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Semi-rational Sets of DAGs [chapter]

Lutz Priese
2005 Lecture Notes in Computer Science  
It is shown that the class of semi-rational sets of DAGs coincides with the synchronization closure of Courcelles class of recognizable sets of unranked, unordered trees (or forests).  ...  We call a set of DAGs (directed acyclic graphs) semi-rational if it is accepted by a Petri net.  ...  In this paper, the terms tree, forest, DAG, and graph always refer to finite, directed, node labelled, unranked and unordered trees, forests, DAGs, or graphs.  ... 
doi:10.1007/11505877_34 fatcat:x6v7gqanrnbm7k7cosxtehsqxi

DAG Automata for Meaning Representation

Frank Drewes
2017 Proceedings of the 15th Meeting on the Mathematics of Language  
This paper gives an overview of recent results on a family of automata recognizing such DAG languages.  ...  Languages of directed acyclic graphs (DAGs) are of interest in Natural Language Processing because they can be used to capture the structure of semantic graphs like those of Abstract Meaning Representation  ...  Acknowledgments I thank everyone who contributed to the work on DAG automata either directly or by discussing ideas and providing opinions at various occasions.  ... 
doi:10.18653/v1/w17-3409 dblp:conf/mol/Drewes17 fatcat:en7wqw4cmbf47pqzal77k5gdlm

Formal Models of Graph Transformation in Natural Language Processing (Dagstuhl Seminar 15122)

Frank Drewes, Kevin Knight, Marco Kuhlmann, Marc Herbstritt
2015 Dagstuhl Reports  
that one faces when applying the theory of graph transformation to NLP problems.  ...  languages, concurrent processes, and software engineering.  ...  Meaning-representing DAGs are usually unranked in the sense that there is no a priori bound on the number of incoming and outgoing edges of a node.  ... 
doi:10.4230/dagrep.5.3.143 dblp:journals/dagstuhl-reports/DrewesKK15 fatcat:jepncn4wmvanviyxqlexozltm4

Monadic Datalog Containment on Trees [article]

André Frochaux and Martin Grohe and Nicole Schweikardt
2014 arXiv   pre-print
We show that the query containment problem for monadic datalog on finite unranked labeled trees can be solved in 2-fold exponential time when (a) considering unordered trees using the axes child and descendant  ...  , and when (b) considering ordered trees using the axes firstchild, nextsibling, child, and descendant.  ...  The first author would like to thank Mariano Zelke for countless inspiring discussions and helpful hints on and off the topic.  ... 
arXiv:1404.0606v1 fatcat:zwru7wxi5jcg5akfutxlpykofq

Approximate schemas, source-consistency and query answering

Michel de Rougemont, Adrien Vieilleribière
2008 Journal of Intelligent Information Systems  
We use the Edit distance with Moves on words and trees and say that two regular (tree) languages are ε-close if every word (tree) of one language is ε-close to the other.  ...  Using the statistical embedding of [8], we show that Source-Consistency and Approximate Query Answering are testable on words and trees, i.e. can be approximately decided within ε by only looking at a  ...  An unranked unordered tree is a structure T = (D n , Child, root) with no order on the siblings.  ... 
doi:10.1007/s10844-008-0060-9 fatcat:vwch5mpa4jhm5owh3k7umfetja

Weighted DAG Automata for Semantic Graphs

David Chiang, Frank Drewes, Daniel Gildea, Adam Lopez, Giorgio Satta
2018 Computational Linguistics  
A deficit in this area of research is a formal framework for creating, combining, and using models involving graphs that parallels the frameworks of finite automata for strings and finite tree automata  ...  In this article, we study the latter in depth, demonstrating several new results, including a practical recognition algorithm that can be used for inference and learning with models defined on DAG automata  ...  Acknowledgments We are grateful to the anonymous reviewers for their useful suggestions and to Sorcha Gilroy  ... 
doi:10.1162/coli_a_00309 fatcat:sjj5cfnrpng4dfxdrqs3opogem

Grammar-Based Compression of Unranked Trees [chapter]

Adrià Gascón, Markus Lohrey, Sebastian Maneth, Carl Philipp Reh, Kurt Sieber
2018 Lecture Notes in Computer Science  
We compare the succinctness of FSLPs with two other compression schemes for unranked trees: top dags and tree straight-line programs of firstchild/next sibling encodings.  ...  FSLPs are based on the operations of forest algebra and generalize tree straight-line programs.  ...  ordinary tree automata on binary trees.  ... 
doi:10.1007/978-3-319-90530-3_11 fatcat:hd53iqy6pzdjzgumcoajp6wprq

XML tree structure compression using RePair

Markus Lohrey, Sebastian Maneth, Roy Mennicke
2013 Information Systems  
XML tree structures can conveniently be represented using ordered unranked trees.  ...  While minimal SLCF tree grammars are in general smaller than minimal DAGs, they cannot be computed in polynomial time unless P = NP.  ...  The complexity of several algorithms on SLCF tree grammars (such as evaluating tree automata) depend on the number of parameters in the grammar [22] .  ... 
doi:10.1016/j.is.2013.06.006 fatcat:2cf7kfmp6ned7pxqsnagiy4cwe

