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18
Semiring induced valuation algebras: Exact and approximate local computation algorithms
, 2008
"... ..."
Local computation in covering join trees
, 2004
"... In recent years, the computation of marginals out of a factorization of valuations has been studied in detail. There are several algorithms solving this task such that the domains of the intermediate results remain small. These methods are essentially based on message passing schemes on join trees. ..."
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Cited by 8 (4 self)
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In recent years, the computation of marginals out of a factorization of valuations has been studied in detail. There are several algorithms solving this task such that the domains of the intermediate results remain small. These methods are essentially based on message passing schemes on join trees. Every node’s label equals the domain of a factor or the domain of the combination of several factors. However, we are usually forced to use covering join trees where the domains of the factors are only supposed to be contained in the labels of the nodes. A major drawback of the use of covering join trees is that we have to ensure that all marginals to be computed are well defined. Until yet, this problem was simplified by filling the nodes with neutral elements bearing the desired, bigger domain. Although mathematical correct, this is not feasible for practical purposes, since neutral elements tend to contain infinite elements. We will see that such unfavorable extensions are not needed. Of particular interest in this paper are the collect algorithm, the ShenoyShafer (Shenoy & Shafer,
Solving Decision Problems with Limited Information
"... We present a new algorithm for exactly solving decisionmaking problems represented as an influence diagram. We do not require the usual assumptions of no forgetting and regularity, which allows us to solve problems with limited information. The algorithm, which implements a sophisticated variable e ..."
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Cited by 7 (3 self)
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We present a new algorithm for exactly solving decisionmaking problems represented as an influence diagram. We do not require the usual assumptions of no forgetting and regularity, which allows us to solve problems with limited information. The algorithm, which implements a sophisticated variable elimination procedure, is empirically shown to outperform a stateoftheart algorithm in randomly generated problems of up to 150 variables and 10 64 strategies. 1
Solving limited memory influence diagrams. ArXiv:1109.1754v2 [cs.AI
, 2011
"... We present a new algorithm for exactly solving decision making problems represented as influence diagrams. We do not require the usual assumptions of no forgetting and regularity; this allows us to solve problems with simultaneous decisions and limited information. The algorithm is empirically shown ..."
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Cited by 7 (4 self)
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We present a new algorithm for exactly solving decision making problems represented as influence diagrams. We do not require the usual assumptions of no forgetting and regularity; this allows us to solve problems with simultaneous decisions and limited information. The algorithm is empirically shown to outperform a stateoftheart algorithm on randomly generated problems of up to 150 variables and 10 64 solutions. We show that these problems are NPhard even if the underlying graph structure of the problem has low treewidth and the variables take on a bounded number of states, and that they admit no provably good approximation if variables can take on an arbitrary number of states. 1.
Updating credal networks is approximable in polynomial time
 International Journal of Approximate Reasoning
"... This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. ..."
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Cited by 6 (5 self)
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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Chisci "An approach to Threat Assessment Based on Evidential Networks
 Proc. Int. Conf. Fusion 2007 Conference
"... Abstract — The paper develops an information fusion system that aims at supporting a commander’s decision making by providing an assessment of threat, that is an estimate of the extent to which an enemy platform poses a threat based on evidence about its intent and capability. Threat is modelled in ..."
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Cited by 4 (1 self)
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Abstract — The paper develops an information fusion system that aims at supporting a commander’s decision making by providing an assessment of threat, that is an estimate of the extent to which an enemy platform poses a threat based on evidence about its intent and capability. Threat is modelled in the framework of the valuationbased system (VBS), by a network of entities and relationships between them. The uncertainties in the relationships are represented by belief functions as defined in the theory of evidence. Hence the resulting network for reasoning is referred to as an evidential network. Local computations in the evidential network are carried out by inward propagation on the underlying joint binary tree. This allows the dynamic nature of the external evidence, which drives the evidential network, to be taken into account by recomputing only the affected paths in the joint binary tree.
