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19,902
Model Based Framework for Estimating Mutation Rate of Hepatitis C Virus in Egypt
cs.AI
Hepatitis C virus (HCV) is a widely spread disease all over the world. HCV has very high mutation rate that makes it resistant to antibodies. Modeling HCV to identify the virus mutation process is essential to its detection and predicting its evolution. This paper presents a model based framework for estimating mutatio...
computer science
19,903
RES - a Relative Method for Evidential Reasoning
cs.AI
In this paper we describe a novel method for evidential reasoning [1]. It involves modelling the process of evidential reasoning in three steps, namely, evidence structure construction, evidence accumulation, and decision making. The proposed method, called RES, is novel in that evidence strength is associated with an ...
computer science
19,904
Optimizing Causal Orderings for Generating DAGs from Data
cs.AI
An algorithm for generating the structure of a directed acyclic graph from data using the notion of causal input lists is presented. The algorithm manipulates the ordering of the variables with operations which very much resemble arc reversal. Operations are only applied if the DAG after the operation represents at lea...
computer science
19,905
Modal Logics for Qualitative Possibility and Beliefs
cs.AI
Possibilistic logic has been proposed as a numerical formalism for reasoning with uncertainty. There has been interest in developing qualitative accounts of possibility, as well as an explanation of the relationship between possibility and modal logics. We present two modal logics that can be used to represent and reas...
computer science
19,906
Structural Controllability and Observability in Influence Diagrams
cs.AI
Influence diagram is a graphical representation of belief networks with uncertainty. This article studies the structural properties of a probabilistic model in an influence diagram. In particular, structural controllability theorems and structural observability theorems are developed and algorithms are formulated. Cont...
computer science
19,907
Lattice-Based Graded Logic: a Multimodal Approach
cs.AI
Experts do not always feel very, comfortable when they have to give precise numerical estimations of certainty degrees. In this paper we present a qualitative approach which allows for attaching partially ordered symbolic grades to logical formulas. Uncertain information is expressed by means of parameterized modal ope...
computer science
19,908
Dynamic Network Models for Forecasting
cs.AI
We have developed a probabilistic forecasting methodology through a synthesis of belief network models and classical time-series analysis. We present the dynamic network model (DNM) and describe methods for constructing, refining, and performing inference with this representation of temporal probabilistic knowledge. Th...
computer science
19,909
Reformulating Inference Problems Through Selective Conditioning
cs.AI
We describe how we selectively reformulate portions of a belief network that pose difficulties for solution with a stochastic-simulation algorithm. With employ the selective conditioning approach to target specific nodes in a belief network for decomposition, based on the contribution the nodes make to the tractability...
computer science
19,910
Entropy and Belief Networks
cs.AI
The product expansion of conditional probabilities for belief nets is not maximum entropy. This appears to deny a desirable kind of assurance for the model. However, a kind of guarantee that is almost as strong as maximum entropy can be derived. Surprisingly, a variant model also exhibits the guarantee, and for many ca...
computer science
19,911
Parallelizing Probabilistic Inference: Some Early Explorations
cs.AI
We report on an experimental investigation into opportunities for parallelism in beliefnet inference. Specifically, we report on a study performed of the available parallelism, on hypercube style machines, of a set of randomly generated belief nets, using factoring (SPI) style inference algorithms. Our results indicate...
computer science
19,912
Objection-Based Causal Networks
cs.AI
This paper introduces the notion of objection-based causal networks which resemble probabilistic causal networks except that they are quantified using objections. An objection is a logical sentence and denotes a condition under which a, causal dependency does not exist. Objection-based causal networks enjoy almost all ...
computer science
19,913
A Symbolic Approach to Reasoning with Linguistic Quantifiers
cs.AI
This paper investigates the possibility of performing automated reasoning in probabilistic logic when probabilities are expressed by means of linguistic quantifiers. Each linguistic term is expressed as a prescribed interval of proportions. Then instead of propagating numbers, qualitative terms are propagated in accord...
computer science
19,914
Possibilistic Assumption based Truth Maintenance System, Validation in a Data Fusion Application
cs.AI
Data fusion allows the elaboration and the evaluation of a situation synthesized from low level informations provided by different kinds of sensors. The fusion of the collected data will result in fewer and higher level informations more easily assessed by a human operator and that will assist him effectively in his de...
