Erweiterte Suche der Leibniz Universität Hannover

Generating SPARQL queries using templates verfasst von Saeedeh Shekarpour, Sören Auer, Axel Cyrille Ngonga Ngomo, Daniel Gerber, Sebastian Hellmann, Claus Stadler Externe Organisation en Universität Leipzig Typ Artikel Journal Web Intelligence and Agent Systems Band 11 Seiten 283 295 Anzahl der Seiten 13 ISSN 1570 1263 Publikationsdatum 2013 Publikationsstatus Veröffentlicht Peer reviewed Ja ASJC Scopus Sachgebiete Software, Computernetzwerke und kommunikation, Artificial intelligence Elektronische Version en https://doi.org/10.3233/WIA 130275 Zugang: Geschlossen BibTeX article 131ddb556dca4ce9be62d2f98db85f0d, title Generating SPARQL queries using templates , keywords Graph pattern, Keyword search, SPARQL query , author Saeedeh Shekarpour and S o ren Auer and Ngonga Ngomo , Axel Cyrille and Daniel Gerber and Sebastian Hellma...

Evaluating Recursive Queries in Distributed Databases verfasst von Wolfgang Nejdl, Stefano Ceri, Gio Wiederhold Abstract In this paper, we study the execution of logic queries in a distributed database environment. We assume that each local database system can execute logic queries, and we design methods for the efficient execution of queries requiring data from multiple sites. Conventional optimization strategies which are well known in the field of distributed databases, such as the early evaluation of selection conditions and the clustering of processing to manipulate and exchange large sets of tuples, are redefined in view of the additional difficulties due to logic queries, in particular to recursive rules.

Furthermore, in order to detect the sentiment expressed in queries, we build different classifiers based on query texts, query result titles, and snippets. We demonstrate the virtue of query sentiment detection in two different use cases. First, we define a query recommendation scenario that employs sentiment detection of results to recommend additional queries for polarized queries issued by search engine users. The second application scenario is controversial topic discovery, where query sentiment classifiers are employed to discover previously unknown topics that trigger both highly positive and negative opinions among the users of a search engine.

Learning to Detect Event Related Queries for Web Search verfasst von Nattiya Kanhabua, Tu Ngoc Nguyen, Wolfgang Nejdl Abstract In many cases, a user turns to search engines to find information about real world situations, namely, political elections, sport competitions, or natural disasters. Such temporal querying behavior can be observed through a significant number of event related queries generated in web search. In this paper, we study the task of detecting event related queries, which is the first step for understanding temporal query intent and enabling different temporal search applications, e.g., time aware query auto completion, temporal ranking, and result diversi cation.

We prove a trichotomy theorem for the generalized conjunctive query counting problem, showing this way that, contrary to the corresponding decision problems, constraint satisfaction and conjunctive query containment differ for other computational goals. We also study the audit problem for conjunctive queries asking whether there exists a frozen variable in a given query. This problem is important in databases supporting statistical queries.

Processing and optimization of complex queries in schema based P2P networks authored by Hadhami Dhraief, Alfons Kemper, Wolfgang Nejdl, Christian Wiesner Abstract Peer to Peer infrastructures are emerging as one of the important data management infrastructures in the World Wide Web. So far, however, most work has focused on simple P2P networks which tackle efficient query distribution to a large set of peers but assume that each query can be answered completely at each peer. For queries which need data from more than one peer to be executed this is clearly insufficient. Unfortunately, though quite a few database techniques can be re used in the P2P context, P2P data management infrastructures pose additional challenges caused by the dynamic nature of these networks.

Distributed queries and query optimization in schema based P2P systems verfasst von Ingo Brunkhorst, Hadhami Dhraief, Alfons Kemper, Wolfgang Nejdl, Christian Wiesner Abstract Databases have employed a schema based approach to store and retrieve structured data for decades. For peer to peer P2P networks, similar approaches are just beginning to emerge, also motivated by the fact, that sending atomic queries to the appropriate peers clearly fails for queries which need data from more than one peer to be executed. While quite a few database techniques can be re used in this new context, a P2P data management infrastructure poses additional challenges which have to be solved before schema based P2P networks become as common as schema based databases.

Processing and optimization of complex queries in schema based P2P networks verfasst von Hadhami Dhraief, Alfons Kemper, Wolfgang Nejdl, Christian Wiesner Abstract Peer to Peer infrastructures are emerging as one of the important data management infrastructures in the World Wide Web. So far, however, most work has focused on simple P2P networks which tackle efficient query distribution to a large set of peers but assume that each query can be answered completely at each peer. For queries which need data from more than one peer to be executed this is clearly insufficient. Unfortunately, though quite a few database techniques can be re used in the P2P context, P2P data management infrastructures pose additional challenges caused by the dynamic nature of these networks.

