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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  
We discuss work on the complexity of query languages for trees that was inseminated by our theoretical study of logic-based languages for wrapping.  ...  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.  ...  The program uses the intentional predicate, Italic, as the query predicate. 2 Monadic second-order logic (MSO) extends first-order logic by quantification over set variables, i.e., variables ranging over  ... 
doi:10.1145/1055558.1055560 dblp:conf/pods/GottlobKBHF04 fatcat:3ahbmitxyjd2fm447nn6523ica

Logic-based web information extraction

Georg Gottlob, Christoph Koch
2004 SIGMOD record  
Monadic second-order logic (MSO) over trees is a second-order logical language consisting of (1) individual variables ranging, (2) variables ranging over sets of nodes, (3) parentheses, (4) boolean connectives  ...  We assume unary queries in monadic second-order logic (MSO) over trees as our expressiveness yardstick for information extraction functions.  ... 
doi:10.1145/1024694.1024711 fatcat:6ogbizzxlnak3bbb4rif3irp64

Automata for XML—A survey

Thomas Schwentick
2007 Journal of computer and system sciences (Print)  
, querying and transformation.  ...  Automata play an important role for the theoretical foundations of XML data management, but also in tools for various XML processing tasks.  ...  A similarly fruitful interplay seems to exist for XML, this time by the different XML languages designed for various purposes, automata (and algebras) and monadic second-order logic and first-order logic  ... 
doi:10.1016/j.jcss.2006.10.003 fatcat:rhcckietinczlgoglqehlg2gza

XML query-update independence analysis revisited

Muhammad Junedi, Pierre Genevàs, Nabil Layaïda
2012 Proceedings of the 2012 ACM symposium on Document engineering - DocEng '12  
XML transformations can be resource-costly in particular when applied to very large XML documents and document sets.  ...  The essence of our approach and results resides in the use of an appropriate logic, to which queries and updates are both succinctly translated.  ...  Mondaic second order logic is equal in expressiveness to µ-logic [9] .  ... 
doi:10.1145/2361354.2361375 dblp:conf/doceng/JunediGL12 fatcat:ybqqt7bylng2tfvjwsctzvzgfy

Tree Transducers and Formal Methods (Dagstuhl Seminar 13192)

Sebastian Maneth, Helmut Seidl, Marc Herbstritt
2013 Dagstuhl Reports  
Recently, interest in tree transducers has been revived due to surprising new applications in areas such as XML databases, security verification, programming language theory, and linguistics.  ...  Recently, interest in tree transducers has been revived due to surprising new applications in areas such as XML databases, security verification, programming languages, and linguistics.  ...  This work has been presented in What features make the theory of a tree -say, the theory in monadic second-order logic (MSO) -decidable?  ... 
doi:10.4230/dagrep.3.5.1 dblp:journals/dagstuhl-reports/ManethS13 fatcat:xxotqpzgnzc3zdlkk4zxsdot5i

Value joins are expensive over (probabilistic) XML

Evgeny Kharlamov, Werner Nutt, Pierre Senellart
2011 Proceedings of the 4th International Workshop on Logic in Databases - LID '11  
Monadic second-order logic is a very propositional 2-DNF formula its number of satisfying assignments expressive query language on trees.  ...  We propose in this article a general study probabilistic XML, while for monadic second-order logic over trees of the complexity of query answering in both XML and probabilis- with joins  ... 
doi:10.1145/1966357.1966366 dblp:conf/lid/KharlamovNS11 fatcat:l5il7bxuffbvxgvva7bffbpojq

A Visual Query Language for Complex-Value Databases [article]

Christoph Koch
2006 arXiv   pre-print
In this paper, a visual language, VCP, for queries on complex-value databases is proposed.  ...  proper to logical, functional, or other database query languages and (ii) has a very natural, strong, and intuitive design metaphor.  ...  Ordered, unranked XML trees can be viewed as nested lists, but to get a visual language for XML with the expressive power of (full) monad algebra on lists, also tuple-typed nodes are required.  ... 
arXiv:cs/0602006v1 fatcat:3jt56b5z4vbcfcfsxde2y65wda

XML: Model, Schemas, Types, Logics, and Queries [chapter]

Nils Klarlund, Thomas Schwentick, Dan Suciu
2004 Logics for Emerging Applications of Databases  
We review these languages here emphasizing their automata-theoretic origin and their connection to monadic second order logic.  ...  The monadic-second-order (MSO) logic of such structures adds second-order variables interpreted as sets of nodes, along with quantification over these variables.  ... 
doi:10.1007/978-3-642-18690-5_1 fatcat:f5mtevnovffhnpfgdpb7rqlmji

