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@INPROCEEDINGS{DvorakSW12,
  author = {Wolfgang Dvo\v{r}\'ak and Stefan Szeider and Stefan Woltran},
  title = {Abstract Argumentation via Monadic Second Order Logic},
  booktitle = {Scalable Uncertainty Management - 6th International Conference, SUM
	2012, Marburg, Germany, September 17-19, 2012. Proceedings},
  year = {2012},
  editor = {Eyke H{\"u}llermeier and Sebastian Link and Thomas Fober and Bernhard
	Seeger},
  volume = {7520},
  series = {Lecture Notes in Computer Science},
  pages = {85-98},
  publisher = {Springer},
  crossref = {DBLP:conf/sum/2012},
  ee = {http://dx.doi.org/10.1007/978-3-642-33362-0_7},
  isbn = {978-3-642-33361-3}
}

@INPROCEEDINGS{BaumannBDW12,
  author = {Ringo Baumann and Gerhard Brewka and Wolfgang Dvo\v{r}\'ak and Stefan
	Woltran},
  title = {Parameterized Splitting: A Simple Modification-Based Approach},
  booktitle = {Correct Reasoning - Essays on Logic-Based AI in Honour of Vladimir
	Lifschitz},
  year = {2012},
  editor = {Esra Erdem and Joohyung Lee and Yuliya Lierler and David Pearce},
  volume = {7265},
  series = {Lecture Notes in Computer Science},
  pages = {57-71},
  publisher = {Springer},
  ee = {http://dx.doi.org/10.1007/978-3-642-30743-0_5},
  isbn = {978-3-642-30742-3}
}

@INPROCEEDINGS{CharwatD12,
  author = {G{\"u}nther Charwat and Wolfgang Dvo\v{r}\'ak},
  title = {dynPARTIX 2.0 - Dynamic Programming Argumentation Reasoning Tool},
  booktitle = {Computational Models of Argument - Proceedings of COMMA 2012, Vienna,
	Austria, September 10-12, 2012},
  year = {2012},
  editor = {Bart Verheij and Stefan Szeider and Stefan Woltran},
  volume = {245},
  series = {Frontiers in Artificial Intelligence and Applications},
  pages = {507-508},
  publisher = {IOS Press},
  ee = {http://dx.doi.org/10.3233/978-1-61499-111-3-507},
  isbn = {978-1-61499-110-6}
}

@INPROCEEDINGS{DunneDLW13,
  author = {Paul E. Dunne and Wolfgang Dvo\v{r}\'ak and Thomas Linsbichler and
	and Stefan Woltran},
  title = {Characteristics of Multiple Viewpoints in Abstract Argumentation},
  booktitle = {4th Workshop on Dynamics of Knowledge and Belief (},
  year = {2013}
}

@ARTICLE{DunneDW13,
  author = {Paul E. Dunne and Wolfgang Dvo\v{r}\'ak and Stefan Woltran},
  title = {Parametric properties of ideal semantics },
  journal = {Artificial Intelligence },
  year = {2013},
  volume = {202},
  pages = {1 - 28},
  number = {0},
  abstract = {Abstract The concept of “ideal semantics” has been promoted as an
	alternative basis for skeptical reasoning within abstract argumentation
	settings. Informally, ideal acceptance not only requires an argument
	to be skeptically accepted in the traditional sense but further insists
	that the argument is in an admissible set all of whose arguments
	are also skeptically accepted. The original proposal was couched
	in terms of the so-called preferred semantics for abstract argumentation.
	We argue, in this paper, that the notion of “ideal acceptability”
	is applicable to arbitrary semantics and justify this claim by showing
	that standard properties of classical ideal semantics, e.g. unique
	status, continue to hold in any “reasonable” extension-based semantics.
	We categorise the relationship between the divers concepts of “ideal
	extension w.r.t. semantics σ” that arise and we present a comprehensive
	analysis of algorithmic and complexity-theoretic issues. In addition
	we offer further support for the view that “ideal semantics” ought
	to be seen as a generic property by presenting and analysing the
	forms that these might take within value-based argumentation frameworks.
	},
  doi = {http://dx.doi.org/10.1016/j.artint.2013.06.004},
  issn = {0004-3702},
  url = {http://www.sciencedirect.com/science/article/pii/S0004370213000593}
}