computer science
19,915
Knowledge Integration for Conditional Probability Assessments
cs.AI
In the probabilistic approach to uncertainty management the input knowledge is usually represented by means of some probability distributions. In this paper we assume that the input knowledge is given by two discrete conditional probability distributions, represented by two stochastic matrices P and Q. The consistency ...
computer science
19,916
Integrating Model Construction and Evaluation
cs.AI
To date, most probabilistic reasoning systems have relied on a fixed belief network constructed at design time. The network is used by an application program as a representation of (in)dependencies in the domain. Probabilistic inference algorithms operate over the network to answer queries. Recognizing the inflexibilit...
computer science
19,917
Reasoning With Qualitative Probabilities Can Be Tractable
cs.AI
We recently described a formalism for reasoning with if-then rules that re expressed with different levels of firmness [18]. The formalism interprets these rules as extreme conditional probability statements, specifying orders of magnitude of disbelief, which impose constraints over possible rankings of worlds. It was ...
computer science
19,918
A computational scheme for Reasoning in Dynamic Probabilistic Networks
cs.AI
A computational scheme for reasoning about dynamic systems using (causal) probabilistic networks is presented. The scheme is based on the framework of Lauritzen and Spiegelhalter (1988), and may be viewed as a generalization of the inference methods of classical time-series analysis in the sense that it allows descript...
computer science
19,919
The Dynamic of Belief in the Transferable Belief Model and Specialization-Generalization Matrices
cs.AI
The fundamental updating process in the transferable belief model is related to the concept of specialization and can be described by a specialization matrix. The degree of belief in the truth of a proposition is a degree of justified support. The Principle of Minimal Commitment implies that one should never give more ...
computer science
19,920
A Note on the Measure of Discord
cs.AI
A new entropy-like measure as well as a new measure of total uncertainty pertaining to the Dempster-Shafer theory are introduced. It is argued that these measures are better justified than any of the previously proposed candidates.
computer science
19,921
Semantics for Probabilistic Inference
cs.AI
A number of writers(Joseph Halpern and Fahiem Bacchus among them) have offered semantics for formal languages in which inferences concerning probabilities can be made. Our concern is different. This paper provides a formalization of nonmonotonic inferences in which the conclusion is supported only to a certain degree. ...
computer science
19,922
Some Problems for Convex Bayesians
cs.AI
We discuss problems for convex Bayesian decision making and uncertainty representation. These include the inability to accommodate various natural and useful constraints and the possibility of an analog of the classical Dutch Book being made against an agent behaving in accordance with convex Bayesian prescriptions. A ...
computer science
19,923
Bayesian Meta-Reasoning: Determining Model Adequacy from Within a Small World
cs.AI
This paper presents a Bayesian framework for assessing the adequacy of a model without the necessity of explicitly enumerating a specific alternate model. A test statistic is developed for tracking the performance of the model across repeated problem instances. Asymptotic methods are used to derive an approximate distr...
computer science
19,924
The Bounded Bayesian
cs.AI
The ideal Bayesian agent reasons from a global probability model, but real agents are restricted to simplified models which they know to be adequate only in restricted circumstances. Very little formal theory has been developed to help fallibly rational agents manage the process of constructing and revising small world...
computer science
19,925
Representing Context-Sensitive Knowledge in a Network Formalism: A Preliminary Report
cs.AI
Automated decision making is often complicated by the complexity of the knowledge involved. Much of this complexity arises from the context sensitive variations of the underlying phenomena. We propose a framework for representing descriptive, context-sensitive knowledge. Our approach attempts to integrate categorical a...
computer science
19,926
A Probabilistic Network of Predicates
cs.AI
Bayesian networks are directed acyclic graphs representing independence relationships among a set of random variables. A random variable can be regarded as a set of exhaustive and mutually exclusive propositions. We argue that there are several drawbacks resulting from the propositional nature and acyclic structure of ...
computer science
19,927
Representing Heuristic Knowledge in D-S Theory
cs.AI
The Dempster-Shafer theory of evidence has been used intensively to deal with uncertainty in knowledge-based systems. However the representation of uncertain relationships between evidence and hypothesis groups (heuristic knowledge) is still a major research problem. This paper presents an approach to representing such...
