Access to Objects by Path Expressions and Rules (2009)
Jurgen Frohn, Georg Lausen, Heinz Upho
Object oriented databases provide rich structuring capabilities to organize the objects
Architecture of Web Access with FLORID (2009)
Wolfgang May, Rainer Himmeröder, Georg Lausen, Bertram Ludäscher, Integrated System
Implementation: F-Logic/FLORID
Design and Applicability of a Transparent Network Redirection Layer (2009)
Pedro Jose Marron, Georg Lausen
Abstract. In this paper we present the design, applicability and preliminary experimental results of the network redirection layer developed at the University of Freiburg as part of Plexor, a...
To appear in Springer LNCS. On a Declarative Semantics for Web Queries (2009)
Rainer Himmeroder, Georg Lausen, Bertram Ludascher
Abstract. With the increasing importance of the World Wide Web as an information source, there is a growing interest for integration of Web and database technology. Several Web query languages have...
This paper considers the problem of containment of conjunctive queries (CQ) with disjunctive integrity constraints. Query containment problem in the presence of integrity constraints has been studied...
On Chase Termination Beyond Stratification (2009)
Meier, Michael, Schmidt, Michael, Lausen, Georg
We study the termination problem of the chase algorithm, a central tool in various database problems such as the constraint implication problem, Conjunctive Query optimization, rewriting queries...
Meier, Michael, Schmidt, Michael, Lausen, Georg
The chase procedure, an algorithm proposed 25+ years ago to fix constraint violations in database instances, has been successfully applied in a variety of contexts, such as query optimization, data...
Foundations of SPARQL Query Optimization (2008)
Schmidt, Michael, Meier, Michael, Lausen, Georg
The SPARQL query language is a recent W3C standard for processing RDF data, a format that has been developed to encode information in a machine-readable way. We investigate the foundations of SPARQL...
SP2Bench: A SPARQL Performance Benchmark (2008)
Schmidt, Michael, Hornung, Thomas, Lausen, Georg, Pinkel, Christoph
Recently, the SPARQL query language for RDF has reached the W3C recommendation status. In response to this emerging standard, the database community is currently exploring efficient storage...
Learning Rules to Pre-process Web Data for Automatic Integration (2008)
Kai Simon, Thomas Hornung, Georg Lausen
Web pages such as product catalogues and web sites resulting from querying a search engine often follow a global layout template which facilitates the retrieval of information for a user. In this...
GI-Arbeitskreis WEB und DATENBANKEN 504 (2008)
Genehmigter Auszug Aus, R. Eckstein, Donald Kossmann, Jernej Kovse, Theo Härder, Marcel Karnstedt, ...
Querying transformed XML documents: Determining a sufficient fragment of the original document 198
Abstract Pre-Analysis Locking: A Safe and Deadlock Free Locking Policy (2008)
Georg Lausen, Eljas Soisalon-soininen, Peter Widmayer
A safe and deadlock free lock policy is introduced, called pre-analysis locking. Pre-analysis locking is based on an efficient geometric algorithm which inserts lock and unlock operations into the...
Cai-nicolas Ziegler, Kai Simon, Georg Lausen
Taxonomic measures of semantic proximity allow us to compute the relatedness of two concepts. These metrics are versatile instruments required for diverse applications, e.g., the Semantic Web,...
Learning Rules to Pre-process Web Data for Automatic Integration (2008)
Kai Simon, Thomas Hornung, Georg Lausen
Web pages such as product catalogues and web sites resulting from querying a search engine often follow a global layout template which facilitates the retrieval of information for a user. In this...
Dekan Prof, Dr. Jan Korvink, Referenten Prof, Dr. Georg Lausen, Prof Dr, ...
geboren am 28.11.1977 in Würzburg
Paradigms for Decentralized Social Filtering Exploiting Trust Network Structure (2008)
Cai-nicolas Ziegler, Georg Lausen
Abstract. Recommender systems, notably collaborative and hybrid information filtering approaches, vitally depend on neighborhood formation, i.e., selecting small subsets of most relevant peers from...
