TY  - CHAP
A1  - Curzon, Paul
A1  - Kalas, Ivan
A1  - Schubert, Sigrid
A1  - Schaper, Niclas
A1  - Barnes, Jan
A1  - Kennewell, Steve
A1  - Bröker, Kathrin
A1  - Kastens, Uwe
A1  - Magenheim, Johannes
A1  - Dagiene, Valentina
A1  - Stupuriene, Gabriele
A1  - Ellis, Jason Brent
A1  - Abreu-Ellis, Carla Reis
A1  - Grillenberger, Andreas
A1  - Romeike, Ralf
A1  - Haugsbakken, Halvdan
A1  - Jones, Anthony
A1  - Lewin, Cathy
A1  - McNicol, Sarah
A1  - Nelles, Wolfgang
A1  - Neugebauer, Jonas
A1  - Ohrndorf, Laura
A1  - Schaper, Niclas
A1  - Schubert, Sigrid
A1  - Opel, Simone
A1  - Kramer, Matthias
A1  - Trommen, Michael
A1  - Pottbäcker, Florian
A1  - Ilaghef, Youssef
A1  - Passig, David
A1  - Tzuriel, David
A1  - Kedmi, Ganit Eshel
A1  - Saito, Toshinori
A1  - Webb, Mary
A1  - Weigend, Michael
A1  - Bottino, Rosa
A1  - Chioccariello, Augusto
A1  - Christensen, Rhonda
A1  - Knezek, Gerald
A1  - Gioko, Anthony Maina
A1  - Angondi, Enos Kiforo
A1  - Waga, Rosemary
A1  - Ohrndorf, Laura
A1  - Or-Bach, Rachel
A1  - Preston, Christina
A1  - Younie, Sarah
A1  - Przybylla, Mareen
A1  - Romeike, Ralf
A1  - Reynolds, Nicholas
A1  - Swainston, Andrew
A1  - Bendrups, Faye
A1  - Sysło, Maciej M.
A1  - Kwiatkowska, Anna Beata
A1  - Zieris, Holger
A1  - Gerstberger, Herbert
A1  - Müller, Wolfgang
A1  - Büchner, Steffen
A1  - Opel, Simone
A1  - Schiller, Thomas
A1  - Wegner, Christian
A1  - Zender, Raphael
A1  - Lucke, Ulrike
A1  - Diethelm, Ira
A1  - Syrbe, Jörn
A1  - Lai, Kwok-Wing
A1  - Davis, Niki
A1  - Eickelmann, Birgit
A1  - Erstad, Ola
A1  - Fisser, Petra
A1  - Gibson, David
A1  - Khaddage, Ferial
A1  - Knezek, Gerald
A1  - Micheuz, Peter
A1  - Kloos, Carlos Delgado
ED  - Brinda, Torsten
ED  - Reynolds, Nicholas
ED  - Romeike, Ralf
ED  - Schwill, Andreas
T1  - KEYCIT 2014
BT  - key competencies in informatics and ICT
N2  - In our rapidly changing world it is increasingly important not only to be an expert in a chosen field of study but also to be able to respond to developments, master new approaches to solving problems, and fulfil changing requirements in the modern world and in the job market. In response to these needs key competencies in understanding, developing and using new digital technologies are being brought into focus in school and university programmes. The IFIP TC3 conference "KEYCIT – Key Competences in Informatics and ICT (KEYCIT 2014)" was held at the University of Potsdam in Germany from July 1st to 4th, 2014 and addressed the combination of key competencies, Informatics and ICT in detail. The conference was organized into strands focusing on secondary education, university education and teacher education (organized by IFIP WGs 3.1 and 3.3) and provided a forum to present and to discuss research, case studies, positions, and national perspectives in this field.
T3  - Commentarii informaticae didacticae (CID) - 7 
KW  - Schlüsselkompetenzen
KW  - Informatik
KW  - Bildung
KW  - ICT
KW  - Informatikdidaktik
KW  - Key Competencies
KW  - Informatics
KW  - education
KW  - ICT
KW  - Computer Science Education
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-70325
SN  - 978-3-86956-292-6
PB  - Universitätsverlag Potsdam
CY  - Potsdam
ER  - 
TY  - CHAP
A1  - Hofuku, Yayoi
A1  - Cho, Shinya
A1  - Nishida, Tomohiro
A1  - Kanemune, Susumu
A1  - Linck, Barbara
A1  - Kim, Seungyon
A1  - Park, Seongbin
A1  - Vaníček, Jiří
A1  - Gujberová, Monika
A1  - Tomcsányi, Peter
A1  - Dagiene, Valentina
A1  - Jevsikova, Tatjana
A1  - Schulte, Carsten
A1  - Sentance, Sue
A1  - Thota, Neena
A1  - Gülbahar, Yasemin
A1  - İlkhan, Mustafa
A1  - Kilis, Selcan
A1  - Arslan, Okan
A1  - Nakano, Yoshiaki
A1  - Izutsu, Katsunobu
A1  - Lessner, Daniel
A1  - Reffay, Christophe
A1  - Miled, Mahdi
A1  - Ortiz, Pascal
A1  - Février, Loïc
A1  - Grgurina, Nataša
A1  - Weise, Martin
A1  - Bellettini, Carlo
A1  - Lonati, Violetta
A1  - Malchiodi, Dario
A1  - Monga, Mattia
A1  - Morpurgo, Anna
A1  - Torelli, Mauro
A1  - Planteu, Lukas
A1  - Standl, Bernhard
A1  - Grossmann, Wilfried
A1  - Neuwirth, Erich
A1  - Benacka, Jan
A1  - Ragonis, Noa
A1  - Hodges, Steve
A1  - Berry, Carol
A1  - Kusterer, Peter
ED  - Diethelm, Ira
ED  - Arndt, Jannik
ED  - Dünnebier, Malte
ED  - Syrbe, Jörn
T1  - Informatics in schools : local proceedings of the 6th International Conference ISSEP 2013 ; selected papers ; Oldenburg, Germany, February 26–March 2, 2013
N2  - The International Conference on Informatics in Schools: Situation, Evolution and Perspectives – ISSEP – is a forum for researchers and practitioners in the area of Informatics education, both in primary and secondary schools. It provides an opportunity for educators to reflect upon the goals and objectives of this subject, its curricula and various teaching/learning paradigms and topics, possible connections to everyday life and various ways of establishing Informatics Education in schools. This conference also cares about teaching/learning materials, various forms of assessment, traditional and innovative educational research designs, Informatics’ contribution to the preparation of children for the 21st century, motivating competitions, projects and activities supporting informatics education in school.