computer science
19,928
The Topological Fusion of Bayes Nets
cs.AI
Bayes nets are relatively recent innovations. As a result, most of their theoretical development has focused on the simplest class of single-author models. The introduction of more sophisticated multiple-author settings raises a variety of interesting questions. One such question involves the nature of compromise and c...
computer science
19,929
Calculating Uncertainty Intervals From Conditional Convex Sets of Probabilities
cs.AI
In Moral, Campos (1991) and Cano, Moral, Verdegay-Lopez (1991) a new method of conditioning convex sets of probabilities has been proposed. The result of it is a convex set of non-necessarily normalized probability distributions. The normalizing factor of each probability distribution is interpreted as the possibility ...
computer science
19,930
Sensor Validation Using Dynamic Belief Networks
cs.AI
The trajectory of a robot is monitored in a restricted dynamic environment using light beam sensor data. We have a Dynamic Belief Network (DBN), based on a discrete model of the domain, which provides discrete monitoring analogous to conventional quantitative filter techniques. Sensor observations are added to the basi...
computer science
19,931
aHUGIN: A System Creating Adaptive Causal Probabilistic Networks
cs.AI
The paper describes aHUGIN, a tool for creating adaptive systems. aHUGIN is an extension of the HUGIN shell, and is based on the methods reported by Spiegelhalter and Lauritzen (1990a). The adaptive systems resulting from aHUGIN are able to adjust the C011ditional probabilities in the model. A short analysis of the ada...
computer science
19,932
MESA: Maximum Entropy by Simulated Annealing
cs.AI
Probabilistic reasoning systems combine different probabilistic rules and probabilistic facts to arrive at the desired probability values of consequences. In this paper we describe the MESA-algorithm (Maximum Entropy by Simulated Annealing) that derives a joint distribution of variables or propositions. It takes into a...
computer science
19,933
Decision Methods for Adaptive Task-Sharing in Associate Systems
cs.AI
This paper describes some results of research on associate systems: knowledge-based systems that flexibly and adaptively support their human users in carrying out complex, time-dependent problem-solving tasks under uncertainty. Based on principles derived from decision theory and decision analysis, a problem-solving ap...
computer science
19,934
Modeling Uncertain Temporal Evolutions in Model-Based Diagnosis
cs.AI
Although the notion of diagnostic problem has been extensively investigated in the context of static systems, in most practical applications the behavior of the modeled system is significantly variable during time. The goal of the paper is to propose a novel approach to the modeling of uncertainty about temporal evolut...
computer science
19,935
Guess-And-Verify Heuristics for Reducing Uncertainties in Expert Classification Systems
cs.AI
An expert classification system having statistical information about the prior probabilities of the different classes should be able to use this knowledge to reduce the amount of additional information that it must collect, e.g., through questions, in order to make a correct classification. This paper examines how best...
computer science
19,936
R&D Analyst: An Interactive Approach to Normative Decision System Model Construction
cs.AI
This paper describes the architecture of R&D Analyst, a commercial intelligent decision system for evaluating corporate research and development projects and portfolios. In analyzing projects, R&D Analyst interactively guides a user in constructing an influence diagram model for an individual research project. The syst...
computer science
19,937
Possibilistic Constraint Satisfaction Problems or "How to handle soft constraints?"
cs.AI
Many AI synthesis problems such as planning or scheduling may be modelized as constraint satisfaction problems (CSP). A CSP is typically defined as the problem of finding any consistent labeling for a fixed set of variables satisfying all given constraints between these variables. However, for many real tasks such as j...
computer science
19,938
Decision Making Using Probabilistic Inference Methods
cs.AI
The analysis of decision making under uncertainty is closely related to the analysis of probabilistic inference. Indeed, much of the research into efficient methods for probabilistic inference in expert systems has been motivated by the fundamental normative arguments of decision theory. In this paper we show how the d...
computer science
19,939
Conditional Independence in Uncertainty Theories
cs.AI
This paper introduces the notions of independence and conditional independence in valuation-based systems (VBS). VBS is an axiomatic framework capable of representing many different uncertainty calculi. We define independence and conditional independence in terms of factorization of the joint valuation. The definitions...
