U
Ulf Leser
Researcher at Humboldt University of Berlin
Publications - 287
Citations - 8615
Ulf Leser is an academic researcher from Humboldt University of Berlin. The author has contributed to research in topics: Workflow & Computer science. The author has an hindex of 44, co-authored 266 publications receiving 7443 citations. Previous affiliations of Ulf Leser include Humboldt State University & University of Potsdam.
Papers
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Book ChapterDOI
Querying distributed RDF data sources with SPARQL
Bastian Quilitz,Ulf Leser +1 more
TL;DR: DARQ provides transparent query access to multiple SPARQL services, i.e., it gives the user the impression to query one single RDF graph despite the real data being distributed on the web, and uses query rewriting and cost-based query optimization to speed up query execution.
Journal ArticleDOI
The Stratosphere platform for big data analytics
Alexander Alexandrov,Rico Bergmann,Stephan Ewen,Johann-Christoph Freytag,Fabian Hueske,Arvid Heise,Odej Kao,Marcus Leich,Ulf Leser,Volker Markl,Felix Naumann,Mathias Peters,Astrid Rheinländer,Matthias J. Sax,Sebastian Schelter,Mareike Hoger,Kostas Tzoumas,Daniel Warneke +17 more
TL;DR: The overall system architecture design decisions are presented, Stratosphere is introduced through example queries, and the internal workings of the system’s components that relate to extensibility, programming model, optimization, and query execution are dive into.
Journal ArticleDOI
Deep learning with word embeddings improves biomedical named entity recognition.
TL;DR: This work shows that a completely generic method based on deep learning and statistical word embeddings [called long short‐term memory network‐conditional random field (LSTM‐CRF)] outperforms state‐of‐the‐art entity‐specific NER tools, and often by a large margin.
Journal ArticleDOI
ChemSpot: a hybrid system for chemical named entity recognition
TL;DR: ChemSpot, a named entity recognition (NER) tool for identifying mentions of chemicals in natural language texts, including trivial names, drugs, abbreviations, molecular formulas and International Union of Pure and Applied Chemistry entities is presented.
Proceedings ArticleDOI
Fast and practical indexing and querying of very large graphs
Silke Trißl,Ulf Leser +1 more
TL;DR: The GRIPP index structure (GRaph Indexing based on Pre- and Postorder numbering) for answering reachability queries in graphs is presented and can be integrated into existing graph-oriented applications.