@INPROCEEDINGS{Dvorak12b,
  author = {Wolfgang Dvo\v{r}\'ak},
  title = {On the Complexity of Computing the Justification Status of an Argument},
  booktitle = {Theory and Applications of Formal Argumentation - First International
	Workshop, TAFA 2011. Barcelona, Spain, July 16-17, 2011, Revised
	Selected Papers},
  year = {2012},
  editor = {Sanjay Modgil and Nir Oren and Francesca Toni},
  volume = {7132},
  series = {Lecture Notes in Computer Science},
  pages = {32-49},
  publisher = {Springer},
  abstract = {We address the problem of determining the acceptance status of an
	argument w.r.t. labeling-based semantics. Wu and Caminada recently
	proposed a labeling-based justification status of arguments to distinguish
	different levels of acceptability for arguments. We generalize their
	approach, which was originally restricted to complete semantics,
	to arbitrary argumentation semantics and provide a comprehensive
	study of the computational properties.},
  ee = {http://dx.doi.org/10.1007/978-3-642-29184-5_3},
  isbn = {978-3-642-29183-8}
}

@TECHREPORT{Dvorak12,
  author = {Wolfgang Dvo\v{r}\'ak},
  title = {Technical Note: Exploring {$\Sigma^P_2$ / $\Pi^P_2$} -hardness for
	Argumentation Problems with fixed distance to tractable classes},
  institution = {CoRR},
  year = {2012},
  abstract = {Abstract: We study the complexity of reasoning in abstracts argumentation
	frameworks close to graph classes that allow for efficient reasoning
	methods, i.e.\ to one of the classes of acyclic, noeven, biparite
	and symmetric AFs. In this work we show that certain reasoning problems
	on the second level of the polynomial hierarchy still maintain their
	full complexity when restricted to instances of fixed distance to
	one of the above graph classes.},
  ee = {http://arxiv.org/abs/1201.0478},
  journal = {CoRR},
  volume = {abs/1201.0478}
}

@PHDTHESIS{Dvorak12c,
  author = {Wolfgang Dvo\v{r}\'ak},
  title = {Computational Aspects of Abstract Argumentation},
  school = {Technische Universität Wien},
  year = {2012},
  ee = {http://permalink.obvsg.at/AC07812708},
  pages = {I-X, 1-143}
}

@INPROCEEDINGS{DvorakDW11,
  author = {Wolfgang Dvo\v{r}\'ak and Paul E. Dunne and Stefan Woltran},
  title = {Parametric Properties of Ideal Semantics},
  booktitle = {IJCAI 2011, Proceedings of the 22nd International Joint Conference
	on Artificial Intelligence, Barcelona, Catalonia, Spain, July 16-22,
	2011},
  year = {2011},
  editor = {Toby Walsh},
  pages = {851-856},
  publisher = {IJCAI/AAAI},
  abstract = {The concept of ``ideal semantics'' has been promoted as an alternative
	basis for skeptical reasoning within abstract argumentation settings.
	Informally, ideal acceptance not only requires an argument to be
	skeptically accepted in the traditional sense but further insists
	that the argument is in an admissible set all of whose arguments
	are also skeptically accepted. The original proposal was couched
	in terms of the so-called preferred semantics for abstract argumentation.
	We argue, in this paper, that the notion of ``ideal acceptability''
	is applicable to arbitrary semantics and justify this claim by showing
	that standard properties of classical ideal semantics, e.g. unique
	status, continue to hold in any ``reasonable'' extension-based semantics.
	We categorise the relationship between the divers concepts of ``ideal
	extension w.r.t. semantics \sigma'' that arise and we present a comprehensive
	analysis of algorithmic and complexity-theoretic issues.},
  bibsource = {DBLP, http://dblp.uni-trier.de},
  ee = {http://ijcai.org/papers11/Papers/IJCAI11-148.pdf},
  isbn = {978-1-57735-516-8}
}

@INPROCEEDINGS{DvorakG12b,
  author = {Wolfgang Dvo\v{r}\'ak and Sarah Alice Gaggl},
  title = {Computational Aspects of cf2 and stage2 Argumentation Semantics},
  booktitle = {Computational Models of Argument - Proceedings of COMMA 2012, Vienna,
	Austria, September 10-12, 2012},
  year = {2012},
  editor = {Bart Verheij and Stefan Szeider and Stefan Woltran},
  volume = {245},
  series = {Frontiers in Artificial Intelligence and Applications},
  pages = {273-284},
  publisher = {IOS Press},
  ee = {http://dx.doi.org/10.3233/978-1-61499-111-3-273},
  isbn = {978-1-61499-110-6}
}