computer science
19,940
The Nature of the Unnormalized Beliefs Encountered in the Transferable Belief Model
cs.AI
Within the transferable belief model, positive basic belief masses can be allocated to the empty set, leading to unnormalized belief functions. The nature of these unnormalized beliefs is analyzed.
computer science
19,941
Intuitions about Ordered Beliefs Leading to Probabilistic Models
cs.AI
The general use of subjective probabilities to model belief has been justified using many axiomatic schemes. For example, ?consistent betting behavior' arguments are well-known. To those not already convinced of the unique fitness and generality of probability models, such justifications are often unconvincing. The pre...
computer science
19,942
Expressing Relational and Temporal Knowledge in Visual Probabilistic Networks
cs.AI
Bayesian networks have been used extensively in diagnostic tasks such as medicine, where they represent the dependency relations between a set of symptoms and a set of diseases. A criticism of this type of knowledge representation is that it is restricted to this kind of task, and that it cannot cope with the knowledge...
computer science
19,943
A Fuzzy Logic Approach to Target Tracking
cs.AI
This paper discusses a target tracking problem in which no dynamic mathematical model is explicitly assumed. A nonlinear filter based on the fuzzy If-then rules is developed. A comparison with a Kalman filter is made, and empirical results show that the performance of the fuzzy filter is better. Intensive simulations s...
computer science
19,944
Towards Precision of Probabilistic Bounds Propagation
cs.AI
The DUCK-calculus presented here is a recent approach to cope with probabilistic uncertainty in a sound and efficient way. Uncertain rules with bounds for probabilities and explicit conditional independences can be maintained incrementally. The basic inference mechanism relies on local bounds propagation, implementable...
computer science
19,945
An Algorithm for Deciding if a Set of Observed Independencies Has a Causal Explanation
cs.AI
In a previous paper [Pearl and Verma, 1991] we presented an algorithm for extracting causal influences from independence information, where a causal influence was defined as the existence of a directed arc in all minimal causal models consistent with the data. In this paper we address the question of deciding whether t...
computer science
19,946
Generalizing Jeffrey Conditionalization
cs.AI
Jeffrey's rule has been generalized by Wagner to the case in which new evidence bounds the possible revisions of a prior probability below by a Dempsterian lower probability. Classical probability kinematics arises within this generalization as the special case in which the evidentiary focal elements of the bounding lo...
computer science
19,947
Interval Structure: A Framework for Representing Uncertain Information
cs.AI
In this paper, a unified framework for representing uncertain information based on the notion of an interval structure is proposed. It is shown that the lower and upper approximations of the rough-set model, the lower and upper bounds of incidence calculus, and the belief and plausibility functions all obey the axioms ...
computer science
19,948
Exploring Localization in Bayesian Networks for Large Expert Systems
cs.AI
Current Bayesian net representations do not consider structure in the domain and include all variables in a homogeneous network. At any time, a human reasoner in a large domain may direct his attention to only one of a number of natural subdomains, i.e., there is ?localization' of queries and evidence. In such a case, ...
computer science
19,949
A Decision Calculus for Belief Functions in Valuation-Based Systems
cs.AI
Valuation-based system (VBS) provides a general framework for representing knowledge and drawing inferences under uncertainty. Recent studies have shown that the semantics of VBS can represent and solve Bayesian decision problems (Shenoy, 1991a). The purpose of this paper is to propose a decision calculus for Dempster-...
computer science
19,950
Sidestepping the Triangulation Problem in Bayesian Net Computations
cs.AI
This paper presents a new approach for computing posterior probabilities in Bayesian nets, which sidesteps the triangulation problem. The current state of art is the clique tree propagation approach. When the underlying graph of a Bayesian net is triangulated, this approach arranges its cliques into a tree and computes...
computer science
19,951
Viterbi training in PRISM
cs.AI
VT (Viterbi training), or hard EM, is an efficient way of parameter learning for probabilistic models with hidden variables. Given an observation $y$, it searches for a state of hidden variables $x$ that maximizes $p(x,y \mid \theta)$ by coordinate ascent on parameters $\theta$ and $x$. In this paper we introduce VT to...
