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Logic, Languages, and Rules for Web Data Extraction and Reasoning over Data [chapter]

Georg Gottlob, Christoph Koch, Andreas Pieris
2017 Lecture Notes in Computer Science  
We then present some complexity results for monadic Datalog over trees and for XPath query evaluation.  ...  We give an overview of important members of this family and discuss related complexity issues.  ...  With some minor additions, monadic Datalog can be used to simulate the core fragment of XPath [22] , which indicates that core XPath is not more complex than monadic Datalog.  ... 
doi:10.1007/978-3-319-53733-7_2 fatcat:wkewt6kjpjezpnh44g4pak5kqe

The Lixto data extraction project

Georg Gottlob, Christoph Koch, Robert Baumgartner, Marcus Herzog, Sergio Flesca
2004 Proceedings of the twenty-third ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems - PODS '04  
Then we present theoretical results on monadic datalog over trees and on Elog, its close relative which is used as the internal wrapper language in the Lixto system.  ...  These results include both a characterization of the expressive power and the complexity of these languages.  ...  In [15] , we introduced Core XPath, the navigational fragment of XPath, which includes both horizontal and vertical tree navigation with axes, node tests, and boolean combinations of condition predicates  ... 
doi:10.1145/1055558.1055560 dblp:conf/pods/GottlobKBHF04 fatcat:3ahbmitxyjd2fm447nn6523ica

XPath-Logic and XPathLog: A Logic-Programming Style XML Data Manipulation Language [article]

Wolfgang May
2003 arXiv   pre-print
XPath-Logic extends the XPath language with variable bindings and embeds it into first-order logic.  ...  The model-theoretic semantics of XPath-Logic serves as the base of XPathLog as a logic-programming language, whereas also an equivalent answer-set semantics for evaluating XPathLog queries is given.  ...  Most of this work has been done when I was a member of the database group at Freiburg University.  ... 
arXiv:cs/0311038v1 fatcat:zt5rzi45gbexrnglgqafu5k5je

Processing queries on tree-structured data efficiently

Christoph Koch
2006 Proceedings of the twenty-fifth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems - PODS '06  
I focus on query languages that compute nodes or tuples of nodes -conjunctive queries, first-order queries, datalog, and XPath.  ...  The techniques belong to five groups: 1. employing orders on the nodes of the tree for efficient labeling schemes and structural joins, 2. linear-time algorithms for evaluating Horn-SAT (the datalog technique  ...  Unfortunately, the positive result on the parallel complexity of positive XPath does not even extend to Core XPath (with negation): Core XPath is PTime-hard (combined complexity) [34] .  ... 
doi:10.1145/1142351.1142382 dblp:conf/pods/Koch06 fatcat:2zanpmquibamjkr2m45dfpgngq

XPlainer-Eclipse

John W. S. Liu, Mariano P. Consens, Flavio Rizzolo
2006 Proceedings of the 2006 OOPSLA workshop on eclipse technology eXchange - eclipse '06  
XPlainer-Eclipse combines editors for visualizing both XML documents and XPath expressions as trees together with the explanation of the answers.  ...  Example tools include debuggers that return the result of XPath subexpressions visualized in the context of the input XML document.  ...  Acknowledgments Portions of this work were carried out in collaboration with Dr. Bill O'Farrell and Julie Waterhouse at the IBM Centre for Advanced Studies. We would also like to thank Dr.  ... 
doi:10.1145/1188835.1188852 dblp:conf/eclipse/LiuCR06 fatcat:weab5vhalnbdlfxbqlldyr6wrm

EDUTELLA

Wolfgang Nejdl, Boris Wolf, Changtao Qu, Stefan Decker, Michael Sintek, Ambjörn Naeve, Mikael Nilsson, Matthias Palmér, Tore Risch
2002 Proceedings of the eleventh international conference on World Wide Web - WWW '02  
As the query service is one of the core services of Edutella, upon which other services are built, we specify in detail the Edutella Common Data Model (ECDM) as basis for the Edutella query exchange language  ...  In this paper we discuss the open source project Edutella which builds upon metadata standards defined for the WWW and aims to provide an RDFbased metadata infrastructure for P2P applications, building  ...  This paper is based on a lot of fruitful discussions with participants within the PADLR projects.  ... 
doi:10.1145/511446.511525 dblp:conf/www/NejdlWQDSNNPR02 fatcat:qfdnn2lsqvgytknxkx425f3c2m

EDUTELLA

Wolfgang Nejdl, Boris Wolf, Changtao Qu, Stefan Decker, Michael Sintek, Ambjörn Naeve, Mikael Nilsson, Matthias Palmér, Tore Risch
2002 Proceedings of the eleventh international conference on World Wide Web - WWW '02  
As the query service is one of the core services of Edutella, upon which other services are built, we specify in detail the Edutella Common Data Model (ECDM) as basis for the Edutella query exchange language  ...  In this paper we discuss the open source project Edutella which builds upon metadata standards defined for the WWW and aims to provide an RDFbased metadata infrastructure for P2P applications, building  ...  This paper is based on a lot of fruitful discussions with participants within the PADLR projects.  ... 
doi:10.1145/511523.511525 fatcat:az72hps3vzcc3iflnhgtcssapi