T3  - Commentarii informaticae didacticae (CID) - 6 
KW  - ISSEP
KW  - Informatics Education
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-63688
SN  - 978-3-86956-222-3
PB  - Universitätsverlag Potsdam
CY  - Potsdam
ER  - 
TY  - CHAP
A1  - Banda, Gourinath
A1  - Gallagher, John P.
T1  - Constraint-based abstraction of a model checker for infinite state systems
N2  - Abstract interpretation-based model checking provides an approach to verifying properties of infinite-state systems. In practice, most previous work on abstract model checking is either restricted to verifying universal properties, or develops special techniques for temporal logics such as modal transition systems or other dual transition systems. By contrast we apply completely standard techniques for constructing abstract interpretations to the abstraction of a CTL semantic function, without restricting the kind of properties that can be verified. Furthermore we show that this leads directly to implementation of abstract model checking algorithms for abstract domains based on constraints, making use of an SMT solver.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41516
ER  - 
TY  - CHAP
A1  - Goltz, Hans-Joachim
A1  - Pieth, Norbert
T1  - A tool for generating partition schedules of multiprocessor systems
N2  - A deterministic cycle scheduling of partitions at the operating system level is supposed for a multiprocessor system. In this paper, we propose a tool for generating such schedules. We use constraint based programming and develop methods and concepts for a combined interactive and automatic partition scheduling system. This paper is also devoted to basic methods and techniques for modeling and solving this partition scheduling problem. Initial application of our partition scheduling tool has proved successful and demonstrated the suitability of the methods used.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41556
ER  - 
TY  - CHAP
A1  - Schrijvers, Tom
T1  - Overview of the monadic constraint programming framework
N2  - A constraint programming system combines two essential components: a constraint solver and a search engine. The constraint solver reasons about satisfiability of conjunctions of constraints, and the search engine controls the search for solutions by iteratively exploring a disjunctive search tree defined by the constraint program. The Monadic Constraint Programming framework gives a monadic definition of constraint programming where the solver is defined as a monad threaded through the monadic search tree. Search and search strategies can then be defined as firstclass objects that can themselves be built or extended by composable search transformers. Search transformers give a powerful and unifying approach to viewing search in constraint programming, and the resulting constraint programming system is first class and extremely flexible.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41411
ER  - 
TY  - CHAP
A1  - Herre, Heinrich
A1  - Hummel, Axel
T1  - Stationary generated models of generalized logic programs
N2  - The interest in extensions of the logic programming paradigm beyond the class of normal logic programs is motivated by the need of an adequate representation and processing of knowledge. One of the most difficult problems in this area is to find an adequate declarative semantics for logic programs. In the present paper a general preference criterion is proposed that selects the ‘intended’ partial models of generalized logic programs which is a conservative extension of the stationary semantics for normal logic programs of [Prz91]. The presented preference criterion defines a partial model of a generalized logic program as intended if it is generated by a stationary chain. It turns out that the stationary generated models coincide with the stationary models on the class of normal logic programs. The general wellfounded semantics of such a program is defined as the set-theoretical intersection of its stationary generated models. For normal logic programs the general wellfounded semantics equals the wellfounded semantics.
