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RCC8 Is Polynomial on Networks of Bounded Treewidth
 PROCEEDINGS OF THE TWENTYSECOND INTERNATIONAL JOINT CONFERENCE ON ARTIFICIAL INTELLIGENCE
"... We construct an homogeneous (and ωcategorical) representation of the relation algebra RCC8, which is one of the fundamental formalisms for spatial reasoning. As a consequence we obtain that the network consistency problem for RCC8 can be solved in polynomial time for networks of bounded treewidth. ..."
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We construct an homogeneous (and ωcategorical) representation of the relation algebra RCC8, which is one of the fundamental formalisms for spatial reasoning. As a consequence we obtain that the network consistency problem for RCC8 can be solved in polynomial time for networks of bounded treewidth.
Compactness and its implications for qualitative spatial and temporal reasoning
 PROCEEDINGS OF THE 13TH INTERNATIONAL CONFERENCE ON PRINCIPLES OF KNOWLEDGE REPRESENTATION AND REASONING (KR
, 2012
"... A constraint satisfaction problem has compactness if any infinite set of constraints is satisfiable whenever all its finite subsets are satisfiable. We prove a sufficient condition for compactness, which holds for a range of problems including those based on the wellknown Interval Algebra (IA) and ..."
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A constraint satisfaction problem has compactness if any infinite set of constraints is satisfiable whenever all its finite subsets are satisfiable. We prove a sufficient condition for compactness, which holds for a range of problems including those based on the wellknown Interval Algebra (IA) and RCC8. Furthermore, we show that compactness leads to a useful necessary and sufficient condition for the recently introduced patchwork property, namely that patchwork holds exactly when every satisfiable finite network (i.e., set of constraints) has a canonical solution, that is, a solution that can be extended to a solution for any satisfiable finite extension of the network. Applying these general theorems to qualitative reasoning, we obtain important new results as well as significant strengthenings of previous results regarding IA, RCC8, and their fragments and extensions. In particular, we show that all the maximal tractable fragments of IA and RCC8 (containing the base relations) have patchwork and canonical solutions as long as networks are algebraically closed.
Methodologies for qualitative spatial and temporal reasoning application design
 In S. M. Hazarika (Ed.), Qualitative Spatiotemporal Representation and Reasoning. Trends and Future Directions. Hershey: IGI Global
, 2011
"... Although a wide range of sophisticated qualitative spatial and temporal reasoning (QSTR) formalisms have now been developed, there are relatively few applications that apply these commonsense methods. To address this problem we are developing methodologies that support QSTR application design. We es ..."
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Although a wide range of sophisticated qualitative spatial and temporal reasoning (QSTR) formalisms have now been developed, there are relatively few applications that apply these commonsense methods. To address this problem we are developing methodologies that support QSTR application design. We establish a theoretical foundation for QSTR applications that includes the roles of application designers and users. We adapt formal software requirements that allow a designer to specify the customer’s operational requirements and the functional requirements of a QSTR application. We present design patterns for organising the components of QSTR applications, and a methodology for defining high level neighbourhoods that are derived from the system structure. Finally, we develop a methodology for QSTR application validation by defining a complexity metric called Hcomplexity that is used in test coverage analysis for assessing the quality of unit and integration test sets. Over the last two and a half decades researchers have made significant progress in the theoretical foundations and analysis of qualitative spatial and temporal reasoning (QSTR) calculi, and a
Consistency of Chordal RCC8 Networks
"... Abstract—We consider chordal RCC8 networks and show that we can check their consistency by enforcing partial path consistency with weak composition. We prove this by using the fact that RCC8 networks with relations from the maximal tractable subsets Ĥ8, C8, and Q8 of RCC8 have the patchwork pro ..."
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Abstract—We consider chordal RCC8 networks and show that we can check their consistency by enforcing partial path consistency with weak composition. We prove this by using the fact that RCC8 networks with relations from the maximal tractable subsets Ĥ8, C8, and Q8 of RCC8 have the patchwork property. The use of partial path consistency has important practical consequences that we demonstrate with the implementation of the new reasoner PyRCC85, which is developed by extending the state of the art reasoner PyRCC8. Given an RCC8 network with only tractable RCC8 relations, we show that it can be solved very efficiently with PyRCC85 by making its underlying constraint graph chordal and running path consistency on this sparse graph instead of the completion of the given network. In the same way, partial path consistency can be used as the consistency checking step in backtracking algorithms for networks with arbitrary RCC8 relations resulting in very improved pruning for sparse networks while incurring a penalty for dense networks. I.
A QUALITATIVE REASONING APPROACH FOR IMPROVING QUERY RESULTS FOR SKETCHBASED QUERIES BY TOPOLOGICAL ANALYSIS OF SPATIAL AGGREGATION
, 2010
"... iii ..."