computer science
19,952
"Conditional Inter-Causally Independent" Node Distributions, a Property of "Noisy-Or" Models
cs.AI
This paper examines the interdependence generated between two parent nodes with a common instantiated child node, such as two hypotheses sharing common evidence. The relation so generated has been termed "intercausal." It is shown by construction that inter-causal independence is possible for binary distributions at on...
computer science
19,953
Combining Multiple-Valued Logics in Modular Expert Systems
cs.AI
The way experts manage uncertainty usually changes depending on the task they are performing. This fact has lead us to consider the problem of communicating modules (task implementations) in a large and structured knowledge based system when modules have different uncertainty calculi. In this paper, the analysis of the...
computer science
19,954
Constraint Propagation with Imprecise Conditional Probabilities
cs.AI
An approach to reasoning with default rules where the proportion of exceptions, or more generally the probability of encountering an exception, can be at least roughly assessed is presented. It is based on local uncertainty propagation rules which provide the best bracketing of a conditional probability of interest fro...
computer science
19,955
Some Properties of Plausible Reasoning
cs.AI
This paper presents a plausible reasoning system to illustrate some broad issues in knowledge representation: dualities between different reasoning forms, the difficulty of unifying complementary reasoning styles, and the approximate nature of plausible reasoning. These issues have a common underlying theme: there shou...
computer science
19,956
Theory Refinement on Bayesian Networks
cs.AI
Theory refinement is the task of updating a domain theory in the light of new cases, to be done automatically or with some expert assistance. The problem of theory refinement under uncertainty is reviewed here in the context of Bayesian statistics, a theory of belief revision. The problem is reduced to an incremental l...
computer science
19,957
Combination of Upper and Lower Probabilities
cs.AI
In this paper, we consider several types of information and methods of combination associated with incomplete probabilistic systems. We discriminate between 'a priori' and evidential information. The former one is a description of the whole population, the latest is a restriction based on observations for a particular ...
computer science
19,958
A Probabilistic Analysis of Marker-Passing Techniques for Plan-Recognition
cs.AI
Useless paths are a chronic problem for marker-passing techniques. We use a probabilistic analysis to justify a method for quickly identifying and rejecting useless paths. Using the same analysis, we identify key conditions and assumptions necessary for marker-passing to perform well.
computer science
19,959
Symbolic Probabilistic Inference with Continuous Variables
cs.AI
Research on Symbolic Probabilistic Inference (SPI) [2, 3] has provided an algorithm for resolving general queries in Bayesian networks. SPI applies the concept of dependency directed backward search to probabilistic inference, and is incremental with respect to both queries and observations. Unlike traditional Bayesian...
computer science
19,960
Symbolic Probabilistic Inference with Evidence Potential
cs.AI
Recent research on the Symbolic Probabilistic Inference (SPI) algorithm[2] has focused attention on the importance of resolving general queries in Bayesian networks. SPI applies the concept of dependency-directed backward search to probabilistic inference, and is incremental with respect to both queries and observation...
computer science
19,961
A Bayesian Method for Constructing Bayesian Belief Networks from Databases
cs.AI
This paper presents a Bayesian method for constructing Bayesian belief networks from a database of cases. Potential applications include computer-assisted hypothesis testing, automated scientific discovery, and automated construction of probabilistic expert systems. Results are presented of a preliminary evaluation of ...
computer science
19,962
Local Expression Languages for Probabilistic Dependence: a Preliminary Report
cs.AI
We present a generalization of the local expression language used in the Symbolic Probabilistic Inference (SPI) approach to inference in belief nets [1l, [8]. The local expression language in SPI is the language in which the dependence of a node on its antecedents is described. The original language represented the dep...
computer science
19,963
Symbolic Decision Theory and Autonomous Systems
cs.AI
The ability to reason under uncertainty and with incomplete information is a fundamental requirement of decision support technology. In this paper we argue that the concentration on theoretical techniques for the evaluation and selection of decision options has distracted attention from many of the wider issues in deci...