KW  - extensions of logic programs
KW  - semantics
KW  - knowledge representation
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41501
ER  - 
TY  - CHAP
A1  - Abdennadher, Slim
A1  - Ismail, Haythem
A1  - Khoury, Frederick
T1  - Transforming imperative algorithms to constraint handling rules
N2  - Different properties of programs, implemented in Constraint Handling Rules (CHR), have already been investigated. Proving these properties in CHR is fairly simpler than proving them in any type of imperative programming language, which triggered the proposal of a methodology to map imperative programs into equivalent CHR. The equivalence of both programs implies that if a property is satisfied for one, then it is satisfied for the other. The mapping methodology could be put to other beneficial uses. One such use is the automatic generation of global constraints, at an attempt to demonstrate the benefits of having a rule-based implementation for constraint solvers.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41533
ER  - 
TY  - CHAP
A1  - Betz, Hariolf
A1  - Raiser, Frank
A1  - Frühwirth, Thom
T1  - Persistent constraints in constraint handling rules
N2  - In the most abstract definition of its operational semantics, the declarative and concurrent programming language CHR is trivially non-terminating for a significant class of programs. Common refinements of this definition, in closing the gap to real-world implementations, compromise on declarativity and/or concurrency. Building on recent work and the notion of persistent constraints, we introduce an operational semantics avoiding trivial non-termination without compromising on its essential features.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41547
ER  - 
TY  - CHAP
A1  - Gebser, Martin
A1  - Hinrichs, Henrik
A1  - Schaub, Torsten H.
A1  - Thiele, Sven
T1  - xpanda: a (simple) preprocessor for adding multi-valued propositions to ASP
N2  - We introduce a simple approach extending the input language of Answer Set Programming (ASP) systems by multi-valued propositions. Our approach is implemented as a (prototypical) preprocessor translating logic programs with multi-valued propositions into logic programs with Boolean propositions only. Our translation is modular and heavily benefits from the expressive input language of ASP. The resulting approach, along with its implementation, allows for solving interesting constraint satisfaction problems in ASP, showing a good performance.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41466
ER  - 
TY  - CHAP
A1  - Oetsch, Johannes
A1  - Schwengerer, Martin
A1  - Tompits, Hans
T1  - Kato: a plagiarism-detection tool for answer-set programs
N2  - We present the tool Kato which is, to the best of our knowledge, the first tool for plagiarism detection that is directly tailored for answer-set programming (ASP). Kato aims at finding similarities between (segments of) logic programs to help detecting cases of plagiarism. Currently, the tool is realised for DLV programs but it is designed to handle various logic-programming syntax versions. We review basic features and the underlying methodology of the tool.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41485
ER  - 
TY  - CHAP
A1  - Zhou, Neng-Fa
T1  - What I have learned from all these solver competitions
N2  - In this talk, I would like to share my experiences gained from participating in four CSP solver competitions and the second ASP solver competition. In particular, I’ll talk about how various programming techniques can make huge differences in solving some of the benchmark problems used in the competitions. These techniques include global constraints, table constraints, and problem-specific propagators and labeling strategies for selecting variables and values. I’ll present these techniques with experimental results from B-Prolog and other CLP(FD) systems.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41431
ER  - 
TY  - CHAP
A1  - Hanus, Michael
A1  - Koschnicke, Sven
T1  - An ER-based framework for declarative web programming
N2  - We describe a framework to support the implementation of web-based systems to manipulate data stored in relational databases. Since the conceptual model of a relational database is often specified as an entity-relationship (ER) model, we propose to use the ER model to generate a complete implementation in the declarative programming language Curry. This implementation contains operations to create and manipulate entities of the data model, supports authentication, authorization, session handling, and the composition of individual operations to user processes. Furthermore and most important, the implementation ensures the consistency of the database w.r.t. the data dependencies specified in the ER model, i.e., updates initiated by the user cannot lead to an inconsistent state of the database. In order to generate a high-level declarative implementation that can be easily adapted to individual customer requirements, the framework exploits previous works on declarative database programming and web user interface construction in Curry.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41447
ER  - 
TY  - CHAP
A1  - Geske, Ulrich
A1  - Wolf, Armin
T1  - Preface
N2  - The workshops on (constraint) logic programming (WLP) are the annual meeting of the Society of Logic Programming (GLP e.V.) and bring together researchers interested in logic programming, constraint programming, and related areas like databases, artificial intelligence and operations research. In this decade, previous workshops took place in Dresden (2008), Würzburg (2007), Vienna (2006), Ulm (2005), Potsdam (2004), Dresden (2002), Kiel (2001), and Würzburg (2000). Contributions to workshops deal with all theoretical, experimental, and application aspects of constraint programming (CP) and logic programming (LP), including foundations of constraint/ logic programming. Some of the special topics are constraint solving and optimization, extensions of functional logic programming, deductive databases, data mining, nonmonotonic reasoning, , interaction of CP/LP with other formalisms like agents, XML, JAVA, program analysis, program transformation, program verification, meta programming, parallelism and concurrency, answer set programming, implementation and software techniques (e.g., types, modularity, design patterns), applications (e.g., in production, environment, education, internet), constraint/logic programming for semantic web systems and applications, reasoning on the semantic web, data modelling for the web, semistructured data, and web query languages.