@TECHREPORT{dbai-tr-2012-78,
  author = {Wolfgang Dvo\v{r}\'ak and Sarah Alice Gaggl},
  title = {Incorporating Stage Semantics in the SCC-recursive Schema for Argumentation
	Semantics.},
  institution = {Technische Universität Wien},
  year = {2012},
  type = {Technical Report},
  number = {DBAI-TR-2011-78},
  abstract = {Recently, the stage and cf2 semantics for abstract argumentation attracted
	specific attention. By distancing from the notion of defense, they
	are capable to select arguments outof odd-length cycles. Furthermore,
	the maximality criterion of naive sets ensures reasonablesolutions.
	The SCC-recursive schema, where the cf2 semantics is defined in,
	guarantees that some specific evaluation criteria, like directionality,
	weak- and CF-reinstatement, are fulfilled. Beside several desirable
	properties, both stage and cf2 semantics still have some drawbacks.
	The stage semantics does not satisfy the above mentioned evaluation
	criteria, whereas cf2 semantics produces some questionable results
	on frameworks with cycles of length >= 6. That?s why we suggest to
	combine stage semantics with the SCC-recursive schema of cf2 semantics.
	The resulting stage2 semantics overcomes the problems regarding cf2
	semantics and still fulfills the mentioned evaluation criteria. Furthermore,
	we analyze redundant patterns for stage2 semantics, and we provide
	a complexity analysis of the associated reasoning problems.},
  pdf = {http://www.dbai.tuwien.ac.at/research/report/dbai-tr-2012-78.pdf}
}

@INPROCEEDINGS{DvorakG12,
  author = {Wolfgang Dvo\v{r}\'ak and Sarah Alice Gaggl},
  title = {Incorporating Stage Semantics in the SCC-recursive Schema for Argumentation
	Semantics.},
  booktitle = {Proceedings of the 14th International Workshop on Non-Monotonic Reasoning},
  year = {2012}
}

@INCOLLECTION{DvorakGSW13,
  author = {Wolfgang Dvo\v{r}\'ak and Sarah Alice Gaggl and Stefan Szeider and
	Stefan Woltran},
  title = {Benchmark Libraries for Argumentation},
  booktitle = {Agreement Technologies},
  publisher = {Springer},
  year = {2013},
  editor = {Sascha Ossowski},
  volume = {8},
  series = {LGTS},
  chapter = {The Added Value of Argumentation},
  pages = {389--393}
}

@TECHREPORT{dbai-tr-2011-70,
  author = {Wolfgang Dvo\v{r}\'ak and Sarah Alice Gaggl and Johannes Wallner
	and Stefan Woltran},
  title = {Making Use of Advances in Answer-Set Programming for Abstract Argumentation
	Systems.},
  institution = {Technische Universität Wien},
  year = {2011},
  type = {Technical Report},
  number = {DBAI-TR-2011-70},
  abstract = {Dung's famous abstract argumentation frameworks represent the core
	formalism for many problems and applications in the field of argumentation
	which significantly evolved within the last decade.
	
	Recent work in the field has thus focused on implementations for these
	frameworks, whereby one of the main approaches is to use Answer-Set
	Programming (ASP). While some of the argumentation semantics can
	be nicely expressed within the ASP language, others required rather
	cumbersome encoding techniques. 
	
	Recent advances in ASP systems, in particular, the metasp optimization
	frontend for the ASP-package gringo/claspD provides direct commands
	to filter answer-sets satisfying certain subset-minimality (or -maximality)
	constraints. This allows for much simpler encodings compared to the
	ones in standard ASP language.
	
	In this paper, we experimentally compare the original encodings (for
	the argumentation semantics based on preferred, semi-stable, and
	respectively, stage extensions) with new metasp encodings, thus evaluating
	the efficiency of the novel metasp technique.
	