computer science
19,964
A Reason Maintenace System Dealing with Vague Data
cs.AI
A reason maintenance system which extends an ATMS through Mukaidono's fuzzy logic is described. It supports a problem solver in situations affected by incomplete information and vague data, by allowing nonmonotonic inferences and the revision of previous conclusions when contradictions are detected.
computer science
19,965
Advances in Probabilistic Reasoning
cs.AI
This paper discuses multiple Bayesian networks representation paradigms for encoding asymmetric independence assertions. We offer three contributions: (1) an inference mechanism that makes explicit use of asymmetric independence to speed up computations, (2) a simplified definition of similarity networks and extensions...
computer science
19,966
Probability Estimation in Face of Irrelevant Information
cs.AI
In this paper, we consider one aspect of the problem of applying decision theory to the design of agents that learn how to make decisions under uncertainty. This aspect concerns how an agent can estimate probabilities for the possible states of the world, given that it only makes limited observations before committing ...
computer science
19,967
An Approximate Nonmyopic Computation for Value of Information
cs.AI
Value-of-information analyses provide a straightforward means for selecting the best next observation to make, and for determining whether it is better to gather additional information or to act immediately. Determining the next best test to perform, given a state of uncertainty about the world, requires a consideratio...
computer science
19,968
Search-based Methods to Bound Diagnostic Probabilities in Very Large Belief Nets
cs.AI
Since exact probabilistic inference is intractable in general for large multiply connected belief nets, approximate methods are required. A promising approach is to use heuristic search among hypotheses (instantiations of the network) to find the most probable ones, as in the TopN algorithm. Search is based on the rela...
computer science
19,969
Time-Dependent Utility and Action Under Uncertainty
cs.AI
We discuss representing and reasoning with knowledge about the time-dependent utility of an agent's actions. Time-dependent utility plays a crucial role in the interaction between computation and action under bounded resources. We present a semantics for time-dependent utility and describe the use of time-dependent inf...
computer science
19,970
Non-monotonic Reasoning and the Reversibility of Belief Change
cs.AI
Traditional approaches to non-monotonic reasoning fail to satisfy a number of plausible axioms for belief revision and suffer from conceptual difficulties as well. Recent work on ranked preferential models (RPMs) promises to overcome some of these difficulties. Here we show that RPMs are not adequate to handle iterated...
computer science
19,971
Belief and Surprise - A Belief-Function Formulation
cs.AI
We motivate and describe a theory of belief in this paper. This theory is developed with the following view of human belief in mind. Consider the belief that an event E will occur (or has occurred or is occurring). An agent either entertains this belief or does not entertain this belief (i.e., there is no "grade" in en...
computer science
19,972
Evidential Reasoning in a Categorial Perspective: Conjunction and Disjunction of Belief Functions
cs.AI
The categorial approach to evidential reasoning can be seen as a combination of the probability kinematics approach of Richard Jeffrey (1965) and the maximum (cross-) entropy inference approach of E. T. Jaynes (1957). As a consequence of that viewpoint, it is well known that category theory provides natural definitions...
computer science
19,973
Reasoning with Mass Distributions
cs.AI
The concept of movable evidence masses that flow from supersets to subsets as specified by experts represents a suitable framework for reasoning under uncertainty. The mass flow is controlled by specialization matrices. New evidence is integrated into the frame of discernment by conditioning or revision (Dempster's rul...
computer science
19,974
Conflict and Surprise: Heuristics for Model Revision
cs.AI
Any probabilistic model of a problem is based on assumptions which, if violated, invalidate the model. Users of probability based decision aids need to be alerted when cases arise that are not covered by the aid's model. Diagnosis of model failure is also necessary to control dynamic model construction and revision. Th...
computer science
19,975
Reasoning under Uncertainty: Some Monte Carlo Results
cs.AI
A series of monte carlo studies were performed to compare the behavior of some alternative procedures for reasoning under uncertainty. The behavior of several Bayesian, linear model and default reasoning procedures were examined in the context of increasing levels of calibration error. The most interesting result is th...
computer science
19,976
Representation Requirements for Supporting Decision Model Formulation
cs.AI
This paper outlines a methodology for analyzing the representational support for knowledge-based decision-modeling in a broad domain. A relevant set of inference patterns and knowledge types are identified. By comparing the analysis results to existing representations, some insights are gained into a design approach fo...