Approximate Data Exchange [chapter]

Michel de Rougemont, Adrien Vieilleribière
2006 Lecture Notes in Computer Science  
We consider a model based on transducers of words and trees, and study ε-Consistency, i.e., the problem of deciding whether a given source instance I is -close to a source I , whose image by a transducer  ...  We introduce approximate data exchange, by relaxing classical data exchange problems such as Consistency and Typechecking to their approximate versions based on Property Testing.  ...  We showed that for the Edit distance with Moves, ε-Source-consistency is testable on words and trees, and that ε-Typechecking is polynomial on words.  ... 
doi:10.1007/11965893_4 fatcat:yd4slxwoojgvzka7mdx356ulwa

Typechecking for XML transformers

Tova Milo, Dan Suciu, Victor Vianu
2003 Journal of computer and system sciences (Print)  
We model XML transformers using a novel device called a k-pebble transducer, that can express most queries without data-value joins in XML-QL, XSLT, and other XML query languages.  ...  We study the typechecking problem for XML (eXtensible Markup Language) transformers: given an XML transformation program and a DTD for the input XML documents, check whether every result of the program  ...  Thanks also to Thomas Schwentick for pointing out the connection between k-pebble automata and star-free generalized regular expressions, yielding the lower bound in Theorem 4.8.  ... 
doi:10.1016/s0022-0000(02)00030-2 fatcat:a2bxrrse3vf2pha25mrbwnaulu

Typechecking for XML transformers

Tova Milo, Dan Suciu, Victor Vianu
2000 Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems - PODS '00  
We model XML transformers using a novel device called a k-pebble transducer, that can express most queries without data-value joins in XML-QL, XSLT, and other XML query languages.  ...  We study the typechecking problem for XML (eXtensible Markup Language) transformers: given an XML transformation program and a DTD for the input XML documents, check whether every result of the program  ...  Thanks also to Thomas Schwentick for pointing out the connection between k-pebble automata and star-free generalized regular expressions, yielding the lower bound in Theorem 4.8.  ... 
doi:10.1145/335168.335171 dblp:conf/pods/MiloSV00 fatcat:hc2feri2lvetnoduhkntza2lwu

Decidable Classes of Tree Automata Mixing Local and Global Constraints Modulo Flat Theories

Luis Barguñó, Carles Creus, Guillem Godoy, Florent Jacquemard, Camille Vacher, Thomas Schwentick
2013 Logical Methods in Computer Science  
We define a class of ranked tree automata TABG generalizing both the tree automata with local tests between brothers of Bogaert and Tison (1992) and with global equality and disequality constraints (TAGED  ...  We also adapt the model to unranked ordered terms.  ...  Acknowledgement We thank Luc Segoufin for many valuable discussions and the anonymous referees at LICS 2010 for their useful comments and suggestions.  ... 
doi:10.2168/lmcs-9(2:1)2013 fatcat:jl4thcpqzbafteoajs6pe22vri

Expressiveness and complexity of xml publishing transducers

Wenfei Fan, Floris Geerts, Frank Neven
2007 Proceedings of the twenty-sixth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems - PODS '07  
Unlike automata for querying XML data, a publishing transducer generates a new XML tree rather than performing a query on an existing tree.  ...  We study a variety of publishing transducers based on what relational queries a transducer can issue, what temporary stores a transducer can use during tree generation, and whether or not some tree nodes  ...  We thank Michael Benedikt, Christoph Koch and Leonid Libkin for helpful discussions. Wenfei Fan is supported in part by EPSRC GR/S63205/01, GR/T27433/01 and BBSRC BB/D006473/1.  ... 
doi:10.1145/1265530.1265542 dblp:conf/pods/FanGN07 fatcat:6mpdqlemlzdqzbjdghmaddid6i

Compressed Tree Canonization [chapter]

Markus Lohrey, Sebastian Maneth, Fabian Peternek
2015 Lecture Notes in Computer Science  
A good example is the membership problem for tree automata (PTIME-complete for SLT grammars [17] and PSPACE-complete for ST grammars [15]).  ...  problem for (rooted or unrooted) unordered trees that are given by ST grammars is PSPACE-hard and in EXPTIME.  ...  Hardness for PTIME follows from the PTIME-hardness for dags [18] and the fact that isomorphism of rooted unordered trees can be reduced to isomorphism of unrooted unordered trees by labelling the roots  ... 
doi:10.1007/978-3-662-47666-6_27 fatcat:cmcveqijfzdibaafnpzcfrjnhe

Verification of Directed Acyclic Ad Hoc Networks [chapter]

Parosh Aziz Abdulla, Mohamed Faouzi Atig, Othmane Rezine
2013 Lecture Notes in Computer Science  
The processes are finite-state machines with local and synchronized broadcast transitions. Reception of a broadcast is restricted to the immediate neighbors of the sender process.  ...  The underlying connectivity graph constrains communication pattern to only one direction.  ...  Intuitively, we can view an extended configuration as an inverted tree that is unranked (a node may have any number of predecessors) and unordered (the order in which the predecessors occur is not relevant  ... 
doi:10.1007/978-3-642-38592-6_14 fatcat:uoqgevkqszegzmwayc7odn2gwm
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