	Moreover, we provide novel encodings for the recently introduced resolution-based
	grounded semantics. Our experimental results indicate that the metasp
	approach works well in those cases where the complexity of the encoded
	problem is adequately mirrored within the metasp approach.},
  url = {http://www.dbai.tuwien.ac.at/research/report/dbai-tr-2011-70.pdf}
}

@TECHREPORT{DvorakGWW11,
  author = {Wolfgang Dvo\v{r}\'ak and Sarah Alice Gaggl and Johannes Peter Wallner
	and Stefan Woltran},
  title = {Making Use of Advances in Answer-Set Programming for Abstract Argumentation
	Systems},
  institution = {CoRR},
  year = {2011},
  note = {In Proceedings of the 19th International Conference on Applications
	of Declarative Programming and Knowledge Management (INAP 2011)},
  abstract = {Dung's famous abstract argumentation frameworks represent the core
	formalism for many problems and applications in the field of argumentation
	which significantly evolved within the last decade. Recent work in
	the field has thus focused on implementations for these frameworks,
	whereby one of the main approaches is to use Answer-Set Programming
	(ASP). While some of the argumentation semantics can be nicely expressed
	within the ASP language, others required rather cumbersome encoding
	techniques. Recent advances in ASP systems, in particular, the metasp
	optimization frontend for the ASP-package gringo/claspD provides
	direct commands to filter answer sets satisfying certain subset-minimality
	(or -maximality) constraints. This allows for much simpler encodings
	compared to the ones in standard ASP language. In this paper, we
	experimentally compare the original encodings (for the argumentation
	semantics based on preferred, semi-stable, and respectively, stage
	extensions) with new metasp encodings. Moreover, we provide novel
	encodings for the recently introduced resolution-based grounded semantics.
	Our experimental results indicate that the metasp approach works
	well in those cases where the complexity of the encoded problem is
	adequately mirrored within the metasp approach.},
  bibsource = {DBLP, http://dblp.uni-trier.de},
  ee = {http://arxiv.org/abs/1108.4942},
  journal = {CoRR},
  volume = {abs/1108.4942}
}

@TECHREPORT{dbai-tr-2009-64,
  author = {Wolfgang Dvo\v{r}\'ak and Georg Gottlob and Reinhard Pichler and
	Stefan Woltran},
  title = {Alternation as a Programming Paradigm},
  institution = {Technische Universit\"at Wien, Database and Artificial Intelligence
	Group},
  year = {2009},
  number = {DBAI-TR-2009-64},
  abstract = {In this work, we show how the expressive power of an imperative programming
	language can be augmented by integrating alternation into it. In
	particular, we present Alter-Java - an extension of Java by language
	constructs to express alternation, i.e., a sequence of "there exists"
	and "for all" statements. Indeed, many practical problems have a
	very naturaland succinct description in terms of alternation. Two-player
	games are obvious representatives of this species. But alternation
	is by no means limited to games. Also many problems with a procedural
	description of the solutions have a very compact declarative descriptionvia
	alternation, among them the evaluation of logic programs. Alternation
	is commonly applied to complexity theoretical studies where it has
	proved very useful in various complexity classifications. In this
	work, we demonstrate that alternation is also a practically relevant
	programming paradigm which nicely fits into general purpose programming
	languages. In order to guarantee an efficient execution of such programs,
	we have introduced several optimizations. We also report on experiments
	with our implementation of Alter-Java. The results thus obtained
	illustrate that our alternation framework leads to competitive running
	times while the code to be written is significantly shorter than
	without this new language feature.},
  url = {http://www.dbai.tuwien.ac.at/research/report/dbai-tr-2009-64.pdf}
}

@INPROCEEDINGS{DvorakGPW09a,
  author = {Wolfgang Dvo\v{r}\'ak and Georg Gottlob and Reinhard Pichler and
	Stefan Woltran},
  title = {Alternation as a programming paradigm},
  booktitle = {PPDP '09: Proceedings of the 11th ACM SIGPLAN conference on Principles
	and practice of declarative programming},
  year = {2009},
  pages = {61--72},
  address = {New York, NY, USA},
  publisher = {ACM},
  abstract = {Alternation is a common tool in complexity theory, where it has been
	used to prove various complexity classifications. In this work, we
	show that it can also be used to enhance the expressive power of
	the imperative part of a programming language. In particular, we
	present Alter-Java an extension of Java by language constructs to
	express alternation, i.e., a sequence of "there exists" and "for
	all" statements. Moreover, we show that many practical problems have
	a very natural and succinct description in terms of alternation.
	In order to guarantee an efficient execution of such programs, we
	have introduced several optimizations. We also report on experiments
	with our implementation of Alter-Java. The results thus obtained
	illustrate that our alternation framework leads to competitive running
	times while the code to be written is significantly shorter than
	without this new language feature.},
  doi = {http://doi.acm.org/10.1145/1599410.1599419},
  isbn = {978-1-60558-568-0},
  location = {Coimbra, Portugal}
}

