Nikolaos Karalis

dblp:231/2929 · DBLP profile ↗
← Back
6ranked-venue papers in the field
3as first author
3since 2021 · last 2025
0000-0002-0710-7180ORCID · corroborated

Domains — venue-derived; a paper can count in several

Knowledge Engineering, Semantic Web & Information Systems · 4 (2 first)Data Mining & Knowledge Discovery · 1 (1 first)Big Data, Cloud & Distributed Data Systems · 1
YearPublicationVenuePosition
2025 Efficient Updates for Worst-Case Optimal Join Triple Stores
Alexander Bigerl, Nikolaos Karalis, Liss Heidrich, Axel-Cyrille Ngonga Ngomo
ISWC (1)2
2024 Efficient Evaluation of Conjunctive Regular Path Queries Using Multi-way Joins
Nikolaos Karalis, Alexander Bigerl, Liss Heidrich, Mohamed Ahmed Sherif, Axel-Cyrille Ngonga Ngomo
ESWC (1)1
2024 Evaluating Negation with Multi-way Joins Accelerates Class Expression Learning
Nikolaos Karalis, Alexander Bigerl, Caglar Demir, Liss Heidrich, Axel-Cyrille Ngonga Ngomo
ECML/PKDD (6)1
2019 Extending the YAGO2 Knowledge Graph with Precise Geospatial Knowledge
abstract
We extend YAGO2 with geospatial information represented by geometries (e.g., lines, polygons, multipolygons, etc.) encoded by Open Geospatial Consortium standards. The new geospatial information comes from official sources such as the administrative divisions of countries but also from volunteered open data of OpenStreetMap. The resulting knowledge graph is currently the richest in terms of geospatial information publicly available, open source, knowledge graph.
Nikolaos Karalis, Georgios M. Mandilaras, Manolis Koubarakis
ISWC (2)1
2018 Distributed Execution of Spatial SQL Queries
abstract
The volume of available spatial data that is generated and collected has significantly increased in the last few years. A number of applications based on Map-Reduce-like systems and cloud infrastructure have emerged. These applications offer a variety of features, however they differ in terms of spatial functions, partitioning and indexing. In this paper we present our own implementation that enables spatial support for distributed execution of spatial SQL queries as part of the system Exareme. Then, we evaluate some of the State-of-the-Art existing geospatial distributed systems, emphasizing on systems based on Apache Spark. We conduct detailed functional and performance benchmarks that include corner cases that stress the systems in comparison and reveal their advantages and weaknesses in both functionality and performance.
Konstantinos Giannousis, Konstantina Bereta, Nikolaos Karalis, Manolis Koubarakis
IEEE BigData3
2018 GeoTriples: Transforming geospatial data into RDF graphs using R2RML and RML mappings
Kostis Kyzirakos, Dimitrianos Savva, Ioannis Vlachopoulos, Alexandros Vasileiou 0003, Nikolaos Karalis, Manolis Koubarakis, Stefan Manegold
J. Web Semant.5