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Augmenting Tractable Fragments of Abstract Argumentation
 PROCEEDINGS OF THE TWENTYSECOND INTERNATIONAL JOINT CONFERENCE ON ARTIFICIAL INTELLIGENCE
"... We present a new and compelling 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 ..."
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Cited by 13 (4 self)
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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 fixedparameter
Conjunctive queries for a tractable fragment of OWL 1.1
 Proc. 6th Int. Semantic Web Conf. (ISWC’07
, 2007
"... Abstract. Despite the success of the Web Ontology Language OWL, the development of expressive means for querying OWL knowledge bases is still an open issue. In this paper, we investigate how a very natural and desirable form of queries—namely conjunctive ones—can be used in conjunction with OWL suc ..."
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Cited by 33 (9 self)
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such that one of the major design criteria of the latter—namely decidability—can be retained. More precisely, we show that querying the tractable fragment EL++ of OWL 1.1 is decidable. We also provide a complexity analysis and show that querying unrestricted EL++ is undecidable. 1
Conjunctive Queries for a Tractable Fragment of OWL 1.1 ⋆
"... Abstract. Despite the success of the Web Ontology Language OWL, the development of expressive means for querying OWL knowledge bases is still an open issue. In this paper, we investigate how a very natural and desirable form of queries—namely conjunctive ones—can be used in conjunction with OWL suc ..."
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such that one of the major design criteria of the latter—namely decidability—can be retained. More precisely, we show that querying the tractable fragment EL++ of OWL 1.1 is decidable. We also provide a complexity analysis and show that querying unrestricted EL++ is undecidable. 1
Maximal Tractable Fragments of the Region Connection Calculus: A Complete Analysis
 In Proceedings of the 16th International Joint Conference on Artificial Intelligence (IJCAI99
, 1999
"... We present a general method for proving tractability of reasoning over disjunctions of jointly exhaustive and pairwise disjoint relations. Examples of these kinds of relations are Allen's temporal interval relations and their spatial counterpart, the RCC8 relations by Randell, Cui, and Cohn. Ap ..."
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Cited by 47 (15 self)
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We present a general method for proving tractability of reasoning over disjunctions of jointly exhaustive and pairwise disjoint relations. Examples of these kinds of relations are Allen's temporal interval relations and their spatial counterpart, the RCC8 relations by Randell, Cui, and Cohn
Compilation of queryrewriting problems into tractable fragments of propositional logic
 In AAAI
"... We consider the problem of rewriting a query efficiently using materialized views. In the context of information integration, this problem has received significant attention in the scope of emerging infrastructures such as WWW, Semantic Web, Grid, and P2P which require efficient algorithms. The prob ..."
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Cited by 11 (3 self)
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We consider the problem of rewriting a query efficiently using materialized views. In the context of information integration, this problem has received significant attention in the scope of emerging infrastructures such as WWW, Semantic Web, Grid, and P2P which require efficient algorithms. The problem is in general intractable, and the current algorithms do not scale well when the number of views or the size of the query grow. We show however that this problem can be encoded as a propositional theory in CNF such that its models are in correspondence with the rewritings of the query. The theory is then compiled into a normal form, that is called dDNNF and supports several operations like model counting and enumeration in polynomial time (in the size of the compiled theory), for computing the rewritings. Although this method is also intractable in the general case, it is not necessarily so in all cases. We have developed, along these lines and from offtheshelf propositional engines, novel algorithms for finding maximallycontained rewritings of the query given the set of accessible resources (views). The algorithms scale much better than the current stateoftheart algorithm, the MiniCon algorithm, over a large number of benchmarks and show in some cases improvements in performance of a couple ordersofmagnitude.
On the Complexity of Qualitative Spatial Reasoning: A Maximal Tractable Fragment of the Region Connection Calculus
 Artificial Intelligence
, 1997
"... The computational properties of qualitative spatial reasoning have been investigated to some degree. However, the question for the boundary between polynomial and NPhard reasoning problems has not been addressed yet. In this paper we explore this boundary in the "Region Connection Calculus&quo ..."
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Cited by 141 (23 self)
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" RCC8. We extend Bennett's encoding of RCC8 in modal logic. Based on this encoding, we prove that reasoning is NPcomplete in general and identify a maximal tractable subset of the relations in RCC8 that contains all base relations. Further, we show that for this subset path
Consequencebased datatype reasoning in EL: Identifying the tractable fragments
, 2009
"... The current dissertation suggests a consequencebased reasoning approach for the EL ⊥ description logic with numerical datatypes. It provides a set of saturation rules which are used in the formulation of a polynomial classfication algorithm. Furthermore, it introduces the notion of safety which i ..."
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Cited by 1 (1 self)
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The current dissertation suggests a consequencebased reasoning approach for the EL ⊥ description logic with numerical datatypes. It provides a set of saturation rules which are used in the formulation of a polynomial classfication algorithm. Furthermore, it introduces the notion of safety which is a property that numerical datatypes exhibit and guarantees the preservation of polynomiality. The proposed algorithm is proved to be complete only for the safe datatypes. Additionally, the corresponding reasoning problem for nonsafe datatypes is proved to be EXPTIMEhard. Apart from that, a classification of specific instances of datatypes is attempted. Finally, the present work, based on the results it produces, suggest a modification of the EL Profile in OWL 2 in order to add datatype features, which are currently available only in OWL 2. ii Acknowledgements
Tractable inference for complex stochastic processes
 In Proc. UAI
, 1998
"... The monitoring and control of any dynamic system depends crucially on the ability to reason about its current status and its future trajectory. In the case of a stochastic system, these tasks typically involve the use of a belief state—a probability distribution over the state of the process at a gi ..."
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Cited by 306 (15 self)
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The monitoring and control of any dynamic system depends crucially on the ability to reason about its current status and its future trajectory. In the case of a stochastic system, these tasks typically involve the use of a belief state—a probability distribution over the state of the process at a given point in time. Unfortunately, the state spaces of complex processes are very large, making an explicit representation of a belief state intractable. Even in dynamic Bayesian networks (DBNs), where the process itself can be represented compactly, the representation of the belief state is intractable. We investigate the idea of maintaining a compact approximation to the true belief state, and analyze the conditions under which the errors due to the approximations taken over the lifetime of the process do not accumulate to make our answers completely irrelevant. We show that the error in a belief state contracts exponentially as the process evolves. Thus, even with multiple approximations, the error in our process remains bounded indefinitely. We show how the additional structure of a DBN can be used to design our approximation scheme, improving its performance significantly. We demonstrate the applicability of our ideas in the context of a monitoring task, showing that orders of magnitude faster inference can be achieved with only a small degradation in accuracy. 1
Qualitative Simulation
 Artificial Intelligence
, 2001
"... Qualitative simulation predicts the set of possible behaviors... ..."
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Cited by 513 (31 self)
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Qualitative simulation predicts the set of possible behaviors...
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