@INPROCEEDINGS{DvorakHW13,
  author = {Wolfgang Dvo\v{r}\'ak and Monika Henzinger and David P. Williamson},
  title = {Maximizing a Submodular Function with Viability Constraints},
  booktitle = {Algorithms - ESA 2013 - 21st Annual European Symposium, Sophia Antipolis,
	France, September 2-4, 2013. Proceedings},
  year = {2013},
  editor = {Hans L. Bodlaender and Giuseppe F. Italiano},
  volume = {8125},
  series = {Lecture Notes in Computer Science},
  pages = {409-420},
  publisher = {Springer},
  ee = {http://dx.doi.org/10.1007/978-3-642-40450-4_35},
  isbn = {978-3-642-40449-8}
}

@INPROCEEDINGS{DvorakJWW12,
  author = {Wolfgang Dvo\v{r}\'ak and Matti J{\"a}rvisalo and Johannes Peter
	Wallner and Stefan Woltran},
  title = {Complexity-Sensitive Decision Procedures for Abstract Argumentation},
  booktitle = {Principles of Knowledge Representation and Reasoning: Proceedings
	of the Thirteenth International Conference, KR 2012, Rome, Italy,
	June 10-14, 2012},
  year = {2012},
  editor = {Gerhard Brewka and Thomas Eiter and Sheila A. McIlraith},
  pages = {54-64},
  publisher = {AAAI Press},
  abstract = {Abstract argumentation frameworks (AFs) provide the basis for various
	reasoning problems in the areas of Knowledge Representation and Artificial
	Intelligence. Efficient evaluation of AFs has thus been identified
	as an important research challenge. So far, implemented systems for
	evaluating AFs have either followed a straight-forward reduction-based
	approach or been limited to certain tractable classes of AFs. In
	this work, we present a generic approach for reasoning over AFs,
	based on the novel concept of complexity-sensitivity. Establishing
	the theoretical foundations of this approach, we derive several new
	complexity results for preferred, semi-stable and stage semantics
	which complement the current complexity landscape for abstract argumentation,
	providing further understanding on the sources of intractability
	of AF reasoning problems. The introduced generic framework exploits
	decision procedures for problems of lower complexity whenever possible.
	This allows, in particular, instantiations of the generic framework
	via harnessing in an iterative way current sophisticated Boolean
	satisfiability (SAT) solver technology for solving the considered
	AF reasoning problems. First experimental results show that the SAT-based
	instantiation of our novel approach outperforms existing systems.},
  ee = {http://www.aaai.org/ocs/index.php/KR/KR12/paper/view/4508},
  isbn = {978-1-57735-560-1}
}

@ARTICLE{DvorakJWW13,
  author = {Wolfgang Dvo\v{r}\'ak and Matti Järvisalo and Johannes Peter Wallner
	and Stefan Woltran},
  title = {Complexity-sensitive decision procedures for abstract argumentation
	},
  journal = {Artificial Intelligence },
  year = {2014},
  volume = {206},
  pages = {53 - 78},
  number = {0},
  abstract = {Abstract Abstract argumentation frameworks (AFs) provide the basis
	for various reasoning problems in the area of Artificial Intelligence.
	Efficient evaluation of \{AFs\} has thus been identified as an important
	research challenge. So far, implemented systems for evaluating \{AFs\}
	have either followed a straight-forward reduction-based approach
	or been limited to certain tractable classes of AFs. In this work,
	we present a generic approach for reasoning over AFs, based on the
	novel concept of complexity-sensitivity. Establishing the theoretical
	foundations of this approach, we derive several new complexity results
	for preferred, semi-stable and stage semantics which complement the
	current complexity landscape for abstract argumentation, providing
	further understanding on the sources of intractability of \{AF\}
	reasoning problems. The introduced generic framework exploits decision
	procedures for problems of lower complexity whenever possible. This
	allows, in particular, instantiations of the generic framework via
	harnessing in an iterative way current sophisticated Boolean satisfiability
	(SAT) solver technology for solving the considered \{AF\} reasoning
	problems. First experimental results show that the SAT-based instantiation
	of our novel approach outperforms existing systems. },
  doi = {http://dx.doi.org/10.1016/j.artint.2013.10.001},
  issn = {0004-3702}
}