KW  - Logic Programming
KW  - Constraint Solving
KW  - Logics
KW  - Deduction
KW  - Planing
KW  - Optimization
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41401
ER  - 
TY  - CHAP
A1  - Cabalar, Pedro
T1  - Existential quantifiers in the rule body
N2  - In this paper we consider a simple syntactic extension of Answer Set Programming (ASP) for dealing with (nested) existential quantifiers and double negation in the rule bodies, in a close way to the recent proposal RASPL-1. The semantics for this extension just resorts to Equilibrium Logic (or, equivalently, to the General Theory of Stable Models), which provides a logic-programming interpretation for any arbitrary theory in the syntax of Predicate Calculus. We present a translation of this syntactic class into standard logic programs with variables (either disjunctive or normal, depending on the input rule heads), as those allowed by current ASP solvers. The translation relies on the introduction of auxiliary predicates and the main result shows that it preserves strong equivalence modulo the original signature.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41476
ER  - 
TY  - CHAP
A1  - Herre, Heinrich
A1  - Hummel, Axel
T1  - A paraconsistent semantics for generalized logic programs
N2  - We propose a paraconsistent declarative semantics of possibly inconsistent generalized logic programs which allows for arbitrary formulas in the body and in the head of a rule (i.e. does not depend on the presence of any specific connective, such as negation(-as-failure), nor on any specific syntax of rules). For consistent generalized logic programs this semantics coincides with the stable generated models introduced in [HW97], and for normal logic programs it yields the stable models in the sense of [GL88].
KW  - paraconsistency
KW  - generalized logic programs
KW  - multi-valued logic
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41496
ER  - 
TY  - CHAP
A1  - Seipel, Dietmar
T1  - Practical Applications of Extended Deductive Databases in DATALOG*
N2  - A wide range of additional forward chaining applications could be realized with deductive databases, if their rule formalism, their immediate consequence operator, and their fixpoint iteration process would be more flexible. Deductive databases normally represent knowledge using stratified Datalog programs with default negation. But many practical applications of forward chaining require an extensible set of user–defined built–in predicates. Moreover, they often need function symbols for building complex data structures, and the stratified fixpoint iteration has to be extended by aggregation operations. We present an new language Datalog*, which extends Datalog by stratified meta–predicates (including default negation), function symbols, and user–defined built–in predicates, which are implemented and evaluated top–down in Prolog. All predicates are subject to the same backtracking mechanism. The bottom–up fixpoint iteration can aggregate the derived facts after each iteration based on user–defined Prolog predicates.
KW  - deductive databases
KW  - Prolog
KW  - forward / backward chaining
KW  - bottom–up
KW  - top– down
KW  - built–in predicates
KW  - stratification
KW  - function symbols
KW  - XM
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41457
ER  - 
TY  - CHAP
A1  - Brass, Stefan
T1  - Range restriction for general formulas
N2  - Deductive databases need general formulas in rule bodies, not only conjuctions of literals. This is well known since the work of Lloyd and Topor about extended logic programming. Of course, formulas must be restricted in such a way that they can be effectively evaluated in finite time, and produce only a finite number of new tuples (in each iteration of the TP-operator: the fixpoint can still be infinite). It is also necessary to respect binding restrictions of built-in predicates: many of these predicates can be executed only when certain arguments are ground. Whereas for standard logic programming rules, questions of safety, allowedness, and range-restriction are relatively easy and well understood, the situation for general formulas is a bit more complicated. We give a syntactic analysis of formulas that guarantees the necessary properties.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41521
ER  - 
TY  - CHAP
A1  - Piskorski, Jakub
T1  - ExPRESS : extraction pattern recognition engine and specification suite
N2  - The emergence of information extraction (IE) oriented pattern engines has been observed during the last decade. Most of them exploit heavily finite-state devices. This paper introduces ExPRESS – a new extraction pattern engine, whose rules are regular expressions over flat feature structures. The underlying pattern language is a blend of two previously introduced IE oriented pattern formalisms, namely, JAPE, used in the widely known GATE system, and the unificationbased XTDL formalism used in SProUT. A brief and technical overview of ExPRESS, its pattern language and the pool of its native linguistic components is given. Furthermore, the implementation of the grammar interpreter is addressed too.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27227
ER  - 
TY  - CHAP
A1  - Watson, Bruce W.