In Defense of Large Qualitative Calculi
"... The next challenge in qualitative spatial and temporal reasoning is to develop calculi that deal with different aspects of space and time. One approach to achieve this is to combine existing calculi that cover the different aspects. This, however, can lead to calculi that have a very large number of ..."
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The next challenge in qualitative spatial and temporal reasoning is to develop calculi that deal with different aspects of space and time. One approach to achieve this is to combine existing calculi that cover the different aspects. This, however, can lead to calculi that have a very large number of relations and it is a matter of ongoing discussions within the research community whether such large calculi are too large to be useful. In this paper we develop a procedure for reasoning about some of the largest known calculi, the Rectangle Algebra and the Block Algebra with about 10 661 relations. We demonstrate that reasoning over these calculi is possible and can be done efficiently in many cases. This is a clear indication that one of the main goals of the field can be achieved: highly expressive spatial and temporal representations that support efficient reasoning. 1.
Author manuscript, published in "12th International Conference on Principles of Knowledge Representation and Reasoning (KR'10), Toronto: Canada (2010)" A Class of ⋄ fconsistencies for Qualitative Constraint Networks
, 2013
"... In this paper, we introduce a new class of local consistencies, called ⋄ fconsistencies, for qualitative constraint networks. Each consistency of this class is based on weak composition (⋄) and a mapping f that provides a covering for each relation. We study the connections existing between some pr ..."
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In this paper, we introduce a new class of local consistencies, called ⋄ fconsistencies, for qualitative constraint networks. Each consistency of this class is based on weak composition (⋄) and a mapping f that provides a covering for each relation. We study the connections existing between some properties of mappings f and the relative inference strength of ⋄ fconsistencies. The consistency obtained by the usual closure under weak composition is shown to be the weakest element of the class, and new promising perspectives are shown to be opened by ⋄ fconsistencies stronger than weak composition. We also propose a generic algorithm that allows us to compute the closure of qualitative constraint networks under any “wellbehaved ” consistency of the class. The experimentation that we have conducted on qualitative constraint networks from the Interval Algebra shows the interest of these new local consistencies, in particular for the consistency problem.
SAT vs. Search for Qualitative Temporal Reasoning
"... Abstract. Empirical data from recent work has indicated that SATbased solvers can outperform native searchbased solvers on certain classes of problems in qualitative temporal reasoning, particularly over the Interval Algebra (IA). The present work shows that, for reasoning with IA, SAT strictly dom ..."
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Abstract. Empirical data from recent work has indicated that SATbased solvers can outperform native searchbased solvers on certain classes of problems in qualitative temporal reasoning, particularly over the Interval Algebra (IA). The present work shows that, for reasoning with IA, SAT strictly dominates search in theoretical power: (1) We present a SAT encoding of IA that simulates the use of tractable subsets in native solvers. (2) We show that the refutation of any inconsistent IA network can always be done by SAT (via our new encoding) as efficiently as by native search. (3) We exhibit a class of IA networks that provably require exponential time to refute by native search, but can be refuted by SAT in polynomial time. 1
Nogoods in Qualitative Constraintbased Reasoning
"... Abstract. The prevalent method of increasing reasoning efficiency in the domain of qualitative constraintbased spatial and temporal reasoning is to use domain splitting based on socalled tractable subclasses. In this paper we analyze the application of nogood learning with restarts in combination ..."
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Abstract. The prevalent method of increasing reasoning efficiency in the domain of qualitative constraintbased spatial and temporal reasoning is to use domain splitting based on socalled tractable subclasses. In this paper we analyze the application of nogood learning with restarts in combination with domain splitting. Previous results on nogood recording in the constraint satisfaction field feature learnt nogoods as a global constraint that allows for enforcing generalized arc consistency. We present an extension of such a technique capable of handling domain splitting, evaluate its benefits for qualitative constraintbased reasoning, and compare it with alternative approaches. 1
A Class of ⋄ fconsistencies for Qualitative Constraint Networks
"... In this paper, we introduce a new class of local consistencies, called ⋄ fconsistencies, for qualitative constraint networks. Each consistency of this class is based on weak composition (⋄) and a mapping f that provides a covering for each relation. We study the connections existing between some pr ..."
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In this paper, we introduce a new class of local consistencies, called ⋄ fconsistencies, for qualitative constraint networks. Each consistency of this class is based on weak composition (⋄) and a mapping f that provides a covering for each relation. We study the connections existing between some properties of mappings f and the relative inference strength of ⋄ fconsistencies. The consistency obtained by the usual closure under weak composition is shown to be the weakest element of the class, and new promising perspectives are shown to be opened by ⋄ fconsistencies stronger than weak composition. We also propose a generic algorithm that allows us to compute the closure of qualitative constraint networks under any “wellbehaved ” consistency of the class. The experimentation that we have conducted on qualitative constraint networks from the Interval Algebra shows the interest of these new local consistencies, in particular for the consistency problem.