Anomalous pattern based clustering of mental tasks with subject independent learning – some preliminary results

In this paper we describe a new method for EEG signal classification in which the classification of one subject’s EEG signals is based on features learnt from another subject. This method applies to the power spectrum density data and assigns class-dependent information weights to individual features. The informative features appear to be rather similar among different subjects, thus supporting the view that there are subject independent general brain patterns for the same mental task. Classification is done via clustering using the intelligent k-means algorithm with the most informative features from a different subject. We experimentally compare our method with others.</jats:p

Distance and consensus for preference relations corresponding to ordered partitions

Ranking is an important part of several areas of contemporary research, including social sciences, decision theory, data analysis and information retrieval. The goal of this paper is to align developments in quantitative social sciences and decision theory with the current thought in Computer Science, including a few novel results. Specifically, we consider binary preference relations, the so-called weak orders that are in one-to-one correspondence with rankings. We show that the conventional symmetric difference distance between weak orders, considered as sets of ordered pairs, coincides with the celebrated Kemeny distance between the corresponding rankings, despite the seemingly much simpler structure of the former. Based on this, we review several properties of the geometric space of weak orders involving the ternary relation “between”, and contingency tables for cross-partitions. Next, we reformulate the consensus ranking problem as a variant of finding an optimal linear ordering, given a correspondingly defined consensus matrix. The difference is in a subtracted term, the partition concentration, that depends only on the distribution of the objects in the individual parts. We apply our results to the conventional Likert scale to show that the Kemeny consensus rule is rather insensitive to the data under consideration and, therefore, should be supplemented with more sensitive consensus schemes

Removing redundant features via clustering : preliminary results in mental task separation

Recent clustering algorithms have been designed to take into account the degree of relevance of each feature, by automatically calculating their weights. However, as the tendency is to evaluate each feature at a time, these algorithms may have difficulties dealing with features containing similar information. Should this information be relevant, these algorithms would set high weights to all such features instead of removing some due to their redundant nature. In this paper we introduce an unsupervised feature selection method that targets redundant features. Our method clusters similar features together and selects a subset of representative features for each cluster. This selection is based on the maximum information compression index between each feature and its respective cluster centroid. We empirically validate out method by comparing with it with a popular unsupervised feature selection on three EEG data sets. We find that ours selects features that produce better cluster recovery, without the need for an extra user-defined parameterFinal Accepted Versio

A clustering based approach to reduce feature redundancy

This document is the Accepted Manuscript version of the following paper: Cordeiro de Amorim, R.,and Mirkin, B., ‘A clustering based approach to reduce feature redundancy’, in Proceedings, Andrzej M. J. Skulimowski and Janusz Kacprzyk, eds., Knowledge, Information and Creativity Support Systems: Recent Trends, Advances and Solutions, Selected papers from KICSS’2013 - 8th International Conference on Knowledge, Information, and Creativity Support Systems, Kraków, Poland, 7-9 November 2013. ISBN 978-3-319-19089-1, e-ISBN 978-3-319-19090-7. Available online at doi: 10.1007/978-3-319-19090-7. © Springer International Publishing Switzerland 2016.Research effort has recently focused on designing feature weighting clustering algorithms. These algorithms automatically calculate the weight of each feature, representing their degree of relevance, in a data set. However, since most of these evaluate one feature at a time they may have difficulties to cluster data sets containing features with similar information. If a group of features contain the same relevant information, these clustering algorithms set high weights to each feature in this group, instead of removing some because of their redundant nature. This paper introduces an unsupervised feature selection method that can be used in the data pre-processing step to reduce the number of redundant features in a data set. This method clusters similar features together and then selects a subset of representative features for each cluster. This selection is based on the maximum information compression index between each feature and its respective cluster centroid. We present an empirical validation for our method by comparing it with a popular unsupervised feature selection on three EEG data sets. We find that our method selects features that produce better cluster recovery, without the need for an extra user-defined parameter.Final Accepted Versio