T1  - Advances in automata implementation techniques (Abstract)
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27094
ER  - 
TY  - CHAP
A1  - Barthélemy, François
T1  - Finite-state compilation of feature structures for two-level morphology
N2  - This paper describes a two-level formalism where feature structures are used in contextual rules. Whereas usual two-level grammars describe rational sets over symbol pairs, this new formalism uses tree structured regular expressions. They allow an explicit and precise definition of the scope of feature structures. A given surface form may be described using several feature structures. Feature unification is expressed in contextual rules using variables, like in a unification grammar. Grammars are compiled in finite state multi-tape transducers.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27120
ER  - 
TY  - CHAP
A1  - Blanc, Olivier
A1  - Constant, Matthieu
A1  - Watrin, Patrick
T1  - Segmentation in super-chunks with a finite-state approach
N2  - Since Harris’ parser in the late 50s, multiword units have been progressively integrated in parsers. Nevertheless, in the most part, they are still restricted to compound words, that are more stable and less numerous. Actually, language is full of semi-fixed expressions that also form basic semantic units: semi-fixed adverbial expressions (e.g. time), collocations. Like compounds, the identification of these structures limits the combinatorial complexity induced by lexical ambiguity. In this paper, we detail an experiment that largely integrates these notions in a finite-state procedure of segmentation into super-chunks, preliminary to a parser.We show that the chunker, developped for French, reaches 92.9% precision and 98.7% recall. Moreover, multiword units realize 36.6% of the attachments within nominal and prepositional phrases.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27133
ER  - 
TY  - CHAP
A1  - Bonfante, Guillaume
A1  - Le Roux, Joseph
T1  - Intersection optimization is NP-complete
N2  - Finite state methods for natural language processing often require the construction and the intersection of several automata. In this paper, we investigate the question of determining the best order in which these intersections should be performed. We take as an example lexical disambiguation in polarity grammars. We show that there is no efficient way to minimize the state complexity of these intersections.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27146
ER  - 
TY  - CHAP
A1  - Daciuk, Jan
T1  - Perfect hashing tree automata
N2  - We present an algorithm that computes a function that assigns consecutive integers to trees recognized by a deterministic, acyclic, finite-state, bottom-up tree automaton. Such function is called minimal perfect hashing. It can be used to identify trees recognized by the automaton. Its value may be seen as an index in some other data structures. We also present an algorithm for inverted hashing.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27163
ER  - 
TY  - CHAP
A1  - Padró, Muntsa
A1  - Padró, Lluís
T1  - ME-CSSR : an extension of CSSR using maximum entropy models
N2  - In this work an extension of CSSR algorithm using Maximum Entropy Models is introduced. Preliminary experiments to perform Named Entity Recognition with this new system are presented.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27210
ER  - 
TY  - CHAP
A1  - Bögel, Tina
A1  - Butt, Miriam
A1  - Hautli, Annette
A1  - Sulger, Sebastian
T1  - Developing a finite-state morphological analyzer for Urdu and Hindi
N2  - We introduce and discuss a number of issues that arise in the process of building a finite-state morphological analyzer for Urdu, in particular issues with potential ambiguity and non-concatenative morphology. Our approach allows for an underlyingly similar treatment of both Urdu and Hindi via a cascade of finite-state transducers that transliterates the very different scripts into a common ASCII transcription system. As this transliteration system is based on the XFST tools that the Urdu/Hindi common morphological analyzer is also implemented in, no compatibility problems arise.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27155
ER  - 
TY  - CHAP
A1  - Yli-Jyrä, Anssi
T1  - Applications of diamonded double negation
N2  - Nested complementation plays an important role in expressing counter- i.e. star-free and first-order definable languages and their hierarchies. In addition, methods that compile phonological rules into finite-state networks use double-nested complementation or “double negation”. This paper reviews how the double-nested complementation extends to a relatively new operation, generalized restriction (GR), coined by the author (Yli-Jyrä and Koskenniemi 2004). This operation encapsulates a double-nested complementation and elimination of a concatenation marker, diamond, whose finite occurrences align concatenations in the arguments of the operation. The paper demonstrates that the GR operation has an interesting potential in expressing regular languages, various kinds of grammars, bimorphisms and relations. This motivates a further study of optimized implementation of the operator.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27109
ER  - 
TY  - CHAP
A1  - Barbaiani, Mădălina
A1  - Cancedda, Nicola
A1  - Dance, Chris
A1  - Fazekas, Szilárd
A1  - Gaál, Tamás
A1  - Gaussier, Éric
T1  - Asymmetric term alignment with selective contiguity constraints by multi-tape automata
N2  - This article describes a HMM-based word-alignment method that can selectively enforce a contiguity constraint. This method has a direct application in the extraction of a bilingual terminological lexicon from a parallel corpus, but can also be used as a preliminary step for the extraction of phrase pairs in a Phrase-Based Statistical Machine Translation system. Contiguous source words composing terms are aligned to contiguous target language words. The HMM is transformed into a Weighted Finite State Transducer (WFST) and contiguity constraints are enforced by specific multi-tape WFSTs. The proposed method is especially suited when basic linguistic resources (morphological analyzer, part-of-speech taggers and term extractors) are available for the source language only.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27115
ER  - 
TY  - CHAP
A1  - Karttunen, Lauri
T1  - New features in PARC finite state toolkits (Abstract)
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27085
ER  - 
TY  - CHAP
A1  - Yli-Jyrä, Anssi
T1  - Transducers from parallel replace rules and modes with generalized lenient composition
N2  - Generalized Two-Level Grammar (GTWOL) provides a new method for compilation of parallel replacement rules into transducers. The current paper identifies the role of generalized lenient composition (GLC) in this method. Thanks to the GLC operation, the compilation method becomes bipartite and easily extendible to capture various application modes. In the light of three notions of obligatoriness, a modification to the compilation method is proposed. We argue that the bipartite design makes implementation of parallel obligatoriness, directionality, length and rank based application modes extremely easy, which is the main result of the paper.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27246
ER  - 
TY  - CHAP
A1  - Saléschus, Dirk
T1  - On resolving long distance dependencies in Russian verbs
