143,996 research outputs found
On Fusion Algebras and Modular Matrices
We consider the fusion algebras arising in e.g. Wess-Zumino-Witten conformal
field theories, affine Kac-Moody algebras at positive integer level, and
quantum groups at roots of unity. Using properties of the modular matrix ,
we find small sets of primary fields (equivalently, sets of highest weights)
which can be identified with the variables of a polynomial realization of the
fusion algebra at level . We prove that for many choices of rank
and level , the number of these variables is the minimum possible, and we
conjecture that it is in fact minimal for most and . We also find new,
systematic sources of zeros in the modular matrix . In addition, we obtain a
formula relating the entries of at fixed points, to entries of at
smaller ranks and levels. Finally, we identify the number fields generated over
the rationals by the entries of , and by the fusion (Verlinde) eigenvalues.Comment: 28 pages, plain Te
Signal-Level Information Fusion for Less Constrained Iris Recognition using Sparse-Error Low Rank Matrix Factorization
Iris recognition systems working in less constrained environments with the subject at-a-distance and on-the-move suffer from the noise and degradations in the iris captures. These noise and degradations significantly deteriorate iris recognition performance. In this paper, we propose a novel signal-level information fusion method to mitigate the influence of noise and degradations for less constrained iris recognition systems. The proposed method is based on low rank approximation (LRA). Given multiple noisy captures of the same eye, we assume that: 1) the potential noiseless images lie in a low rank subspace and 2) the noise is spatially sparse. Based on these assumptions, we seek an LRA of noisy captures to separate the noiseless images and noise for information fusion. Specifically, we propose a sparse-error low rank matrix factorization model to perform LRA, decomposing the noisy captures into a low rank component and a sparse error component. The low rank component estimates the potential noiseless images, while the error component models the noise. Then, the low rank and error components are utilized to perform signal-level fusion separately, producing two individually fused images. Finally, we combine the two fused images at the code level to produce one iris code as the final fusion result. Experiments on benchmark data sets demonstrate that the proposed signal-level fusion method is able to achieve a generally improved iris recognition performance in less constrained environment, in comparison with the existing iris recognition algorithms, especially for the iris captures with heavy noise and low quality
Superconformal Coset Equivalence from Level-Rank Duality
We construct a one-to-one map between the primary fields of the N=2
superconformal Kazama-Suzuki models G(m,n,k) and G(k,n,m) based on complex
Grassmannian cosets, using level-rank duality of Wess-Zumino-Witten models. We
then show that conformal weights, superconformal U(1) charges, modular
transformation matrices, and fusion rules are preserved under this map,
providing strong evidence for the equivalence of these coset models.Comment: 25 pages, harvmac, no figures, added referenc
Segmentation-level fusion for iris recognition
This paper investigates the potential of fusion at normalisation/segmentation level prior to feature extraction. While there are several biometric fusion methods at data/feature level, score level and rank/decision level combining raw biometric signals, scores, or ranks/decisions, this type of fusion is still in its infancy. However, the increasing demand to allow for more relaxed and less invasive recording conditions, especially for on-the-move iris recognition, suggests to further investigate fusion at this very low level. This paper focuses on the approach of multi-segmentation fusion for iris biometric systems investigating the benefit of combining the segmentation result of multiple normalisation algorithms, using four methods from two different public iris toolkits (USIT, OSIRIS) on the public CASIA and IITD iris datasets. Evaluations based on recognition accuracy and ground truth segmentation data indicate high sensitivity with regards to the type of errors made by segmentation algorithms
Detection-by-Localization: Maintenance-Free Change Object Detector
Recent researches demonstrate that self-localization performance is a very
useful measure of likelihood-of-change (LoC) for change detection. In this
paper, this "detection-by-localization" scheme is studied in a novel
generalized task of object-level change detection. In our framework, a given
query image is segmented into object-level subimages (termed "scene parts"),
which are then converted to subimage-level pixel-wise LoC maps via the
detection-by-localization scheme. Our approach models a self-localization
system as a ranking function, outputting a ranked list of reference images,
without requiring relevance score. Thanks to this new setting, we can
generalize our approach to a broad class of self-localization systems. Our
ranking based self-localization model allows to fuse self-localization results
from different modalities via an unsupervised rank fusion derived from a field
of multi-modal information retrieval (MMR).Comment: 7 pages, 3 figures, Technical repor
Robust multi-modal and multi-unit feature level fusion of face and iris biometrics
Multi-biometrics has recently emerged as a mean of more robust and effcient
personal verification and identification. Exploiting information from multiple
sources at various levels i.e., feature, score, rank or decision, the false acceptance
and rejection rates can be considerably reduced. Among all, feature level fusion
is relatively an understudied problem. This paper addresses the feature level
fusion for multi-modal and multi-unit sources of information. For multi-modal
fusion the face and iris biometric traits are considered, while the multi-unit fusion
is applied to merge the data from the left and right iris images. The proposed
approach computes the SIFT features from both biometric sources, either multi-
modal or multi-unit. For each source, the extracted SIFT features are selected via
spatial sampling. Then these selected features are finally concatenated together
into a single feature super-vector using serial fusion. This concatenated feature
vector is used to perform classification.
Experimental results from face and iris standard biometric databases are
presented. The reported results clearly show the performance improvements in
classification obtained by applying feature level fusion for both multi-modal and
multi-unit biometrics in comparison to uni-modal classification and score level
fusion
Learning to Rank Academic Experts in the DBLP Dataset
Expert finding is an information retrieval task that is concerned with the
search for the most knowledgeable people with respect to a specific topic, and
the search is based on documents that describe people's activities. The task
involves taking a user query as input and returning a list of people who are
sorted by their level of expertise with respect to the user query. Despite
recent interest in the area, the current state-of-the-art techniques lack in
principled approaches for optimally combining different sources of evidence.
This article proposes two frameworks for combining multiple estimators of
expertise. These estimators are derived from textual contents, from
graph-structure of the citation patterns for the community of experts, and from
profile information about the experts. More specifically, this article explores
the use of supervised learning to rank methods, as well as rank aggregation
approaches, for combing all of the estimators of expertise. Several supervised
learning algorithms, which are representative of the pointwise, pairwise and
listwise approaches, were tested, and various state-of-the-art data fusion
techniques were also explored for the rank aggregation framework. Experiments
that were performed on a dataset of academic publications from the Computer
Science domain attest the adequacy of the proposed approaches.Comment: Expert Systems, 2013. arXiv admin note: text overlap with
arXiv:1302.041
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