XPlainer: Visual Explanations of XPath Queries

Mariano P. Consens, John W. S. Liu, Flavio Rizzolo
2007 2007 IEEE 23rd International Conference on Data Engineering  
The XPlainer-Eclipse tool is built on an extensible development environment that includes editors for visualizing both XML documents and XPath expressions as trees together with the explanation of the  ...  This enables the use of XPath engines for the evaluation of explanation queries. We describe a tool that uses XPlainer queries to provide visual explanations.  ...  Given an XPath query and an input XML document, an explanation of the query gives as answer all the XPath result nodes together with intermediate nodes.  ... 
doi:10.1109/icde.2007.367909 dblp:conf/icde/ConsensLR07 fatcat:ppu6dckzqbe6nk5prm2lsgkwsm

Containment of Monadic Datalog Programs via Bounded Clique-Width [chapter]

Mikołaj Bojańczyk, Filip Murlak, Adam Witkowski
2015 Lecture Notes in Computer Science  
Containment of monadic datalog programs over data trees (labelled trees with an equivalence relation) is undecidable.  ...  As a step towards these goals, complexity of containment over arbitrary structures of bounded clique-width is analysed: satisfiability and containment of monadic programs with stratified negation is in  ...  Extend σ ext with a fresh unary relation H.  ... 
doi:10.1007/978-3-662-47666-6_34 fatcat:w76f4sqiu5fgljindq67ubzteu

Provenance Circuits for Trees and Treelike Instances [chapter]

Antoine Amarilli, Pierre Bourhis, Pierre Senellart
2015 Lecture Notes in Computer Science  
This tractability result has been extended to several tasks related to query evaluation, such as counting query results [3] or performing query evaluation on probabilistic trees [10].  ...  intrinsic definitions of provenance for general semirings, independent of the operational details of query evaluation.  ...  Datalog queries are defined over an extended signature with additional predicate symbols, called IDB predicates; all other predicates are called EDB predicates.  ... 
doi:10.1007/978-3-662-47666-6_5 fatcat:dpatpbav7fgblnbvfsx6dbr6k4

Logic-based web information extraction

Georg Gottlob, Christoph Koch
2004 SIGMOD record  
Z29-N04 and the GAMES Network of Excellence of the European Union.  ...  For example, Core XPath [17] , the logical core fragment of the popular XPath language, can be mapped efficiently to monadic datalog [14, 9] and thus inherits its very favorable worst-case evaluation  ...  A unary MSO query is defined by an MSO formula ϕ with one free first-order variable. Given a tree t, it evaluates to the set of nodes {x ∈ dom | t ϕ(x)}.  ... 
doi:10.1145/1024694.1024711 fatcat:6ogbizzxlnak3bbb4rif3irp64

Four Lessons in Versatility or How Query Languages Adapt to the Web [chapter]

François Bry, Tim Furche, Benedikt Linse, Alexander Pohl, Antonius Weinzierl, Olga Yestekhina
2009 Lecture Notes in Computer Science  
This fracturing stifles innovation as application builders have to cope not only with one Web stack (e.g., XML technology) but with several ones, each of considerable complexity.  ...  Nevertheless, we also give a unified evaluation approach based on interval labelings of graphs that is at least as fast as existing approaches for tree-shaped XML data, yet provides linear time and space  ...  While path expressions in XPATH evaluate to a set of nodes of an XML document, path expressions in nSPARQL evaluate to a set of pairs of nodes within of an RDF graph.  ... 
doi:10.1007/978-3-642-04581-3_2 fatcat:tyjxlcot7bgztckkzfw6vqq24m

XML-to-SQL Query Translation Literature: The State of the Art and Open Problems [chapter]

Rajasekar Krishnamurthy, Raghav Kaushik, Jeffrey F. Naughton
2003 Lecture Notes in Computer Science  
Recently, the database research literature has seen an explosion of publications with the goal of using an RDBMS to store and/or query XML data.  ...  (with the // axis) into SQL when the XML schema is recursive.  ...  -Evaluating an XML query by composing it with the view.  ... 
doi:10.1007/978-3-540-39429-7_1 fatcat:4tyqj4mp3neohe4hxr4cnuwj7q

The Query Translation Landscape: a Survey [article]

Mohamed Nadjib Mami, Damien Graux, Harsh Thakkar, Simon Scerri, Sören Auer, Jens Lehmann
2019 arXiv   pre-print
Achieving interoperability through the full transformation and integration of diverse data structures remains an ideal that is hard, if not impossible, to achieve.  ...  The lack of data interoperability limits the potential of its collective use for novel applications.  ...  XPath queries with the extended expressions can, next, be translated into an equivalent sequence of SQL queries using a common RDBMS operator (LFP: Simple Least Fixpoint).  ... 
arXiv:1910.03118v1 fatcat:wsww5vhlwjhqjlouibetb6mo3a

Forward node-selecting queries over trees

Dan Olteanu
2007 ACM Transactions on Database Systems  
This work is devoted to an expressiveness study of node-selecting queries with proven theoretical and practical applicability, especially in the field of query evaluation against XML streams.  ...  The main question it answers positively is whether for each input query with forward and backward predicates there exists an equivalent forward-only output query.  ...  Rather than dealing with XPath syntax, this framework uses an equivalent fragment of monadic non-recursive Datalog with negation [Abiteboul et al. 1995] and with built-in predicates for the XPath axes  ... 
doi:10.1145/1206049.1206052 fatcat:qqruq5qqvzc5rdgbgn7ry5ahyu
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