N2  - Morphological analyses based on word syntax approaches can encounter difficulties with long distance dependencies. The reason is that in some cases an affix has to have access to the inner structure of the form with which it combines. One solution is the percolation of features from ther inner morphemes to the outer morphemes with some process of feature unification. However, the obstacle of percolation constraints or stipulated features has lead some linguists to argue in favour of other frameworks such as, e.g., realizational morphology or parallel approaches like optimality theory. This paper proposes a linguistic analysis of two long distance dependencies in the morphology of Russian verbs, namely secondary imperfectivization and deverbal nominalization.We show how these processes can be reanalysed as local dependencies. Although finitestate frameworks are not bound by such linguistically motivated considerations, we present an implementation of our analysis as proposed in [1] that does not complicate the grammar or enlarge the network unproportionally.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27235
ER  - 
TY  - CHAP
A1  - Ilarraza, Arantza Díaz de
A1  - Gojenola, Koldo
A1  - Oronoz, Maite
A1  - Otaegi, Maialen
A1  - Alegria, Iñaki
T1  - Syntactic error detection and correction in date expressions using finite-state transducers
N2  - This paper presents a system for the detection and correction of syntactic errors. It combines a robust morphosyntactic analyser and two groups of finite-state transducers specified using the Xerox Finite State Tool (xfst). One of the groups is used for the description of syntactic error patterns while the second one is used for the correction of the detected errors. The system has been tested on a corpus of real texts, containing both correct and incorrect sentences, with good results.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27180
ER  - 
TY  - CHAP
A1  - Fernando, Tim
T1  - Temporal propositions as regular languages
N2  - Temporal propositions are mapped to sets of strings that witness (in a precise sense) the propositions over discrete linear Kripke frames. The strings are collected into regular languages to ensure the decidability of entailments given by inclusions between languages. (Various notions of bounded entailment are shown to be expressible as language inclusions.) The languages unwind computations implicit in the logical (and temporal) connectives via a system of finite-state constraints adapted from finite-state morphology. Applications to Hybrid Logic and non-monotonic inertial reasoning are briefly considered.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27194
ER  - 
TY  - CHAP
A1  - Didakowski, Jörg
T1  - SynCoP : combining syntactic tagging with chunking using weighted finite state transducers
N2  - This paper describes the key aspects of the system SynCoP (Syntactic Constraint Parser) developed at the Berlin-Brandenburgische Akademie der Wissenschaften. The parser allows to combine syntactic tagging and chunking by means of constraint grammar using weighted finite state transducers (WFST). Chunks are interpreted as local dependency structures within syntactic tagging. The linguistic theories are formulated by criteria which are formalized by a semiring; these criteria allow structural preferences and gradual grammaticality. The parser is essentially a cascade of WFSTs. To find the most likely syntactic readings a best-path search is used.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27172
ER  - 
TY  - CHAP
A1  - Zarrieß, Sina
A1  - Seeker, Wolfgang
T1  - Finite-state rule deduction for parsing non-constituent coordination
N2  - In this paper, we present a finite-state approach to constituency and therewith an analysis of coordination phenomena involving so-called non-constituents. We show that non-constituents can be seen as parts of fully-fledged constituents and therefore be coordinated in the same way. We have implemented an algorithm based on finite state automata that generates an LFG grammar assigning valid analyses to non-constituent coordination structures in the German language.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27254
ER  - 
TY  - CHAP
A1  - González, Jorge
A1  - Casacuberta, Francisco
T1  - Phrase-based finite state models
N2  - In the last years, statistical machine translation has already demonstrated its usefulness within a wide variety of translation applications. In this line, phrase-based alignment models have become the reference to follow in order to build competitive systems. Finite state models are always an interesting framework because there are well-known efficient algorithms for their representation and manipulation. This document is a contribution to the evolution of finite state models towards a phrase-based approach. The inference of stochastic transducers that are based on bilingual phrases is carefully analysed from a finite state point of view. Indeed, the algorithmic phenomena that have to be taken into account in order to deal with such phrase-based finite state models when in decoding time are also in-depth detailed.
Y1  - 2008
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27209
ER  - 
TY  - CHAP
A1  - Reimer, O.
A1  - Aharonian, Felix A.
A1  - Hinton, J.
A1  - Hofmann, W.
A1  - Hoppe, S.
A1  - Raue, M.
A1  - Reimer, A.
T1  - VHE gamma-rays from Westerlund 2 and implications for the inferred energetics
N2  - The H.E.S.S. collaboration recently reported the discovery of VHE γ-ray emission coincident with the young stellar cluster Westerlund 2. This system is known to host a population of hot, massive stars, and, most particularly, the WR binary WR 20a. Particle acceleration to TeV energies in Westerlund 2 can be accomplished in several alternative scenarios, therefore we only discuss energetic constraints based on the total available kinetic energy in the system, the actual mass loss rates of respective cluster members, and implied gamma-ray production from processes such as inverse Compton scattering or neutral pion decay. From the inferred gammaray luminosity of the order of 1035erg/s, implications for the efficiency of converting available kinetic energy into non-thermal radiation associated with stellar winds in the Westerlund 2 cluster are discussed under consideration of either the presence or absence of wind clumping.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18172
ER  - 
TY  - CHAP
A1  - Hirschi, Raphael
T1  - The impact of reduced mass loss rates on the evolution of massive stars
N2  - Mass loss is a very important aspect of the life of massive stars. After briefly reviewing its importance, we discuss the impact of the recently proposed downward revision of mass loss rates due to clumping (difficulty to form Wolf-Rayet stars and production of critically rotating stars). Although a small reduction might be allowed, large reduction factors around ten are disfavoured. We then discuss the possibility of significant mass loss at very low metallicity due to stars reaching break-up velocities and especially due to the metal enrichment of the surface of the star via rotational and convective mixing. This significant mass loss may help the first very massive stars avoid the fate of pair-creation supernova, the chemical signature of which is not observed in extremely metal poor stars. The chemical composition of the very low metallicity winds is very similar to that of the most metal poor star known to date, HE1327-2326 and offer an interesting explanation for the origin of the metals in this star. We also discuss the importance of mass loss in the context of long and soft gamma-ray bursts and pair-creation supernovae. Finally, we would like to stress that mass loss in cooler parts of the HR-diagram (luminous blue variable and yellow and red supergiant stages) are much more uncertain than in the hot part. More work needs to be done in these areas to better constrain the evolution of the most massive stars.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17616
ER  - 
TY  - CHAP
A1  - Fullerton, A. W.