computer science
19,977
A Language for Planning with Statistics
cs.AI
When a planner must decide whether it has enough evidence to make a decision based on probability, it faces the sample size problem. Current planners using probabilities need not deal with this problem because they do not generate their probabilities from observations. This paper presents an event based language in whi...
computer science
19,978
A Modification to Evidential Probability
cs.AI
Selecting the right reference class and the right interval when faced with conflicting candidates and no possibility of establishing subset style dominance has been a problem for Kyburg's Evidential Probability system. Various methods have been proposed by Loui and Kyburg to solve this problem in a way that is both int...
computer science
19,979
Investigation of Variances in Belief Networks
cs.AI
The belief network is a well-known graphical structure for representing independences in a joint probability distribution. The methods, which perform probabilistic inference in belief networks, often treat the conditional probabilities which are stored in the network as certain values. However, if one takes either a su...
computer science
19,980
A Sensitivity Analysis of Pathfinder: A Follow-up Study
cs.AI
At last year?s Uncertainty in AI Conference, we reported the results of a sensitivity analysis study of Pathfinder. Our findings were quite unexpected-slight variations to Pathfinder?s parameters appeared to lead to substantial degradations in system performance. A careful look at our first analysis, together with the ...
computer science
19,981
Non-monotonic Negation in Probabilistic Deductive Databases
cs.AI
In this paper we study the uses and the semantics of non-monotonic negation in probabilistic deductive data bases. Based on the stable semantics for classical logic programming, we introduce the notion of stable formula, functions. We show that stable formula, functions are minimal fixpoints of operators associated wit...
computer science
19,982
Management of Uncertainty in the Multi-Level Monitoring and Diagnosis of the Time of Flight Scintillation Array
cs.AI
We present a general architecture for the monitoring and diagnosis of large scale sensor-based systems with real time diagnostic constraints. This architecture is multileveled, combining a single monitoring level based on statistical methods with two model based diagnostic levels. At each level, sources of uncertainty ...
computer science
19,983
Integrating Probabilistic Rules into Neural Networks: A Stochastic EM Learning Algorithm
cs.AI
The EM-algorithm is a general procedure to get maximum likelihood estimates if part of the observations on the variables of a network are missing. In this paper a stochastic version of the algorithm is adapted to probabilistic neural networks describing the associative dependency of variables. These networks have a pro...
computer science
19,984
Representing Bayesian Networks within Probabilistic Horn Abduction
cs.AI
This paper presents a simple framework for Horn clause abduction, with probabilities associated with hypotheses. It is shown how this representation can represent any probabilistic knowledge representable in a Bayesian belief network. The main contributions are in finding a relationship between logical and probabilisti...
computer science
19,985
Dynamic Network Updating Techniques For Diagnostic Reasoning
cs.AI
A new probabilistic network construction system, DYNASTY, is proposed for diagnostic reasoning given variables whose probabilities change over time. Diagnostic reasoning is formulated as a sequential stochastic process, and is modeled using influence diagrams. Given a set O of observations, DYNASTY creates an influence...
computer science
19,986
High Level Path Planning with Uncertainty
cs.AI
For high level path planning, environments are usually modeled as distance graphs, and path planning problems are reduced to computing the shortest path in distance graphs. One major drawback of this modeling is the inability to model uncertainties, which are often encountered in practice. In this paper, a new tool, ca...
computer science
19,987
Formal Model of Uncertainty for Possibilistic Rules
cs.AI
Given a universe of discourse X-a domain of possible outcomes-an experiment may consist of selecting one of its elements, subject to the operation of chance, or of observing the elements, subject to imprecision. A priori uncertainty about the actual result of the experiment may be quantified, representing either the li...
computer science
19,988
Deliberation and its Role in the Formation of Intentions
cs.AI
Deliberation plays an important role in the design of rational agents embedded in the real-world. In particular, deliberation leads to the formation of intentions, i.e., plans of action that the agent is committed to achieving. In this paper, we present a branching time possible-worlds model for representing and reason...
