Security issues are crucial in a number of machine learning applications, especially in scenarios dealing with human activity rather than natural phenomena (e.g., information ranking, spam detection, malware detection...
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Security issues are crucial in a number of machine learning applications, especially in scenarios dealing with human activity rather than natural phenomena (e.g., information ranking, spam detection, malware detection, etc.). In such cases, learning algorithms may have to cope with manipulated data aimed at hampering decision making. Although some previous work addressed the issue of handling malicious data in the context of supervised learning, very little is known about the behavior of anomaly detection methods in such scenarios. In this contribution, we analyze the performance of a particular method--online centroid anomaly detection--in the presence of adversarial noise. Our analysis addresses the following security-related issues: formalization of learning and attack processes, derivation of an optimal attack, and analysis of attack efficiency and limitations. We derive bounds on the effectiveness of a poisoning attack against centroid anomaly detection under different conditions: attacker's full or limited control over the traffic and bounded false positive rate. Our bounds show that whereas a poisoning attack can be effectively staged in the unconstrained case, it can be made arbitrarily difficult (a strict upper bound on the attacker's gain) if external constraints are properly used. Our experimental evaluation, carried out on real traces of HTTP and exploit traffic, confirms the tightness of our theoretical bounds and the practicality of our protection mechanisms.
We propose a novel algebraic algorithmic framework for dealing with probability distributions represented by their cumulants such as the mean and covariance matrix. As an example, we consider the unsupervised learning...
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We propose a novel algebraic algorithmic framework for dealing with probability distributions represented by their cumulants such as the mean and covariance matrix. As an example, we consider the unsupervised learning problem of finding the subspace on which several probability distributions agree. Instead of minimizing an objective function involving the estimated cumulants, we show that by treating the cumulants as elements of the polynomial ring we can directly solve the problem, at a lower computational cost and with higher accuracy. Moreover, the algebraic viewpoint on probability distributions allows us to invoke the theory of algebraic geometry, which we demonstrate in a compact proof for an identifiability criterion.
Latent fingerprints, or simply latents, have been considered as cardinal evidence for identifying and convicting criminals. The amount of information available for identification from latents is often limited due to t...
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Recognizing Event-Related Desynchronization or Synchronization (ERD/ERS) patterns generated by motor imagery tasks is an important process in brain-computer interfaces (BCI). One of the most well-known algorithms to e...
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ISBN:
(纸本)9781457701221
Recognizing Event-Related Desynchronization or Synchronization (ERD/ERS) patterns generated by motor imagery tasks is an important process in brain-computer interfaces (BCI). One of the most well-known algorithms to extract the discriminative patterns is Common Spatial Patterns (CSP). It finds an optimal spatial filter considering the spatial distribution of the ERD/ERS patterns. The CSP algorithm, however, does not consider temporal information of the Electroencephalogram (EEG) signals even though EEG signals are naturally non-stationary. In order to circumvent the limitation, in this paper, we propose a novel method, Time- Dependent Common Spatial Patterns (TDCSP) to classify multiclass motor imagery tasks. We optimize CSP filters in multiple local time ranges of EEG signals individually based on statistical analysis to effectively reflect changes of discriminative spatial distributions over time. We evaluated the proposed method by experiments on BCI Competition IV dataset 2-a, which resulted in high performance outperforming the previous methods in the literature.
A new learning algorithm for categorical data, named CRN (Classification by Rule-based Neighbors) is proposed in this paper. CRN is a nonmetric and parameter-free classifier, and can be regarded as a hybrid of rule in...
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ISBN:
(纸本)9781457720758
A new learning algorithm for categorical data, named CRN (Classification by Rule-based Neighbors) is proposed in this paper. CRN is a nonmetric and parameter-free classifier, and can be regarded as a hybrid of rule induction and instance-based learning. Based on a new measure of attributes quality and the separate-and-conquer strategy, CRN learns a collection of feature sets such that for each pair of instances belonging to different classes, there is a feature set on which the two instances disagree. For an unlabeled instance I and a labeled instance I', I' is a neighbor of I if and only if they agree on all attributes of a feature set. Then, CRN classifies an unlabeled instance I based on I's neighbors on those learned feature sets. To validate the performance of CRN, CRN is compared with six state-of-the-art classifiers on twenty-four datasets. Experimental results demonstrate that although the underlying idea of CRN is simple, the predictive accuracy of CRN is comparable to or better than that of the state-of-the-art classifiers on most datasets.
We propose an algorithm for the visual detection and localisation of the hand of a humanoid robot. This algorithm imposes low requirements on the type of supervision required to achieve good performance. In particular...
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We propose an algorithm for the visual detection and localisation of the hand of a humanoid robot. This algorithm imposes low requirements on the type of supervision required to achieve good performance. In particular the system performs feature selection and adaptation using images that are only labelled as containing the hand or not, without any explicit segmentation. Our algorithm is an online variant of Multiple Instance Learning based on boosting. Experiments in real-world conditions on the iCub humanoid robot confirm that the algorithm can learn the visual appearance of the hand, reaching an accuracy comparable with its off-line version. This remains true when supervision is generated by the robot itself in a completely autonomous fashion. Algorithms with weak supervision requirements like the one we describe are useful for autonomous robots that learn and adapt online to a changing environment. The algorithm is not hand-specific and could be easily applied to wide range of problems involving visual recognition of generic objects.
Identifying suspects based on impressions of fingers lifted from crime scenes (latent prints) is extremely important to law enforcement agencies. Latents are usually partial fingerprints with small area, contain nonli...
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Touchless 3D fingerprint sensors can capture both 3D depth information and albedo images of the finger surface. Compared with 2D fingerprint images acquired by traditional contact-based fingerprint sensors, the 3D fin...
Abstract This paper presents a complete set of methods for the performance analysis and design of closed loop systems with nonlinear actuators and sensors (so-called Linear Plant/Nonlinear Instrumentation, or LPNI, sy...
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Abstract This paper presents a complete set of methods for the performance analysis and design of closed loop systems with nonlinear actuators and sensors (so-called Linear Plant/Nonlinear Instrumentation, or LPNI, systems). As it turns out, these methods are quite similar to those in the linear case. Accordingly, the resulting methods are referred to as Quasilinear Control (QLC) Theory. Since the main analysis and design techniques of QLC are not too different from the well known linear control-theoretic methods, QLC can be viewed as a simple addition to the standard toolbox of control engineering practitioners and students alike.
The selection of image fusion techniques has always been a compromise between effectiveness and efficiency. In this paper, foveation (using log-polar transformation) is introduced to satisfy the real-time requirement ...
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The selection of image fusion techniques has always been a compromise between effectiveness and efficiency. In this paper, foveation (using log-polar transformation) is introduced to satisfy the real-time requirement of applications where the fused image is eventually presented to a human to interpret. Log-polar transformation achieves a data reduction without a subsequent loss in perceptual information. Thus, it can be used to reduce the execution time of any existing image fusion technique without modifying the technique itself. In this paper, the log-polar transformation is integrated with three widely-used image fusion techniques: image averaging, the Laplacian pyramid, and the Discrete Wavelet Transform. Then, the proposed fusion process is objectively evaluated using a set of established metrics; they are Mutual Information (MI), Xydas & Petrovic (Q AB/F ), and Piella & Heijmans (Q w ).
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