Cai-nicolas Ziegler, Lars Schmidt-thieme, Georg Lausen
Content-driven and hybrid recommender systems propose products to customers making use of descriptive features and behavioral patterns, likewise. While most approaches exploit classical information...
TRANSFORM: A TRANSACTION SAFE WEB APPLICATION MODEL (2008)
i.e., all data processing and business logic resides on the server while the client’s role is to arrange and display the user interface. When transactions come into play, which may naturally span...
Cai-nicolas Ziegler, Georg Lausen, Lars Schmidt-thieme
Recommender systems have been subject to an enormous rise in popularity and research interest over the last ten years. At the same time, very large taxonomies for product classification are becoming...
ABSTRACT From HTML Documents to Web Tables and Rules (2008)
{ksimon,lausen} AT informatik.uni-freiburg.de We present a browser-extending Semantic Web extraction system that maps HTML documents to tables and, where possible, to rules. First, the basic data...
Thorsten Kramer, Dozent Prof, Dr. Georg Lausen, Betreuer Dipl. -inf, Thomas Hornung
Verwendung der aufgeführten Hilfsmittel erstellt wurde. Alle Stellen, die ich wörtlich
Iztok Savnik, Georg Lausen, Hans-peter Kahle, Heinrich Spiecker
Time series are time-stamped sequences of values which represent a parameter of the observed processes in subsequent time points. Given a set of time series describing a set of similar processes, the...
Design and Applicability of a Transparent Network Redirection Layer (2007)
Abstract. In this paper we present the design, applicability and preliminary experimental results of the network redirection layer developed at the University of Freiburg as part of Plexor, a...
FLORID-- Ein Prototyp f ur F-Logik Report 84 (2007)
J Frohn, Rainer Himmer, Paul-th. Kandzia, Georg Lausen
Zusammenfassung F-Logik [17] ist eine m achtige Sprache, die deduktive
Updates by Reasoning about States (2007)
About States, Georg Lausen, Georg Lausen, Bertram Ludascher, Bertram Ludascher
We present a language extension to Datalog which allows to specify deterministic update procedures in a declarative way. Existing update languages either rely on procedural aspects of program...
A Formal Analysis of the Lightweight Directory Access Protocol (2007)
Abstract. LDAP (Lightweight Directory Access Protocol) directories are being widely used on the Web, for white pages information, user profiles, etc. The advantages LDAP offers are (i) the support...
s). We propose a new method for the containment test of CQ (2007)
We consider the problem of query containment for conjunctive queries with safe negated subgoals
Serge Abiteboul, Georg Lausen, Heinz Uphoff, Emmanuel Waller
We show how classical datalog semantics can be used directly and very simply to provide semantics to a syntactic extension of datalog with methods, classes, inheritance, overloading and late binding....
Abstract. The goal of information extraction from the Web is to provide an integrated view on heterogeneous information sources via a common data model and query language. A main problem with current...
Wolfgang May, Rainer Himmer, Georg Lausen, Bertram Lud
ffl Use of generic rules for standard tasks ffl Implementation: F-Logic/FLORID ffl Examples / Case Studies:
Aspects of Rewriting Queries on Semistructured Data (2007)
Rewriting queries using materialized views has been widely studied in recent years, although most of the work has been done based on relational models. We are interested in determining what aspects...
Michael Kifer, Georg Lausen, James Wu
z We propose a novel formalism, called Frame Logic (abbr., F-logic), that accounts in a clean and declarative fashion for most of the structural aspects of object-oriented and frame-based languages....
Bertram Lud Ascher, Rainer Himmer Oder, Georg Lausen, Wolfgang May
Abstract--- The closely related research areas management of semistructured data and languages for querying the Web have recently attracted a lot of interest. We argue that languages supporting...
Rainer Himmeroder, Georg Lausen, Bertram Ludascher
Abstract. The goal of information extraction from the Web is to provide an integrated view on heterogeneous information sources via a common data model and query language. A main problem with current...
Semantic Peer-to-Peer Recommender Systems (2005)
For the Semantic Web vision to come true, the power of distributed applications needs to be leveraged. But the World Wide Web and its services, as we know them today, are still largely based on...