An application of evidential networks to threat assessment
 IEEE Transactions on Aerospace and Electronic Systems
, 2009
"... Abstract Decision makers operating in modern defence theatres need to comprehend and reason with huge quantities of potentially uncertain and imprecise data in a timely fashion. In this paper, an automatic information fusion system is developed which aims at supporting a commander's decision m ..."
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Cited by 4 (1 self)
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Abstract Decision makers operating in modern defence theatres need to comprehend and reason with huge quantities of potentially uncertain and imprecise data in a timely fashion. In this paper, an automatic information fusion system is developed which aims at supporting a commander's decision making by providing a threat assessment, that is an estimate of the extent to which an enemy platform poses a threat based on evidence about its intent and capability. Threat is modelled by a network of entities and relationships between them, while the uncertainties in the relationships are represented by belief functions as defined in the theory of evidence. To support the implementation of the threat assessment functionality, an efficient valuationbased reasoning scheme, referred to as an evidential network, is developed. To reduce computational overheads, the scheme performs local computations in the network by applying an inward propagation algorithm to the underlying binary join tree. This allows the dynamic nature of the external evidence, which drives the evidential network, to be taken into account by recomputing only the affected paths in the binary join tree.
Minimizing communication costs of distributed local computation
, 2005
"... A valuation algebra offers a suitable framework to represent knowledge and information. Based on this framework, several algorithms to process knowledge and pooled under the name local computation were mapped out in recent years. This paper proposes an extension of the valuation algebra framework th ..."
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Cited by 3 (1 self)
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A valuation algebra offers a suitable framework to represent knowledge and information. Based on this framework, several algorithms to process knowledge and pooled under the name local computation were mapped out in recent years. This paper proposes an extension of the valuation algebra framework that allows to express the costs of transmitting valuations between network hosts. Based on this model, we estimate the total computation costs caused by the local computation architectures and observe under which constraints these costs can be minimized. Once a sufficient condition is identified, we present an
Threat assessment using evidential networks
 in 10th International Conference on Information Fusion
, 2007
"... Decision makers operating in modern defence theatres need to comprehend and reason with huge quantities of potentially uncertain and imprecise data in a timely fashion. In this paper, an automatic information fusion system is developed which aims at supporting a commander’s decision making by provid ..."
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Cited by 2 (1 self)
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Decision makers operating in modern defence theatres need to comprehend and reason with huge quantities of potentially uncertain and imprecise data in a timely fashion. In this paper, an automatic information fusion system is developed which aims at supporting a commander’s decision making by providing a threat assessment, that is an estimate of the extent to which an enemy platform poses a threat based on evidence about its intent and capability. Threat is modelled by a network of entities and relationships between them, while the uncertainties in the relationships are represented by belief functions as defined in the theory of evidence. To support the implementation of the threat assessment functionality, an efficient valuationbased reasoning scheme, referred to as an evidential network, is developed. To reduce computational overheads, the scheme performs local computations in the network by applying an inward propagation algorithm to the underlying binary join tree. This allows the dynamic nature of the external evidence, which drives the evidential network, to be taken into account by recomputing only the affected paths in the binary join tree.
Local Computation in Covering Join Trees Part #2 Updating in Local Computation ∗
, 2006
"... Local computation on covering join trees provides a solution for query answering in several different fields, such as relational databases, belief functions, constraint satisfaction, Gaussian potentials and many more. The algebraic structure behind is a generic framework for information processing k ..."
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Cited by 1 (0 self)
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Local computation on covering join trees provides a solution for query answering in several different fields, such as relational databases, belief functions, constraint satisfaction, Gaussian potentials and many more. The algebraic structure behind is a generic framework for information processing known as valuation algebras (Kohlas, 2003). In this paper we discuss how new information pieces can be added to the old information, i.e. how to use former computed results to answer the queries in the new situation. A task which will be referred to as updating. The domains of the new information pieces are possibly not covered by any node of the join tree. Since the construction of a new covering join tree may be computationally expensive and makes it harder or even impossible to reuse already available results, we introduce several methods to modify join trees locally. We will see that this enables updating approaches for all wellknown architectures for local compuation like ShenoyShafer, LauritzenSpiegelhalter and HUGIN. As