@TECHREPORT{DvorakMNW11,
  author = {Wolfgang Dvo\v{r}\'ak and Michael Morak and Clemens Nopp and Stefan
	Woltran},
  title = {dynPARTIX - A Dynamic Programming Reasoner for Abstract Argumentation},
  institution = {CoRR},
  year = {2011},
  abstract = {The aim of this paper is to announce the release of a novel system
	for abstract argumentation which is based on decomposition and dynamic
	programming. We provide first experimental evaluations to show the
	feasibility of this approach.},
  ee = {http://arxiv.org/abs/1108.4804},
  journal = {CoRR},
  volume = {abs/1108.4804}
}

@ARTICLE{DvorakOS12,
  author = {Wolfgang Dvo\v{r}\'ak and Sebastian Ordyniak and Stefan Szeider},
  title = {Augmenting tractable fragments of abstract argumentation},
  journal = {Artificial Intelligence},
  year = {2012},
  volume = {186},
  pages = {157--173},
  number = {0},
  abstract = {We present a new approach to the efficient solution of important computational
	problems that arise in the context of abstract argumentation. Our
	approach makes known algorithms defined for restricted fragments
	generally applicable, at a computational cost that scales with the
	distance from the fragment. Thus, in a certain sense, we gradually
	augment tractable fragments. Surprisingly, it turns out that some
	tractable fragments admit such an augmentation and that others do
	not. More specifically, we show that the problems of Credulous and
	Skeptical Acceptance are fixed-parameter tractable when parameterized
	by the distance from the fragment of acyclic argumentation frameworks?for
	most semantics. Other tractable fragments such as the fragments of
	symmetrical and bipartite frameworks seem to prohibit an augmentation:
	the acceptance problems are already intractable for frameworks at
	distance 1 from the fragments.
	
	For our study we use a broad setting and consider several different
	semantics. For the algorithmic results we utilize recent advances
	in fixed-parameter tractability.},
  doi = {10.1016/j.artint.2012.03.002},
  issn = {0004-3702},
  url = {http://www.sciencedirect.com/science/article/pii/S0004370212000239}
}

@INPROCEEDINGS{DvorakPW10,
  author = {Wolfgang Dvo\v{r}\'ak and Reinhard Pichler and Stefan Woltran},
  title = {Towards Fixed-Parameter Tractable Algorithms for Argumentation},
  booktitle = {Proceedings of the 12th International Conference on the Principles
	of Knowledge Representation and Reasoning (KR'10)},
  year = {2010},
  editor = {Fangzhen Lin and Ulrike Sattler and Miroslaw Truszczynski},
  pages = {112-122},
  publisher = {AAAI Press},
  abstract = {Abstract argumentation frameworks have received a lot of interest
	in recent years. Most computational problems in this area are intractable
	but several tractable fragments have been identified. In particular,
	Dunne showed that many problems can be solved in linear time for
	argumentation frameworks of bounded tree-width. However, these tractability
	results, which were obtained via Courcelle's Theorem, do not directly
	lead to efficient algorithms. The goal of this paper is to turn the
	theoretical tractability results into efficient algorithms and to
	explore the potential of directed notions of tree-width for defining
	larger tractable fragments.}
}

@ARTICLE{DvorakPW12,
  author = {Wolfgang Dvo\v{r}\'ak and Reinhard Pichler and Stefan Woltran},
  title = {Towards fixed-parameter tractable algorithms for abstract argumentation},
  journal = {Artificial Intelligence},
  year = {2012},
  volume = {186},
  pages = {1 - 37},
  number = {0},
  abstract = {Abstract argumentation frameworks have received a lot of interest
	in recent years. Most computational problems in this area are intractable
	but several tractable fragments have been identified. In particular,
	Dunne showed that many problems can be solved in linear time for
	argumentation frameworks of bounded tree-width. However, these tractability
	results, which were obtained via Courcelle's Theorem, do not directly
	lead to efficient algorithms. The goal of this paper is to turn the
	theoretical tractability results into efficient algorithms and to
	explore the potential of directed notions of tree-width for defining
	larger tractable fragments. As a by-product, we will sharpen some
	known complexity results.},
  doi = {10.1016/j.artint.2012.03.005},
  issn = {0004-3702},
  keywords = {Abstract argumentation},
  url = {http://www.sciencedirect.com/science/article/pii/S0004370212000264}
}