Updates by Reasoning about States (2004)
Lausen, Georg, Ludaescher, Bertram
It has been argued that some sort of control must be introduced in order to perform update operations in deductive databases. Indeed, many approaches rely on a procedural semantics of rule based...
Access to Objects by Path Expressions and Rules (2004)
Frohn, Jürgen, Lausen, Georg, Uphoff, Heinz
Object oriented databases provide rich structuring capabilities to organize the objects being relevant for a given application. Due to the possible complexity of object structures, path expressions...
Updates in a Rule based Language for Objects (2004)
Lausen, Georg, Kramer, Michael, Saake, Gunter
The integration of object-oriented concepts into deductive databases has been investigated for a certain time now. Various approaches to incorporate updates into deduction have been proposed. The...
Evaluation Aspects of a Object-Oriented Deductive Database Language (2004)
Recently, F-logic has been proposed as an attempt to extend deductive databases by typical concepts of object-oriented languages. Among these concepts are complex objects, (term-based) object...
Logical Foundations of Object-Oriented and Frame-Based Languages (2004)
Kifer, Michael, Lausen, Georg, Wu, James
We propose a novel logic, called Frame Logic (abbr., F-logic), that accounts in a clean, declarative fashion for most of the structural aspects of object-oriented and frame-based languages. These...
Analyzing Correlation between Trust and User Similarity in Online Communities (2004)
Cai-nicolas Ziegler, Georg Lausen
Abstract. Past evidence has shown that generic approaches to recommender systems based upon collaborative filtering tend to poorly scale. Moreover, their fitness for scenarios supposing distributed...
Spreading Activation Models for Trust Propagation (2004)
Cai-Nicolas Ziegler, Georg Lausen
Semantic Web endeavors have mainly focused on issues pertaining to knowledge representation and ontology design. However, besides understanding information metadata stated by subjects, knowing about...
Analyzing Correlation between Trust and User Similarity in Online Communities (2004)
Cai-nicolas Ziegler, Georg Lausen
Abstract. Past evidence has shown that generic approaches to recommender systems based upon collaborative filtering tend to poorly scale. Moreover, their fitness for scenarios supposing distributed...
Catalog integration made easy (2003)
Pedro José Marrón, Georg Lausen, Martin Weber
Abstract: In this paper, we study adaptive evaluation techniques for querying XMLbased electronic catalogs, and show, by means of experiments performed on real-world catalogs, that our approach can...
Adaptive Evaluation Techniques for Querying XML-based E-Catalogs (2002)
Georg Lausen, Pedro Jose Marron
The integration of electronic catalogs (eCatalogs) is one of the most important aspects for the successful deployment of electronic commerce systems, since they are usually the only communication...
Ontology-based querying of linked XML documents (2002)
We investigate the Lightweight Directory Access Protocol (LDAP) that provides a powerful means to link distributed data collections into an entity searchable as a single collection. Besides the...
Conjunctive query containment in the presence of disjunctive integrity constraints (2002)
This paper considers the problem of containment of conjunctive queries (CQ) with disjunctive integrity constraints. Query containment problem in the presence of integrity constraints has been studied...
Ontology-Based Querying of Linked XML Documents (2002)
A<*<*"BC!D#!6<*5 E(3F:?AB9GH#!D#JI!D/0 GH#!D#JI 1 4 *9#!N $O 040 ! +#! +#! 9#!N $O 040 #879* ,56#":; ' 195 !<=+K ,5R<*5*<& #! 4%TSM U ,5R<*5*<&...
Efficient Cache Answerability for XPath Queries (2002)
Pedro José Marrón, Georg Lausen
The problem of cache answerability has traditionally been studied over conjunctive queries performed on top of a relational database system. However, with the proliferation of semistructured data...
Adaptive Evaluation Techniques for Querying XML-based E-Catalogs (2002)
Georg Lausen, Pedro Josémarrón
The integration of electronic catalogs (eCatalogs) is one of the most important aspects for the successful deployment of electronic commerce systems, since they are usually the only communication...
Efficient Cache Answerability for XPath Queries (2002)
Pedro José Marrón, Georg Lausen
Abstract. The problem of cache answerability has traditionally been studied over conjunctive queries performed on top of a relational database system. However, with the proliferation of...