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 start with a formal approach to web data extraction rooted in monadic second order logic and monadic Datalog, that gave rise to the Lixto data extraction system.  ...  This paper gives a short overview of specific logical approaches to data extraction, data management, and reasoning about data.  ...  However, XML 4 , a well-known language quite similar to HTML, allows one to impose a tree-shaped logical structure on data.  ... 
doi:10.1007/978-3-319-53733-7_2 fatcat:wkewt6kjpjezpnh44g4pak5kqe

Synchronous Parallel Database Transformations [chapter]

Klaus-Dieter Schewe, Qing Wang
2012 Lecture Notes in Computer Science  
Then the incorporation of weak monadic second-order logic provides an alternative computational model called XML machines.  ...  For the characterisation of XML database transformations the natural first step is therefore to define the appropriate tree-based backgrounds, which draw on hereditarily finite trees, tree algebra operations  ...  Section 4 introduces a weak monadic second-order logic, which adds further requirements to tree-based backgrounds.  ... 
doi:10.1007/978-3-642-28472-4_21 fatcat:2hjtynvwj5cdtpwqgdhpmrhowi

Optimising XML–RDF Data Integration [chapter]

Stefan Bischof
2012 Lecture Notes in Computer Science  
The query language XSPARQL, which is built by combining XQuery and SPARQL, addresses some of these problems.  ...  XML remains a widespread format for data exchange. When combining data of these two formats several problems arise due to representational incompatibilities.  ...  Other approaches [2, 6, 7, 10, 11] map XQuery to standard logics (Datalog/logic programming, monadic second order logic) in order to profit from well studied properties.  ... 
doi:10.1007/978-3-642-30284-8_67 fatcat:drft3r727fhjziow6gyso3ktfa

On reasoning about structural equality in XML: a description logic approach

David Toman, Grant Weddell
2005 Theoretical Computer Science  
This application depends on the novel ability of DLFD reg to express functional dependencies over possibly infinite sets of feature paths defined by regular languages.  ...  We define a boolean complete dialect of description logic called DLFD reg that can be used to reason about structural equality in semistructured ordered data in the presence of document type definitions  ...  Our formulation is based on the common practice of interpreting an XML document or a document collection as an ordered forest of rooted node-labeled ordered trees. (XML forests and trees) .  ... 
doi:10.1016/j.tcs.2004.10.036 fatcat:g54fwoqbafab5nx42kylomjglq

On Reasoning about Structural Equality in XML: A Description Logic Approach [chapter]

David Toman, Grant Weddell
2002 Lecture Notes in Computer Science  
This application depends on the novel ability of DLFD reg to express functional dependencies over possibly infinite sets of feature paths defined by regular languages.  ...  We define a boolean complete dialect of description logic called DLFD reg that can be used to reason about structural equality in semistructured ordered data in the presence of document type definitions  ...  Our formulation is based on the common practice of interpreting an XML document or a document collection as an ordered forest of rooted node-labeled ordered trees. (XML forests and trees) .  ... 
doi:10.1007/3-540-36285-1_7 fatcat:ez65w4jy2fbxhmkzhkz7dz4p7u

Automata- and Logic-Based Pattern Languages for Tree-Structured Data [chapter]

Frank Neven, Thomas Schwentick
2003 Lecture Notes in Computer Science  
This paper surveys work of the authors on pattern languages for tree-structured data with XML as the main application in mind. The main focus is on formalisms from formal language theory and logic.  ...  In particular, it considers attribute grammars, query automata, treewalking automata, extensions of first-order logic, and monadic secondorder logic.  ...  However, when searching for a natural logic on trees there is one obvious candidate that was well investigated already 30 years ago: monadic second-order logic (MSO).  ... 
doi:10.1007/3-540-36596-6_9 fatcat:647wylabnjfshdr6opbrzxflna

Web Data Extraction System [chapter]

Robert Baumgartner, Wolfgang Gatterbauer, Georg Gottlob
2016 Encyclopedia of Database Systems  
The predicates can be defined either by logical formulas, or by logic programs such as monadic datalog, which was shown to be equivalent in expressive power to monadic second-order logic (MSO) [6] .  ...  VD is based on Eclipse and embeds the Mozilla browser. Kapowtech.  ... 
doi:10.1007/978-1-4899-7993-3_1154-2 fatcat:6ghtb2rgjzgfvmm5kpah7lcm5e
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