SMJoin A multi way join operator for SPARQL queries verfasst von Mikhail Galkin, Kemele M. Endris, Maribel Acosta, Diego Collarana, Maria Esther Vidal, Sören Auer Organisationseinheit en Fachgebiet Data Science and Digital Libraries Externe Organisation en Rheinische Friedrich Wilhelms Universität Bonn Karlsruher Institut für Technologie KIT Fraunhofer Institut für Intelligente Analyse und Informationssysteme IAIS Technische Informationsbibliothek TIB Leibniz Informationszentrum Technik und Naturwissenschaften und Universitätsbibliothek Typ Aufsatz in Konferenzband Seiten 104 111 Anzahl der Seiten 8 Publikationsdatum 11.09.2017 Publikationsstatus Veröffentlicht Peer reviewed Ja ASJC Scopus Sachgebiete Software, Mensch Maschine Interaktion, Maschinelles Sehen und Mustererkennung, Computernetzwerke und kommunikation Elektronisc...

Processing and optimization of complex queries in schema based P2P networks verfasst von Hadhami Dhraief, Alfons Kemper, Wolfgang Nejdl, Christian Wiesner Abstract Peer to Peer infrastructures are emerging as one of the important data management infrastructures in the World Wide Web. So far, however, most work has focused on simple P2P networks which tackle efficient query distribution to a large set of peers but assume that each query can be answered completely at each peer. For queries which need data from more than one peer to be executed this is clearly insufficient. Unfortunately, though quite a few database techniques can be re used in the P2P context, P2P data management infrastructures pose additional challenges caused by the dynamic nature of these networks.

Asking about possibilities revision and update semantics for subjunctive queries Extended report verfasst von Wolfgang Nejdl, Markus Banagl Abstract The AGM rationality postulates for belief revision play an important role in the formalization of subjunctive queries over knowledge bases.

SUITS Faceted user interface for constructing structured queries from keywords verfasst von Elena Demidova, Xuan Zhou, Gideon Zenz, Wolfgang Nejdl Abstract Keyword search and database query are two ways for retrieving data in real world settings. In this demonstration, we show SUITS, a novel search interface over relational databases that smoothly integrates the flexibility of keyword search and the precision of database queries. SUITS allows users to start with arbitrary keyword queries, refine them incrementally by following the suggestions given by the system and finally obtain desired structured queries.

We prove a trichotomy theorem for the generalized conjunctive query counting problem, showing this way that, contrary to the corresponding decision problems, constraint satisfaction and conjunctive query containment differ for other computational goals. We also study the audit problem for conjunctive queries asking whether there exists a frozen variable in a given query. This problem is important in databases supporting statistical queries.

SINA Semantic interpretation of user queries for question answering on interlinked data verfasst von Saeedeh Shekarpour, Edgard Marx, Axel Cyrille Ngonga Ngomo, Sören Auer Externe Organisation en Universität Leipzig Rheinische Friedrich Wilhelms Universität Bonn Fraunhofer Institut für Intelligente Analyse und Informationssysteme IAIS Typ Artikel Journal Journal of Web Semantics Band 30 Seiten 39 51 Anzahl der Seiten 13 ISSN 1570 8268 Publikationsdatum 26.06.2014 Publikationsstatus Veröffentlicht Peer reviewed Ja ASJC Scopus Sachgebiete Software, Mensch Maschine Interaktion, Computernetzwerke und kommunikation Elektronische Version en https://doi.org/10.1016/j.websem.2014.06.002 Zugang: Geschlossen BibTeX article 1c314c442abc48359b7ee07c9e102d4c, title SINA: Semantic interpretation of user queries for question answering on in...

DBpedia SPARQL Benchmark Performance Assessment with Real Queries on Real Data verfasst von Mohamed Morsey, Jens Lehmann, Sören Auer, Axel Cyrille Ngonga Ngomo Externe Organisation en Universität Leipzig Typ Aufsatz in Konferenzband Seiten 454 469 Anzahl der Seiten 16 Publikationsdatum 2011 Publikationsstatus Veröffentlicht Peer reviewed Ja ASJC Scopus Sachgebiete Theoretische Informatik, Informatik insg. Elektronische Version en https://doi.org/10.1007/978 3 642 25073 6 29 Zugang: Geschlossen BibTeX inproceedings 8cedd81fd9c648e69e60585bf49a225f, title DBpedia SPARQL Benchmark: Performance Assessment with Real Queries on Real Data , author Mohamed Morsey and Jens Lehmann and S o ren Auer and Ngonga Ngomo , Axel Cyrille , note Funding information: This work was supported by a grant from the European Union textquoteright s 7th...