LDAPbased ontology for information integration (2001)
Abstract. The increase in popularity of the Internet has lead to the proliferation of heterogeneous information systems that could be better utilized if they operated under a common query interface....
HLCaches: An LDAP-based distributed cache technology for XML (2001)
The proliferation of XML and its settlement as the de facto standard for information interchange in Internet, as well as the development of querying languages for XML, like XPath, have lead to a...
HLCaches: An LDAP-based distributed cache technology for XML (2001)
The proliferation of XML and its settlement as the de facto standard for information interchange in Internet, as well as the development of querying languages for XML, like XPath, have lead to a...
Ontology-based access to heterogeneous XML data (2001)
Lule Ahmedi, Pedro Jose Marron, Georg Lausen
Abstract: With the increase in popularity of XML on the Internet, the requirements of database management systems have shifted from traditional transaction-based databases towards the kind of...
Transaction Synchronization for XML Data in Client-Server Web Applications (2001)
Wolfgang Benn, Erhard Rahm (hrsg, Eingeladener Vortrag, Lule Ahmedi, Pedro José Marrón, Georg Lausen, ...
GI/OCG-Jahrestagung 2001 in Wien behandelt die Nutzung und Weiterentwicklung von Datenbanktechnologien im World Wide Web, welches zahlreiche spannende Herausforderungen an die Datenverwaltung stellt....
LDAPbased ontology for information integration (2001)
Lule Ahmedi, Pedro Jose Marron, Georg Lausen
Abstract. The increase in popularity of the Internet has lead to the proliferation of heterogeneous information systems that could be better utilized if they operated under a common query interface....
On processing XML in LDAP (2001)
Pedro Jose Marron, Georg Lausen
The proliferation of XML and its settlement as the de facto standard for information interchange in Internet, as well as the development of query languages like XPath, have lead to a paradigm...
HLCaches: An LDAP-based distributed cache technology for XML (2001)
Pedro Jose Marron, Georg Lausen
The proliferation of XML and its settlement as the de facto standard for information interchange in Internet, as well as the development of querying languages for XML, like XPath, have lead to a...
Information Extraction from the Web (2000)
The goal of information extraction from the Web is to provide an integrated view on data from autonomous, heterogeneous information sources. The main problem with current wrapper /mediator approaches...
Algorithm for Matching Sets of Time Series (2000)
Iztok Savnik, Georg Lausen, Hans-peter Kahle, Heinrich Spiecker, Sebastian Hein
Time series are time-stamped sequences of values which represent a parameter of the observed processes in subsequent time points. Given a set of time series describing a set of similar processes, the...
MSTS: A System for Mining Sets of Time Series (2000)
Georg Lausen, Iztok Savnik, Aldar Dougarjapov
A system to support the mining task of sets of time series is presented. Amodel of a set of time series is constructed by a series of classi ers each de ning certain consecutive time points based on...
Information Extraction from the Web (2000)
The goal of information extraction from the Web is to provide an integrated view on data from autonomous, heterogeneous information sources. The main problem with current wrapper/mediator approaches...
On Active Deductive Databases: The Statelog Approach (1998)
Georg Lausen, Bertram Ludascher, Wolfgang May
Abstract. After briefly reviewing the basic notions and terminology of active rules and relating them to production rules and deductive rules, respectively, we survey a number of formal approaches to...
FLORID: A DOOD-System for Querying the Web (1998)
Rainer Himmeröder, Georg Lausen, Bertram Ludäscher, Christian Schlepphorst
Introduction. The limitations of locating and extracting useful information from the Web using current techniques are well-known: By browsing, only navigational access is possible, which is quite...
Search, Analysis, and Integration of Web Documents: A Case Study with FLORID (1998)
Rainer Himmeröder, Paul-th. Kandzia, Bertram Ludäscher, Wolfgang May, Georg Lausen
Languages supporting deduction and object-orientation seem particularly promising for querying and reasoning about structure and contents of the Web, and for the integration of information from...
On Active Deductive Databases: The Statelog Approach (1998)
Georg Lausen, Bertram Ludascher, Wolfgang May
Abstract. After brie y reviewing the basic notions and terminology of active rules and relating them to production rules and deductive rules, respectively, we survey a number of formal approaches to...