computer science
19,989
Handling Uncertainty during Plan Recognition in Task-Oriented Consultation Systems
cs.AI
During interactions with human consultants, people are used to providing partial and/or inaccurate information, and still be understood and assisted. We attempt to emulate this capability of human consultants; in computer consultation systems. In this paper, we present a mechanism for handling uncertainty in plan recog...
computer science
19,990
Truth as Utility: A Conceptual Synthesis
cs.AI
This paper introduces conceptual relations that synthesize utilitarian and logical concepts, extending the logics of preference of Rescher. We define first, in the context of a possible worlds model, constraint-dependent measures that quantify the relative quality of alternative solutions of reasoning problems or the r...
computer science
19,991
Pulcinella: A General Tool for Propagating Uncertainty in Valuation Networks
cs.AI
We present PULCinella and its use in comparing uncertainty theories. PULCinella is a general tool for Propagating Uncertainty based on the Local Computation technique of Shafer and Shenoy. It may be specialized to different uncertainty theories: at the moment, Pulcinella can propagate probabilities, belief functions, B...
computer science
19,992
Structuring Bodies of Evidence
cs.AI
In this article we present two ways of structuring bodies of evidence, which allow us to reduce the complexity of the operations usually performed in the framework of evidence theory. The first structure just partitions the focal elements in a body of evidence by their cardinality. With this structure we are able to re...
computer science
19,993
On the Generation of Alternative Explanations with Implications for Belief Revision
cs.AI
In general, the best explanation for a given observation makes no promises on how good it is with respect to other alternative explanations. A major deficiency of message-passing schemes for belief revision in Bayesian networks is their inability to generate alternatives beyond the second best. In this paper, we presen...
computer science
19,994
Completing Knowledge by Competing Hierarchies
cs.AI
A control strategy for expert systems is presented which is based on Shafer's Belief theory and the combination rule of Dempster. In contrast to well known strategies it is not sequentially and hypotheses-driven, but parallel and self organizing, determined by the concept of information gain. The information gain, calc...
computer science
19,995
A Graph-Based Inference Method for Conditional Independence
cs.AI
The graphoid axioms for conditional independence, originally described by Dawid [1979], are fundamental to probabilistic reasoning [Pearl, 19881. Such axioms provide a mechanism for manipulating conditional independence assertions without resorting to their numerical definition. This paper explores a representation for...
computer science
19,996
A Fusion Algorithm for Solving Bayesian Decision Problems
cs.AI
This paper proposes a new method for solving Bayesian decision problems. The method consists of representing a Bayesian decision problem as a valuation-based system and applying a fusion algorithm for solving it. The fusion algorithm is a hybrid of local computational methods for computation of marginals of joint proba...
computer science
19,997
Algorithms for Irrelevance-Based Partial MAPs
cs.AI
Irrelevance-based partial MAPs are useful constructs for domain-independent explanation using belief networks. We look at two definitions for such partial MAPs, and prove important properties that are useful in designing algorithms for computing them effectively. We make use of these properties in modifying our standar...
computer science
19,998
About Updating
cs.AI
Survey of several forms of updating, with a practical illustrative example. We study several updating (conditioning) schemes that emerge naturally from a common scenarion to provide some insights into their meaning. Updating is a subtle operation and there is no single method, no single 'good' rule. The choice of the a...
computer science
19,999
Compressed Constraints in Probabilistic Logic and Their Revision
cs.AI
In probabilistic logic entailments, even moderate size problems can yield linear constraint systems with so many variables that exact methods are impractical. This difficulty can be remedied in many cases of interest by introducing a three valued logic (true, false, and "don't care"). The three-valued approach allows t...
computer science
20,000
Balancing bike sharing systems (BBSS): instance generation from the CitiBike NYC data
cs.AI
Bike sharing systems are a very popular means to provide bikes to citizens in a simple and cheap way. The idea is to install bike stations at various points in the city, from which a registered user can easily loan a bike by removing it from a specialized rack. After the ride, the user may return the bike at any statio...
computer science
20,001
Dependence space of matroids and its application to attribute reduction
cs.AI
Attribute reduction is a basic issue in knowledge representation and data mining. Rough sets provide a theoretical foundation for the issue. Matroids generalized from matrices have been widely used in many fields, particularly greedy algorithm design, which plays an important role in attribute reduction. Therefore, it ...
computer science