@TECHREPORT{dbai-tr-2011-74,
  author = {Wolfgang Dvo\v{r}\'ak and Reinhard Pichler and Stefan Woltran},
  title = {Towards Fixed-Parameter Tractable Algorithms for Abstract Argumentation.},
  institution = {Technische Universit\"at Wien},
  year = {2011},
  type = {Technical Report},
  number = {DBAI-TR-2011-74},
  abstract = {Abstract argumentation frameworks have received a lot of interest
	in recent years. Most computational problems in this area are intractable
	but several tractable fragmentshave been identified. In particular,
	Dunne showed that many problems can be solved in linear time for
	argumentation frameworks of bounded tree-width. However, these tractability
	results, which were obtained via Courcelle?s Theorem, do not directly
	lead to efficient algorithms. The goal of this paper is to turn the
	theoretical tractability results into efficient algorithms and to
	explore the potential of directed notions of tree-width for defining
	larger tractable fragments. As a by-product, we will sharpen some
	known complexity results.},
  pdf = {http://www.dbai.tuwien.ac.at/research/report/dbai-tr-2011-74.pdf}
}

@INPROCEEDINGS{DvorakS12,
  author = {Wolfgang Dvo\v{r}\'ak and Christof Spanring},
  title = {Comparing the Expressiveness of Argumentation Semantics},
  booktitle = {Computational Models of Argument - Proceedings of COMMA 2012, Vienna,
	Austria, September 10-12, 2012},
  year = {2012},
  editor = {Bart Verheij and Stefan Szeider and Stefan Woltran},
  volume = {245},
  series = {Frontiers in Artificial Intelligence and Applications},
  pages = {261-272},
  publisher = {IOS Press},
  ee = {http://dx.doi.org/10.3233/978-1-61499-111-3-261},
  isbn = {978-1-61499-110-6}
}

@INPROCEEDINGS{DvorakSW10,
  author = {Wolfgang Dvo\v{r}\'ak and Stefan Szeider and Stefan Woltran},
  title = {Reasoning in Argumentation Frameworks of Bounded Clique-Width},
  booktitle = {Proceedings of the 3th Conference on Computational Models of Argument
	(COMMA 2010)},
  year = {2010},
  editor = {Pietro Baroni and Federico Cerutti and Massimiliano Giacomin and
	Guillermo R. Simari},
  series = {Frontiers in Artificial Intelligence and Applications},
  pages = {219-230},
  address = {Desenzano del Garda, Italy},
  month = {September 8-10},
  publisher = {IOS Press},
  abstract = {Most computational problems in the area of abstract argumentation
	are intractable, thus identifying tractable fragments and developing
	efficient algorithmsfor such fragments are important objectives towards
	practically efficient argumentation systems. One approach to tractability
	is to view abstract argumentation frameworks (AFs) as directed graphs
	and bound certain graph parameters. In particular, Dunne showed that
	many problems can be solved in linear time for AFs of bounded treewidth.
	In this paper we consider the graph-parameter clique-width, which
	is more general than treewidth. An additional advantage of clique-width
	over treewidth is that it applies well to directed graphs and takes
	the orientation of edges into account. We ?rst give theoretical tractability
	results for AFs of bounded clique-width and then introduce dynamic-programming
	algorithms for credulous and skeptical reasoning.}
}

@TECHREPORT{dbai-tr-2012-79,
  author = {Wolfgang Dvo\v{r}\'ak and Stefan Szeider and Stefan Woltran},
  title = {Abstract Argumentation via Monadic Second Order Logic.},
  institution = {Technische Universität Wien},
  year = {2012},
  type = {Technical Report},
  number = {DBAI-TR-2011-79},
  abstract = {We propose the formalism of ?Monadic Second-Order Logic? as a unifying
	framework for representing and reasoning with various semantics of
	abstract argumentation. We express a wide range of semantics within
	the proposed framework, including the semantics proposed by Dung,
	semi-stable, stage, cf2, and resolution-based semantics. We provide
	building blocks which make it easy and straight-forward to express
	further semantics. Expressing reasoning problems in abstract argumentation
	within Monadic Second-Order Logic not only shows that this logic
	can serve as a lingua franca for further investigations, but also
	directly yields important complexity results. In particular, we obtain
	that for argumentation frameworks with certain structural properties
	the main computational problems can all be solved in linear time.},
  pdf = {http://www.dbai.tuwien.ac.at/research/report/dbai-tr-2012-79.pdf}
}