Managing semistructured data with FLORID: A deductive object-oriented perspective (1998)
Bertram Ludascher, Rainer Himmeroder, Georg Lausen, Wolfgang May
Abstract | The closely related research areas management of semistructured data and languages for querying the Web have recently attracted a lot of interest. We argue that languages supporting...
analysis, and integration of web documents: a case study with FLORID (1998)
Rainer Himmeroder, Paul-th. Kandzia, Bertram Ludascher, Wolfgang May, Georg Lausen
Languages supporting deduction and object-orientation seem particularly promising for querying and reasoning about structure and contents of the Web, and for the integration of information from...
On Active Deductive Databases: The Statelog Approach (1998)
Georg Lausen, Bertram Ludascher, Wolfgang May
Abstract. After brie y reviewing the basic notions and terminology of active rules and relating them to production rules and deductive rules, respectively, we survey a number of formal approaches to...
Referential actions as logical rules (1997)
Bertram Ludascher, Georg Lausen
Referential actions are specialized triggers used to automatically maintain referential integrity. While their local behavior can be grasped easily, it is far from clear what the combined effect of a...
Integrating Dynamic Aspects into Deductive Object-Oriented Databases (1997)
Abstract. We show how the dynamics of database systems can be modeled by making states first-class citizens in an object-oriented deductive database language. With states at the same time acting as...
On a declarative semantics for web queries (1997)
Rainer Himmeroder, Georg Lausen, Bertram Ludascher
Abstract. With the increasing importance of the World Wide Web as an information source, there is a growing interest for integration of Web and database technology. Several Web query languages have...
Well-Founded Semantics for Deductive Object-Oriented Database Languages (1997)
Bertram Ludascher, Georg Lausen
Abstract. We present a well-founded semantics for deductive objectoriented database (dood) languages by applying the alternating-fixpoint characterization of the well-founded model to them. In order...
On a declarative semantics for web queries (1997)
Rainer Himmeroder, Georg Lausen, Bertram Ludascher
Abstract. With the increasing importance of the World Wide Web as an information source, there is a growing interest for integration of Web and database technology. Several Web query languages have...
Referential actions as logical rules (1997)
Bertram Ludascher, Georg Lausen
Referential actions are specialized triggers used to automatically maintain referential integrity. While their local behavior can be grasped easily, it is far from clear what the combined effect of a...
FLORID - A Prototype for F-Logic (1997)
Jürgen Frohn, Rainer Himmeröder, Paul-th. Kandzia, Georg Lausen, Christian Schlepphorst
this paper we present FLORID
FLORID - Ein Prototyp für F-Logik (1997)
Jürgen Frohn, Rainer Himmeröder, Paul-th. Kandzia, Georg Lausen, Christian Schlepphorst
er verbindet: -- Der deduktive Ansatz versucht, die L ucke zwischen Datenbanken und Anwendungen (impedance mismatch) zu schließen oder zumindest zu verkleinern, indem die M achtigkeit der...
On a declarative semantics for web queries (1997)
Rainer Himmeroder, Georg Lausen, Bertram Ludascher
Abstract. With the increasing importance of the World Wide Web as an information source, there is a growing interest for integration of Web and database technology. Several Web query languages have...
Well-Founded Semantics for Deductive Object-Oriented Database Languages (1997)
Wolfgang May, Bertram Ludascher, Georg Lausen
Abstract. We present awell-founded semantics for deductive objectoriented database (dood) languages by applying the alternating- xpoint characterization of the well-founded model to them. In order to...
Integrating Dynamic Aspects into Deductive Object-Oriented Databases (1997)
Abstract. We showhowthe dynamics of database systems can be modeled by making states rst-class citizens in an object-oriented deductive database language. With states at the same time acting as...
Referential actions as logical rules (1997)
Bertram Ludascher, Wolfgang May, Georg Lausen
Referential actions are specialized triggers used to automatically maintain referential integrity. While their local behavior can be grasped easily, it is far from clear what the combined e ect of a...
