Our work in the Semantic Web area currently concentrates on the following topics:
Large knowledge graphs with geospatial knowledge. Recently, large knowledge graphs have been used to move search engines to a new semantic level. However, these knowledge graphs contain little or no geospatial knowledge. We are trying to change this, by extending the well-known knowledge graph Yago2.
Geospatial question answering. Current search engines like Google and experimental Question Answering systems cannot answer user requests with a geospatial dimension (e.g., Find cities of Germany where two rivers meet.) In our current work in project WDAqua we are working on extending QA systems with this functionality.
Extensions of RDF and SPARQL for the representation of temporal and spatial data. In this context we have developed the data model stRDF, the query language stSPARQL and the system Strabon. More information can be found in our publications e.g., our ISWC 2012 paper.