Web and Social Data Analysis

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Semantic Web data

Description

Despite the large volume of work on querying large RDF knowledge bases, only a few studies efficiently address spatial semantics in RDF data; existing initiatives mainly focus on supporting GeoSPARQL features with external spatial indices like the R-tree, and less on performance optimization. Our work proposed a number of techniques that can be applied to RDF engines in order to efficiently support spatial queries such as range selections and spatial joins. As a proof of concept, the proposed techniques were implemented inside the RDF-3X open-source store. Our key contribution of is an effective encoding scheme that encodes spatial approximations inside the identifiers of RDF entities with spatial locations and geometries. This scheme allows us to apply online cheap filters and spatial join algorithms without accessing the exact geometries of the involved entities.

Publications

Theses

 

Geo-social data

Description

The growth of Location-aware Social Networks (LASN) is unprecedented; given that users in LASNs such as Foursquare can rate venues, make recommendations and advertise interesting events, the economic importance and the potential impact of LASNs for businesses become apparent. Motivated by word-of-mouth and viral marketing campaigns, our work introduced the task of identifying the top-k Regionally Influential LASN Users (k-RIL). For example, an organizer of a city-wide festival is recruiting the most influential users within each district to locally advertise the festival. To solve k-RIL, we first proposed a novel propagation model and designed a methodology for computing the influence power of a user based on closeness centrality at the social graph. Then, we devised evaluation algorithms that examine candidate users in the order of their expected influence.

Publication

  • Panagiotis Bouros, Theodoros Chondrogiannis and Daniel Kowalski:
    Fast Geosocial Reachability Queries
    Proceedings of the 28th International Conference on Extending Database Technology (EDBT), Barcelona, Spain, March 25-28, 2025

  • Abed Al Rahman Sansour, Panagiotis Bouros and Theodoros Chondrogiannis:
    Towards Generating Realistic Geosocial Networks
    Proceedings of the 7th ACM SIGSPATIAL International Workshop on Location-Based Recommendations, Geosocial Networks, and Geoadvertising (LocalRec), Hamburg, Germany, November 13, 2023

  • Panagiotis Bouros, Dimitris Sacharidis and Nikos Bikakis:
    Regionally Influential Users in Location-Aware Social Networks
    Proceeding of the 22nd ACM International Conference on Advances in Geographic Information Systems (ACM SIGSPATIAL), Dallas, Texas, USA, November 4-7, 2014

Theses

  • Tobias Laures
    Academic Social Neworks-Spatial Evolution of Scientific Communities
    Master thesis, Johannes Gutenberg University Mainz, Germany

  • Julius Hoffmann
    A Graphical Interface for Managing Geosocial networks
    Bachelor thesis, Johannes Gutenberg University Mainz, Germany, 2024

  • Abed Al Rahman Sansour
    A Graphical User Interface for generating Geosocial networks
    Bachelor thesis, Johannes Gutenberg University Mainz, Germany, 2023

  • Daniel-Valentin Kowalski:
    Evaluating GeoSocial Reachability Queries

    • Bachelor thesis, Johannes Gutenberg University Mainz, Germany, 2021

  • Mohamed Masarwa:
    Monitoring Geo-Social Influence in Location-Aware Social Networks
    Bachelor thesis, Johannes Gutenberg University Mainz, Germany, 2019

Source code

 

Web directories

Description

Hierarchical structures such as topic directories are a popular way to organize information on the Web. In this context, we investigated the role of paths as knowledge artifacts; in particular, we proposed models to represent topic directories and a query language to manipulate path-like patterns together with raw data. Further, we studied the personlization of Web directories by mining user navigation patterns. For this purpose, we presented techniques for discovering group of users who exhibit similar navigation behaviour, termed interest groups. Essentially, the proposed personalization tasks aim at creating links termed shortcuts, between categories in the directory.

Publications

Theses