A1  - Massa, D. L.
A1  - Prinja, R. K.
T1  - Revised mass-loss rates for O stars from the Pv resonance line
N2  - The P v λλ1118, 1128 resonance doublet is an extraordinarily useful diagnostic of O-star winds, because it bypasses the traditional problems associated with determining mass-loss rates from UV resonance lines. We discuss critically the assumptions and uncertainties involved with using P v to diagnose mass-loss rates, and conclude that the large discrepancies between massloss rates determined from P v and the rates determined from “density squared” emission processes pose a significant challenge to the “standard model” of hot-star winds. The disparate measurements can be reconciled if the winds of O-type stars are strongly clumped on small spatial scales, which in turn implies that mass-loss rates based on Hα or radio emission are too large by up to an order of magnitude.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17647
ER  - 
TY  - CHAP
A1  - Bouret, J.-C.
A1  - Lanz, T.
A1  - Hillier, D. J.
A1  - Foellmi, C.
T1  - Clumping in O-type Supergiants
N2  - We have analyzed the spectra of seven Galactic O4 supergiants, with the NLTE wind code CMFGEN. For all stars, we have found that clumped wind models match well lines from different species spanning a wavelength range from FUV to optical, and remain consistent with Hα data. We have achieved an excellent match of the P V λλ1118, 1128 resonance doublet and N IV λ1718, as well as He II λ4686 suggesting that our physical description of clumping is adequate. We find very small volume filling factors and that clumping starts deep in the wind, near the sonic point. The most crucial consequence of our analysis is that the mass loss rates of O stars need to be revised downward significantly, by a factor of 3 and more compared to those obtained from smooth-wind models.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17662
ER  - 
TY  - CHAP
A1  - Gull, T. R.
T1  - Eta Carinae viewed from different vantages
N2  - The spatially-resolved winds of the massive binary, Eta Carinae, extend an arcsecond on the sky, well beyond the 10 to 20 milliarcsecond binary orbital dimension. Stellar wind line profiles, observed at very different angular resolutions of VLTI/AMBER, HST/STIS and VLT/UVES, provide spatial information on the extended wind interaction structure as it changes with orbital phase. These same wind lines, observable in the starlight scattered off the foreground lobe of the dusty Homunculus, provide time-variant line profiles viewed from significantly different angles. Comparisons of direct and scattered wind profiles observed in the same epoch and at different orbital phases provide insight on the extended wind structure and promise the potential for three-dimensional imaging of the outer wind structures. Massive, long-lasting clumps, including the nebularWeigelt blobs, originated during the two historical ejection events. Wind interactions with these clumps are quite noticeable in spatially-resolved spectroscopy. As the 2009.0 minimum approaches, analysis of existing spectra and 3-D modeling are providing bases for key observations to gain further understanding of this complex massive binary.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18200
ER  - 
TY  - CHAP
A1  - Reimer, A.
T1  - Clumping effects on non-thermal particle spectra in massive star systems
N2  - Observational evidence exists that winds of massive stars are clumped. Many massive star systems are known as non-thermal particle production sites, as indicated by their synchrotron emission in the radio band. As a consequence they are also considered as candidate sites for non-thermal high-energy photon production up to gamma-ray energies. The present work considers the effects of wind clumpiness expected on the emitting relativistic particle spectrum in colliding wind systems, built up from the pool of thermal wind particles through diffusive particle acceleration, and taking into account inverse Compton and synchrotron losses. In comparison to a homogeneous wind, a clumpy wind causes flux variations of the emitting particle spectrum when the clump enters the wind collision region. It is found that the spectral features associated with this variability moves temporally from low to high energy bands with the time shift between any two spectral bands being dependent on clump size, filling factor, and the energy-dependence of particle energy gains and losses.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18246
ER  - 
TY  - CHAP
A1  - Schnurr, O.
A1  - Crowther, P. A.
T1  - Mid-IR observations of WC stars, and the connection to wind clumping
N2  - We present preliminary results of a tailored atmosphere analysis of six Galactic WC stars using UV, optical, and mid-infrared Spitzer IRS data. With these data, we are able to sample regions from 10 to 10³ stellar radii, thus to determine wind clumping in different parts of the wind. Ultimately, derived wind parameters will be used to accuratelymeasure neon abundances, and to so test predicted nuclear-reaction rates.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17884
ER  - 
TY  - CHAP
A1  - Vink, J. S.