Nested transactions in a logical language for active rules (1996)
Bertram Ludascher, Wolfgang May, Georg Lausen
Abstract. We present a hierarchically structured transaction-oriented concept for a rule-based active database system. In [LL94, LHL95], we have proposed Statelog as a unified framework for active...
Nested transactions in a logical language for active rules (1996)
Bertram Ludascher, Wolfgang May, Georg Lausen
Abstract. We present a hierarchically structured transaction-oriented concept for a rulebased active database system. In [LL94, LHL95], we have proposed Statelog as a unified framework for active and...
Nested Transactions in a Logical Language for Active Rules (1996)
Bertram Ludascher, Wolfgang May, Georg Lausen
Abstract. We present a hierarchically structured transaction-oriented concept for a rule-based active database system. In [LL94, LHL95], we have proposedStatelog as a uni ed framework for active and...
Logical foundations of object-oriented and frame-based languages (1995)
Michael Kifer, Georg Lausen, James Wu
We propose a novel formalism, called Frame Logic (abbr., F-logic), that accounts in a clean and declarative fashion for most of the structural aspects of object-oriented and frame-based languages....
A Logical Framework for Active Rules (1995)
Bertram Ludascher, Ulrich Hamann, Georg Lausen
We present a state-oriented extension to Datalog called Statelog which comprises two kinds of rules within a simple, yet flexible unified framework, i.e. (i) passive query rules used to express...
Reconciling Active and Deductive Databases by States (1995)
Bertram Ludäscher, Ulrich Hamann, Georg Lausen
We propose a state-oriented extension to Datalog called Statelog which comprises two kinds of rules, passive query rules and active transition rules within a simple, yet flexible logical framework....
Reconciling Active and Deductive Databases by (1995)
Abstract We propose a state-oriented extension to Datalog called Statelog which comprises two kinds of rules, passive query rules and active transition rules within a simple, yet flexible logical...
Access to objects by path expressions and rules (1994)
Jiirgen Frohn, Georg Lausen, Heinz Uphoff
Object oriented databases provide rich struc-turing capabilities to organise the objects being relevant for a given application. Due to the possible complexity of object structu-res, path expressions...
Access to objects by path expressions and rules (1994)
Jurgen Frohn, Georg Lausen, Heinz Uphoff
Object oriented databases provide rich structuring capabilities to organize the objects being relevant for a given application. Due to the possible complexity of object structures, path expressions...
Access to Objects by Path Expressions and Rules (1994)
Jürgen Frohn, Georg Lausen, Heinz Uphoff
Object oriented databases provide rich structuring capabilities to organize the objects being relevant for a given application. Due to the possible complexity of object structures, path expressions...
Abstract Access to Objects by Path Expressions and Rules (1994)
Jurgen Frohn, Georg Lausen, Heinz Upho, Jurgen Frohn Y
Object oriented databases provide rich structu-ring capabilities to organize the objects being re-levant for a given application. Due to the possi-ble complexity of object structures, path...
Updates in a Rule-Based Language for Objects (1992)
Michael Kramer, Georg Lausen, Gunter Saake
The integration of object-oriented concepts into deductive databases has been investigated for a certain time now. Various approaches to incorporate updates into deduction have been proposed. The...
Logical Foundations of Object-Oriented and Frame-Based Languages (1990)
Michael Kifer, Georg Lausen, James Wu
We propose a novel formalism, called Frame Logic (abbr., F-logic), that accounts in a clean and declarative fashion for most of the structural aspects of object-oriented and frame-based languages....
Logical Foundations of Object-Oriented and Frame-Based Languages (1990)
Michael Kifer Georg, Georg Lausen, James Wu
We propose a novel formalism, called Frame Logic (abbr., F-logic), that accounts in a clean and declarative fashion for most of the structural aspects of object-oriented and frame-based languages....
F-Logic: a higher-order language for reasoning about objects, inheritance, and scheme (1989)
We propose a database logic which accounts in a clean declarative fashion for most of the “object-oriented” features such as object identity, complex objects, inheritance, methods, etc....
Grundlagen einer netzorientierten Vorgehensweise für den konzeptuellen Datenbankentwurf / (1985)
Karlsruhe, Univ., Habil.-Schr., 1985 (Nicht für den Austausch).