@ARTICLE{DvorakW11,
  author = {Wolfgang Dvo\v{r}\'ak and Stefan Woltran},
  title = {On the Intertranslatability of Argumentation Semantics},
  journal = {J. Artif. Intell. Res. (JAIR)},
  year = {2011},
  volume = {41},
  pages = {445-475},
  abstract = {Translations between different nonmonotonic formalisms always have
	been an important topic in the field, in particular to understand
	the knowledge-representation capabilities those formalisms offer.
	We provide such an investigation in terms of different semantics
	proposed for abstract argumentation frameworks, a nonmonotonic yet
	simple formalism which received increasing interest within the last
	decade. Although the properties of these different semantics are
	nowadays well understood, there are no explicit results about intertranslatability.
	We provide such translations wrt. different properties and also give
	a few novel complexity results which underlie some negative results.},
  ee = {http://dx.doi.org/10.1613/jair.3318}
}

@ARTICLE{DvorakW10,
  author = {Wolfgang Dvo\v{r}\'ak and Stefan Woltran},
  title = {Complexity of semi-stable and stage semantics in argumentation frameworks},
  journal = {Inf. Process. Lett.},
  year = {2010},
  volume = {110},
  pages = {425-430},
  number = {11},
  abstract = {In this work, we answer two questions about the complexity of semi-stable
	semantics for abstract argumentation frameworks: we show PiP2 -completeness
	for the problem of deciding whether an argument is skeptically accepted,
	and respectively, SigmaP2 -completeness for the problem of deciding
	whether an argument is credulously accepted under the semi-stable
	semantics. Furthermore, we extend these complexity bounds to the
	according decision problems for stage semantics and discuss two approaches
	towards tractability.},
  doi = {10.1016/j.ipl.2010.04.005},
  ee = {http://dx.doi.org/10.1016/j.ipl.2010.04.005}
}

@INPROCEEDINGS{DvorakW10b,
  author = {Wolfgang Dvo\v{r}\'ak and Stefan Woltran},
  title = {On the Intertranslatability of Argumentation Semantics},
  booktitle = {Proceedings of the Conference on Thirty Years of Nonmonotonic Reasoning
	(NonMon@30)},
  year = {2010},
  address = {Lexington, KY, USA},
  month = {October 22-25},
  abstract = {Translations between different nonmonotonic formalisms always have
	been an important topic in the field, in particular to understand
	the knowledge- representation capabilities those formalisms offer.
	We provide such an investigation in terms of different semantics
	proposed for abstract argumentation frameworks, a nonmonotonic yet
	simple formalism which received increasing interest within the last
	decade. Although the properties of these different semantics are
	nowadays well understood, there are no explicit results about intertranslatability.
	We provide such translations wrt. different properties and also give
	a few novel complexity results which underlie some negative results.},
  url = {http://www.cs.uky.edu/~marek/nonmonat30.dir/dvorakWoltran.pdf}
}

@TECHREPORT{DvorakW09,
  author = {Wolfgang Dvo\v{r}\'ak and Stefan Woltran},
  title = {Technical Note: Complexity of Stage Semantics in Argumentation Frameworks},
  institution = {Technische Universit\"at Wien, Database and Artificial Intelligence
	Group},
  year = {2009},
  number = {DBAI-TR-2009-66},
  abstract = {In this work, we answer two questions about the complexity of semi-stable
	semantics for abstract argumentation frameworks raised by Dunne and
	Caminada (2008): weshow PiP2 -completeness for the problem of deciding
	whether an argument is skeptically accepted, and respectively, SigmaP2
	-completeness for the problem of deciding whether an argument is
	credulously accepted under the semi-stable semantics. Furthermore,
	we extend these complexity bounds to the according decision problems
	for stage semantics as introduced by Verheij (1997). We also discuss
	two approaches towards tractability: ?rst, we prove that the problems
	under consideration are ?xed-parameter tractable with respect totree-width;
	second, we show that the problems remain intractable when considering
	frameworks of bounded cycle-rank.},
  url = {http://www.dbai.tuwien.ac.at/research/report/dbai-tr-2009-66.pdf}
}

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