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17
On the consistencyof cardinal direction constraints
 Artificial Intelligence
, 2005
"... We present a formal model for qualitative spatial reasoning with cardinal directions utilizing a coordinate system. Then, we study the problem of checking the consistency of a set of cardinal direction constraints. We introduce the first algorithm for this problem, prove its correctness and analyz ..."
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Cited by 14 (2 self)
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We present a formal model for qualitative spatial reasoning with cardinal directions utilizing a coordinate system. Then, we study the problem of checking the consistency of a set of cardinal direction constraints. We introduce the first algorithm for this problem, prove its correctness and analyze its computational complexity. Using the above algorithm, we prove that the consistency checking of a set of basic (i.e., nondisjunctive) cardinal direction constraints can be performed in O(n5) time. We also show that the consistency checking of a set of unrestricted (i.e., disjunctive and nondisjunctive) cardinal direction constraints is NPcomplete. Finally, we briefly discuss an extension to the basic model and outline an algorithm for the consistency checking problem of this extension. 1
SXPath: extending XPath towards spatial querying on web documents
 Proc. VLDB Endow
, 2010
"... All intext references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately. ..."
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Cited by 9 (0 self)
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All intext references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Thinking Inside the Box: A Comprehensive Spatial Representation for Video Analysis
"... Successful analysis of video data requires an integration of techniques from KR, Computer Vision, and Machine Learning. Being able to detect and to track objects as well as extracting their changing spatial relations with other objects is one approach to describing and detecting events. Different ki ..."
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Cited by 7 (6 self)
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Successful analysis of video data requires an integration of techniques from KR, Computer Vision, and Machine Learning. Being able to detect and to track objects as well as extracting their changing spatial relations with other objects is one approach to describing and detecting events. Different kinds of spatial relations are important, including topology, direction, size, and distance between objects as well as changes of those relations over time. Typically these kinds of relations are treated separately, which makes it difficult to integrate all the extracted spatial information. We present a uniform and comprehensive spatial representation of moving objects that includes all the above spatial/temporal aspects, analyse different properties of this representation and demonstrate that it is suitable for video analysis.
Interaction and Experience  Situated Agents and Sketching
, 2002
"... Cognitive studies of designers often involve sketching, but studies using artificial intelligence often apply a search paradigm. Sketching is an interaction between an agent and an environment. Perception influences how shape rules are applied, and the application of the rules influences future perc ..."
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Cited by 5 (3 self)
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Cognitive studies of designers often involve sketching, but studies using artificial intelligence often apply a search paradigm. Sketching is an interaction between an agent and an environment. Perception influences how shape rules are applied, and the application of the rules influences future perception. One motivation behind our work is to computationally model an autonomous design agent that is based on interaction; an agent that can interact with an external representation of a developing design. We describe an interactive model of an agent. In our model an agent has six parts: sensors, perceptors, a conceptor, an action activator, a hypothesiser, and effectors. In this paper we describe our model and a trial implementation involving learning, perception and action activation 1.
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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Cited by 4 (1 self)
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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.
An Ontologybased Multilevel Robot Architecture for Learning from Experiences
"... One way to improve the robustness and flexibility of robot performance is to let the robot learn from its experiences. In this paper, we describe the architecture and knowledgerepresentation framework for a service robot being developed in the EU project RACE, and present examples illustrating how ..."
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Cited by 3 (1 self)
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One way to improve the robustness and flexibility of robot performance is to let the robot learn from its experiences. In this paper, we describe the architecture and knowledgerepresentation framework for a service robot being developed in the EU project RACE, and present examples illustrating how learning from experiences will be achieved. As a unique innovative feature, the framework combines memory records of lowlevel robot activities with ontologybased highlevel semantic descriptions. 1
Reasoning with cardinal directions: An efficient algorithm
 Proceedings of the TwentyThird AAAI Conference on Artificial Intelligence (AAAI08
, 2008
"... Direction relations between extended spatial objects are important commonsense knowledge. Recently, Goyal and Egenhofer proposed a formal model, called Cardinal Direction Calculus (CDC), for representing direction relations between connected plane regions. CDC is perhaps the most expressive qualit ..."
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Cited by 2 (1 self)
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Direction relations between extended spatial objects are important commonsense knowledge. Recently, Goyal and Egenhofer proposed a formal model, called Cardinal Direction Calculus (CDC), for representing direction relations between connected plane regions. CDC is perhaps the most expressive qualitative calculus for directional information, and has attracted increasing interest from areas such as artificial intelligence, geographical information science, and image retrieval. Given a network of CDC constraints, the consistency problem is deciding if the network is realizable by connected regions in the real plane. This paper provides a cubic algorithm for checking consistency of basic CDC constraint networks. As one byproduct, we also show that any consistent network of CDC constraints has a canonical realization in digital plane. The cubic algorithm can also been adapted to cope with disconnected regions, in which case the current best algorithm is of time complexity O(n5).
A method for metric temporal reasoning
 In AAAI/IAAI
, 2002
"... Several methods for temporal reasoning with metric time have been suggested—for instance, Horn Disjunctive Linear Relations (Horn DLRs). However, it has been noted that implementing this algorithm is nontrivial since it builds on fairly complicated polynomialtime algorithms for linear programming ..."
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Cited by 1 (0 self)
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Several methods for temporal reasoning with metric time have been suggested—for instance, Horn Disjunctive Linear Relations (Horn DLRs). However, it has been noted that implementing this algorithm is nontrivial since it builds on fairly complicated polynomialtime algorithms for linear programming. Instead, an alternative approach which augments Allen’s interval algebra with a Simple Temporal Problem (STP) has been suggested (Condotta, 2000). In this paper, we present a new pointbased approach STP ∗ for reasoning about metric temporal constraints. STP ∗ subsumes the tractable preconvex fragment of the augmented interval algebra and can be viewed as a slightly restricted version of Horn DLRs. We give an easily implementable algorithm for deciding satisfiability of STP ∗ and demonstrate experimentally its efficiency. We also give a method for finding solutions to consistent STP ∗ problem instances.
Computing and Networking of the Italian CNR
"... Querying data from presentation formats like HTML, for purposes such as information extraction, requires the consideration of tree structures as well as the consideration of spatial relationships between laid out elements. The underlying rationale is that frequently the rendering of tree structures ..."
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Querying data from presentation formats like HTML, for purposes such as information extraction, requires the consideration of tree structures as well as the consideration of spatial relationships between laid out elements. The underlying rationale is that frequently the rendering of tree structures is very involved and undergoing more frequent updates than the resulting layout structure. Therefore, in this paper, we present Spatial XPath (SXPath), an extension of XPath 1.0 that allows for inclusion of spatial navigation primitives into the language resulting in conceptually simpler queries on Web documents. The SXPath language is based on a combination of a spatial algebra with formal descriptions of XPath navigation, and maintains polynomial time combined complexity. Practical experiments demonstrate the usability of SXPath. 1.
Qualitative Spatial Representation and Reasoning
"... The need for spatial representations and spatial reasoning is ubiquitous in AI—from robot planning and navigation, to interpreting visual inputs, to understanding natural language—in all these cases the need to represent and reason about spatial aspects of the world is of key importance. Related fie ..."
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The need for spatial representations and spatial reasoning is ubiquitous in AI—from robot planning and navigation, to interpreting visual inputs, to understanding natural language—in all these cases the need to represent and reason about spatial aspects of the world is of key importance. Related fields of research, such as geographic information