Community detection and its variations is one of the typically employed approaches for analyzing graph data originating from various diverse fields. In this paper, we focus on a particular approach for community detec...
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Community detection and its variations is one of the typically employed approaches for analyzing graph data originating from various diverse fields. In this paper, we focus on a particular approach for community detection capitalizing on hyperbolic network embedding, which is aimed at analyzing large data graphs. In order to enable its scaling to arbitrary sized data sets and respective data graphs, we extend it by incorporating a graph database approach. This allows for handling a larger number of nodes and edges in the data graph. Also, we turn our focus on the discovery and visualization of communities in Resource Description Framework (RDF) data, namely over linked datasets from diverse areas, explaining how our approach can accommodate relevant analysis. We demonstrate the applicability of the new approach over both real-world and artificially generated datasets showing its feasibility in producing correct results, while being able to scale seamlessly in large datasets. The approach can be used for multi-lateral analysis of feature-rich graph data, originating from diverse sources, enabling the discovery of hidden correlations through the hyperbolic network embedding.
Most query languages for graph databases rely on exploring the topological properties of the data by using paths. However, many applications require more complex patterns to be matched against the graph to obtain desi...
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Most query languages for graph databases rely on exploring the topological properties of the data by using paths. However, many applications require more complex patterns to be matched against the graph to obtain desired results. For this reason a version of the standard XML query language XPath has been adapted to work over graphs. In this paper we study static analysis aspects of this language, concentrating on problems such as containment, equivalence and satisfiability. We show that for the full language all of the problems are undecidable. By restricting the language we then obtain several natural fragments whose complexity ranges from PSPACE-complete to EXPTIME-complete. (C) 2016 Elsevier B.V. All rights reserved.
XACML policies can be presented in a graph data structure, but while these solutions increase performance, they also drastically decrease functionality. To address this, the authors' approach models and stores XAC...
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XACML policies can be presented in a graph data structure, but while these solutions increase performance, they also drastically decrease functionality. To address this, the authors' approach models and stores XACML policies in a graph database.
Query languages for graph databases started to be investigated some 25 years ago. With much current data, such as linked data on the Web and social network data, being graph-structured, there has been a recent resurge...
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Query languages for graph databases started to be investigated some 25 years ago. With much current data, such as linked data on the Web and social network data, being graph-structured, there has been a recent resurgence in interest in graph query languages. We provide a brief survey of many of the graph query languages that have been proposed, focussing on the core functionality provided in these languages. We also consider issues such as expressive power and the computational complexity of query evaluation.
In this paper, we propose a compact data structure to store labeled attributed graphs based on the k(2)-tree, which is a very compact data structure designed to represent a simple directed graph. The idea we propose c...
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In this paper, we propose a compact data structure to store labeled attributed graphs based on the k(2)-tree, which is a very compact data structure designed to represent a simple directed graph. The idea we propose can be seen as an extension of the k(2)-tree to support property graphs. In addition to the static approach, we also propose a dynamic version of the storage representation, which allows flexible schemas and insertion or deletion of data. We provide an implementation of a basic set of operations, which can be combined to form complex queries over these graphs with attributes. We evaluate the performance of our proposal with existing graph database systems and prove that our compact attributed graph representation obtains also competitive time results.
In the era of big data, data analytics, business intelligence database management plays a vital role from technical business management and research point of view. Over many decades, database management has been a top...
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The present paper reports on the advantages of using graph databases in the development of dynamic language models in Spoken Language Understanding applications, such as spoken dialogue systems. First of all, we intro...
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Numerous irregular graph datasets, for example social networks or web graphs, may contain even trillions of edges. Often, their structure changes over time and they have domain-specific rich data associated with verti...
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Numerous irregular graph datasets, for example social networks or web graphs, may contain even trillions of edges. Often, their structure changes over time and they have domain-specific rich data associated with vertices and edges. graph database systems such as Neo4j enable storing, processing, and analyzing such large, evolving, and rich datasets. Due to the sheer size and irregularity of such datasets, these systems face unique design challenges. To facilitate the understanding of this emerging domain, we present the first survey and taxonomy of graph database systems. We focus on identifying and analyzing fundamental categories of these systems (e.g., document stores, tuple stores, native graph database systems, or object-oriented systems), the associated graph models (e.g., Resource Description Framework or Labeled Property graph), data organization techniques (e.g., storing graph data in indexing structures or dividing data into records), and different aspects of data distribution and query execution (e.g., support for sharding and Atomicity, Consistency, Isolation, Durability). Fifty-one graph database systems are presented and compared, including Neo4j, OrientDB, and Virtuoso. We outline graph database queries and relationships with associated domains (NoSQL stores, graph streaming, and dynamic graph algorithms). Finally, we outline future research and engineering challenges related to graph databases.
Process event data is usually stored either in a sequential process event log or in a relational database. While the sequential, single-dimensional nature of event logs aids querying for (sub)sequences of events based...
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Process event data is usually stored either in a sequential process event log or in a relational database. While the sequential, single-dimensional nature of event logs aids querying for (sub)sequences of events based on temporal relations such as "directly/eventually-follows," it does not support querying multi-dimensional event data of multiple related entities. Relational databases allow storing multi-dimensional event data, but existing query languages do not support querying for sequences or paths of events in terms of temporal relations. In this paper, we propose a general data model for multi-dimensional event data based on labeled property graphs that allows storing structural and temporal relations in a single, integrated graph-based data structure in a systematic way. We provide semantics for all concepts of our data model, and generic queries for modeling event data over multiple entities that interact synchronously and asynchronously. The queries allow for efficiently converting large real-life event data sets into our data model, and we provide 5 converted data sets for further research. We show that typical and advanced queries for retrieving and aggregating such multi-dimensional event data can be formulated and executed efficiently in the existing query language Cypher, giving rise to several new research questions. Specifically, aggregation queries on our data model enable process mining over multiple inter-related entities using off-the-shelf technology.
graph databases are a powerful data structure that can be applied to solve a variety of problems. They are widely used in electronic communications network due to the need for effective management of complex network s...
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