A1  - Benaglia, P.
A1  - Davies, B.
A1  - de Koter, A.
A1  - Oudmaijer, R. D.
T1  - Advances in mass-loss predictions
N2  - We present the results of Monte Carlo mass-loss predictions for massive stars covering a wide range of stellar parameters. We critically test our predictions against a range of observed massloss rates – in light of the recent discussions on wind clumping. We also present a model to compute the clumping-induced polarimetric variability of hot stars and we compare this with observations of Luminous Blue Variables, for which polarimetric variability is larger than for O and Wolf-Rayet stars. Luminous Blue Variables comprise an ideal testbed for studies of wind clumping and wind geometry, as well as for wind strength calculations, and we propose they may be direct supernova progenitors.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17948
ER  - 
TY  - CHAP
A1  - Moffat, Anthony F. J.
A1  - Hillier, D. J.
A1  - Hamann, Wolf-Rainer
A1  - Owocki, S. P.
T1  - General Discussion
N2  - Clumping in hot-star winds : proceedings of an international workshop held in Potsdam, Germany, 18. - 22. June 2007
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17953
ER  - 
TY  - CHAP
A1  - Sonneborn, G.
T1  - Imaging and spectroscopy with the James Webb Space Telescope
N2  - The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2013. JWST will find the first stars and galaxies that formed in the early universe, connecting the Big Bang to our own Milky Way galaxy. JWST will peer through dusty clouds to see stars forming planetary systems, connecting the MilkyWay to our own Solar System. JWST’s instruments are designed to work primarily in the infrared range of 1 - 28 μm, with some capability in the visible range. JWST will have a large mirror, 6.5 m in diameter, and will be diffraction-limited at 2 μm (0.1 arcsec resolution). JWST will be placed in an L2 orbit about 1.5 million km from the Earth. The instruments will provide imaging, coronography, and multi-object and integral-field spectroscopy across the 1 - 28 μm wavelength range. The breakthrough capabilities of JWST will enable new studies of massive star winds from the Milky Way to the early universe.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17983
ER  - 
TY  - CHAP
A1  - Owocki, S. P.
T1  - Dynamical simulation of the “velocity-porosity” reduction in observed strength of stellar wind lines
N2  - I use dynamical simulations of the line-driven instability to examine the potential role of the resulting flow structure in reducing the observed strength of wind absorption lines. Instead of the porosity length formalism used to model effects on continuum absorption, I suggest reductions in line strength can be better characterized in terms of a velocity clumping factor that is insensitive to spatial scales. Examples of dynamic spectra computed directly from instability simulations do exhibit a net reduction in absorption, but only at a modest 10-20% level that is well short of the ca. factor 10 required by recent analyses of PV lines.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17992
ER  - 
TY  - CHAP
A1  - Blomme, R.
T1  - Corotating Interaction Regions and clumping
N2  - We present hydrodynamical models for Corotating Interaction Regions, which were used by Lobel (2007) to model the Discrete Absorption Components in HD 64760. We also discuss our failure to model the rotational modulations seen in the same star.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18100
ER  - 
TY  - CHAP
A1  - Kholtygin, A. F.
T1  - Wavelets for looking for clumping in the wind of OB stars
N2  - Clumping in hot-star winds : proceedings of an international workshop held in Potsdam, Germany, 18. - 22. June 2007
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17796
ER  - 
TY  - CHAP
A1  - Urbaneja, M. A.
A1  - Kudritzki, R.-P.
A1  - Puls, Joachim
T1  - Clumping in the winds of O-type CSPNs
N2  - Recent studies of massive O-type stars present clear evidences of inhomogeneous and clumped winds. O-type (H-rich) central stars of planetary nebulae (CSPNs) are in some ways the low mass–low luminosity analogous of those massive stars. In this contribution, we present preliminary results of our on-going multi-wavelength (FUV, UV and optical) study of the winds of Galactic CSPNs. Particular emphasis will be given to the clumping factors derived by means of optical lines (Hα and Heii 4686) and “classic” FUV (and UV) lines.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17801
ER  - 
TY  - CHAP
A1  - de Koter, A.
A1  - Vink, J. S.
A1  - Muijres, L.
T1  - Constraints on wind clumping from the empirical mass-loss vs. metallicity relation for early-type stars
N2  - We present the latest results on the observational dependence of the mass-loss rate in stellar winds of O and early-B stars on the metal content of their atmospheres, and compare these with predictions. Absolute empirical rates for the mass loss of stars brighter than 10$^{5.2} L_{\odot}$, based on H$\alpha$ and ultraviolet (UV) wind lines, are found to be about a factor of two higher than predictions. If this difference is attributed to inhomogeneities in the wind this would imply that luminous O and early-B stars have clumping factors in their H$\alpha$ and UV line forming regime of about a factor of 3--5. The investigated stars cover a metallicity range $Z$ from 0.2 to 1 $Z_{\odot}$. We find a hint towards smaller clumping factors for lower $Z$. The derived clumping factors, however, presuppose that clumping does not impact the predictions of the mass-loss rate. We discuss this assumption and explain how we intend to investigate its validity in more detail.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17736
ER  -