. The effectiveness of this method could be improved by implementing automated initial data gathering from Business processes diagrams. In the third chapter, adaptive mapping on the basis of Security ontology is introduced for harmonization of different security documents; such an approach also allows to apply visualization techniques for harmonization results presentation. Graph optimization algorithms (vertex cover algorithm and graph isomorphism algorithm) for Minimum Security Baseline identification and verification of achieved results against controls implemented in small and medium-sized enterprises were proposed. It was concluded that the proposed methods provide sufficient data for adjustment and verification of security controls applicable by multiple Information security documents.Dissertatio