摘要:

Intrusion‐detection systems (IDS) have been used as part of the security of information and communication technologies infrastructure because it is difficult to ensure that information systems are free from security flaws. In this paper we present a new design of an anomaly IDS. Design and development of the IDS are considered in our 3 main stages: normal behavior construction, anomaly detection and model update. A parametrical mixture model is used for behavior modeling from reference data. The associated Bayesian classification leads to the detection algorithm. A continuous model parameter re‐estimation is discussed as a possible heuristic for model update. Real‐time requirements are presented. Detection and update algorithms for the special case of Gaussian parametrical model are designed and evaluated with respect to their real‐time features in a PC‐like platform without any special hardware requirements. Experiments validating the model are presented as well. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570541

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The goal of Bayesian pattern classification is to state the probability that an object belongs to a particular class given observed values of attributes of the object. Recent research in this area has centered on the use of either mixture models or kernel‐based methods, such as Support Vector Machines and Relevance Vector Machines. We review this research and show how these areas are related to each other. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570542

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A Markov Chain Monte Carlo (MCMC) procedure is presented for the identification of clutter in weather‐radar images. The key attributes of the image are the spatial coherence of the areas of clutter (noise) and cloud and the high spatial autocorrelation of the values in areas of cloud. A form of simulated annealing provides the possibility of fast clutter removal. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570543

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A procedure based on the combination of a Bayesian changepoint model and ordinary least squares is used to identify and quantify regions where a radar signal has been attenuated (i.e.diminished) as a consequence of intervening weather. A graphical polar display is introduced that illustrates the location and importance of the attenuation. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570544

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

In this paper, we consider the problem of blind signal and image separation using a sparse representation of the images in the wavelet domain. We consider the problem in a Bayesian estimation framework using the fact that the distribution of the wavelet coefficients of real world images can naturally be modeled by an exponential power probability density function. The Bayesian approach which has been used with success in blind source separation gives also the possibility of including any prior information we may have on the mixing matrix elements as well as on the hyperparameters (parameters of the prior laws of the noise and the sources). We consider two cases: first the case where the wavelet coefficients are assumed to be i.i.d. and second the case where we model the correlation between the coefficients of two adjacent scales by a first order Markov chain. This paper only reports on the first case, the second case results will be reported in a near future The estimation computations are done via a Monte Carlo Markov Chain (MCMC) procedure. Some simulations show the performances of the proposed method. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570545

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A given question can be defined in terms of the set of statements or assertions that answer it. Application of logical inference to these sets of assertions allows one to derive the logic of inquiry among questions. There are interesting symmetries between the logics of inference and inquiry; where probability describes the degree to which a premise implies an assertion, there exists an analogous measure that describes the bearing or relevance that a question has on an outstanding issue. These have been extended to suggest that the logic of inquiry results in functional relationships analogous to, although more general than, those found in information theory. Employing lattice theory, I examine in greater detail the structure of the space of assertions and questions demonstrating that the symmetries between the logical relations in each of the spaces derive directly from the lattice structure. Furthermore, I show that while symmetries between the spaces exist, the two lattices are not isomorphic. The lattice of assertions is described by a Boolean lattice 2N, whereas the lattice of assuredly real questions is shown to be a sublattice of the free distributive latticeFD(N) = 22N. Thus there does not exist a one‐to‐one mapping of assertions to questions, there is no reflection symmetry between the two spaces, and questions in general do not possess complements. Last, with these lattice structures in mind, I discuss the relationship between probability, relevance, and entropy. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570546

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

This paper proposes a framework for quantifying logical and geometric inquiry through specific interpretations of Bayes’ Theorem and Information Theory. In logical inquiry there are a countable number of possible discrete answers that define the inquiry, and Bayes’ Theorem serves to move the observer posing the question along a trajectory in a hyberbolic figure in a manner suggested by Rodriguez. ForN=3, this plane is a hyperbolic triangle whose angles sum to zero — the smallest possible value in the hyperbolic plane where the sum of the angles of a triangle must sum to a positive number less than pi. In euclidean space, the hyberbolic figure becomes a multi‐dimensional simplex or polyhedron described by Shannon in his paper on a geometrical perspective of channel capacity. A theory of geometric inquiry requires that one consider an observer who conjointly possesses an objective reality space &THgr; and a physical or measurable spaceX. It is discussed how the matching of these spaces characterizes the ability of an observer to distinguish its posited objective reality. A simple functional formIis suggested as a measure of the degree of distinguishability for an observer. This form corresponds to the trace of the Fisher information matrix ofp(x|&thgr;) over &thgr;∈ &THgr;. The origin and precise specification of the requirements that give rise to the specified functional form are unknown and represents an important area of future study with clues suggested in the work of Balasubramanian. At the same time, the question is asked regarding the nature of the metrics and probability distributions arising when an observer balances prior ignorance and prior knowledge through the extremizing of a functionalJ(p,∇p) =I+ &lgr;Hover probability densitiesp. The functionalIis thea prioriability of the observer to distinguish pure space,His the prior ignorance of the same observer over the same space, and &lgr; is a scalar Lagrange multiplier ostensibly needed to balance units, but having additional interesting properties. Explicit solutions are derived for optimalpin both one and in general inNdimensions for &lgr; = 0 and &lgr; ≠ 0. In particular, the distributions that result when &lgr; ≠ 0 include gaussian densities satisfying the functional form of distributions defining the elements of the Fisher Information matrix of pure‐space as discussed by Rodriguez which possesses negative curvature when spatial uncertainty exists. Although only inquiry is discussed, a formalized conjoint theory of inquiry and control has significant implications regarding the engineering and design of intelligent systems that operate cybernetically. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570547

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

During the MaxEnt 2002 workshop in Moscow, Idaho, Tony Vignaux asked again a few simple questions about using Maximum Entropy or Bayesian approaches for the famous Dice problems which have been analyzed many times through this workshop and also in other places. Here, there is another analysis of these problems. I hope that, this paper will answer a few questions of Tony and other participants of the workshop on the situations where we can use Maximum Entropy or Bayesian approaches or even the cases where we can actually use both of them. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570548

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

In this contribution, we study the problem of prior selection arising in Bayesian inference. There is an extensive literature on the construction of non informative priors and the subject seems far from a definite solution [1]. Here we revisit this subject with differential geometry tools and propose to construct the prior in a Bayesian decision theoretic framework. We show how the construction of a prior by projection is the best way to take into account the restriction to a particular family of parametric models. For instance, we apply this procedure to the curved parametric families where the ignorance is directly expressed by the relative geometry of the restricted model in the wider model containing it. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570549

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A fundamental step in decision analysis is the elicitation of the decision‐maker’s preferences about the prospects of a decision situation in the form of utility values. However, this can be a difficult task to perform in practice as the number of prospects may be large, and eliciting a utility value for each prospect may be a time consuming and stressful task for the decision maker. To relieve some of the burden of this task, this paper presents a normative method to assign unbiased utility values when only incomplete preference information is available about the decision maker. We introduce the notion of a utility density function and propose a maximum entropy utility principle for utility assignment. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1570550

出版商:AIP    

年代:1903

数据来源: AIP