Core clustering as a tool for tackling noise in cluster labels

Real-world data sets often contain mislabelled entities. This can be particularly problematic if the data set is being used by a supervised classification algorithm at its learning phase. In this case the accuracy of this classification algorithm, when applied to unlabelled data, is likely to suffer considerably. In this paper we introduce a clustering-based method capable of reducing the number of mislabelled entities in data sets. Our method can be summarised as follows: (i) cluster the data set; (ii) select the entities that have the most potential to be assigned to correct clusters; (iii) use the entities of the previous step to define the core clusters and map them to the labels using a confusion matrix; (iv) use the core clusters and our cluster membership criterion to correct the labels of the remaining entities. We perform numerous experiments to validate our method empirically using k-nearest neighbour classifiers as a benchmark. We experiment with both synthetic and real-world data sets with different proportions of mislabelled entities. Our experiments demonstrate that the proposed method produces promising results. Thus, it could be used as a pre-processing data correction step of a supervised machine learning algorithm

Using Taxonomy Tree to Generalize a Fuzzy Thematic Cluster

D.F. and B.M. acknowledge continuing support by the Academic Fund Program at the National Research University Higher School of Economics (grant 19-04-019 in 2018-2019) and by the International Decision Choice and Analysis Laboratory (DECAN) NRU HSE, in the framework of a subsidy granted to the HSE by the Government of the Russian Federation for the implementation of the the Russian Academic Excellence Project “5-100”. S.N. acknowledges the support by FCT/MCTES, NOVA LINCS (UID/CEC/04516/2019).This paper presents an algorithm, ParGenFS, for generalizing, or 'lifting', a fuzzy set of topics to higher ranks of a hierarchical taxonomy of a research domain. The algorithm ParGenFS finds a globally optimal generalization of the topic set to minimize a penalty function, by balancing the number of introduced 'head subjects' and related errors, the 'gaps' and 'offshoots', differently weighted. This leads to a generalization of the topic set in the taxonomy. The usefulness of the method is illustrated on a set of 17685 abstracts of research papers on Data Science published in Springer journals for the past 20 years. We extracted a taxonomy of Data Science from the international Association for Computing Machinery Computing Classification System 2012 (ACM-CCS). We find fuzzy clusters of leaf topics over the text collection, lift them in the taxonomy, and interpret found head subjects to comment on the tendencies of current research.authorsversionpublishe

Ancestral paralogs and pseudoparalogs and their role in the emergence of the eukaryotic cell

Gene duplication is a crucial mechanism of evolutionary innovation. A substantial fraction of eukaryotic genomes consists of paralogous gene families. We assess the extent of ancestral paralogy, which dates back to the last common ancestor of all eukaryotes, and examine the origins of the ancestral paralogs and their potential roles in the emergence of the eukaryotic cell complexity. A parsimonious reconstruction of ancestral gene repertoires shows that 4137 orthologous gene sets in the last eukaryotic common ancestor (LECA) map back to 2150 orthologous sets in the hypothetical first eukaryotic common ancestor (FECA) [paralogy quotient (PQ) of 1.92]. Analogous reconstructions show significantly lower levels of paralogy in prokaryotes, 1.19 for archaea and 1.25 for bacteria. The only functional class of eukaryotic proteins with a significant excess of paralogous clusters over the mean includes molecular chaperones and proteins with related functions. Almost all genes in this category underwent multiple duplications during early eukaryotic evolution. In structural terms, the most prominent sets of paralogs are superstructure-forming proteins with repetitive domains, such as WD-40 and TPR. In addition to the true ancestral paralogs which evolved via duplication at the onset of eukaryotic evolution, numerous pseudoparalogs were detected, i.e. homologous genes that apparently were acquired by early eukaryotes via different routes, including horizontal gene transfer (HGT) from diverse bacteria. The results of this study demonstrate a major increase in the level of gene paralogy as a hallmark of the early evolution of eukaryotes

Computational Generalization in Taxonomies Applied to: (1) Analyze Tendencies of Research and (2) Extend User Audiences

D.F. and B.M. acknowledge continuing support by the Academic Fund Program at the NRU HSE (grant-19-04-019 in 2018?2019) and by the DECAN Lab NRU HSE, in the framework of a subsidy granted to the HSE by the Government of the Russian Federation for the implementation of the Russian Academic Excellence Project ?5-100?. S.N. acknowledges the support by FCT/MCTES, NOVA LINCS (UID/CEC/04516/2019).We define a most specific generalization of a fuzzy set of topics assigned to leaves of the rooted tree of a domain taxonomy. This generalization lifts the set to its “head subject” node in the higher ranks of the taxonomy tree. The head subject is supposed to “tightly” cover the query set, possibly bringing in some errors referred to as “gaps” and “offshoots”. Our method, ParGenFS, globally minimizes a penalty function combining the numbers of head subjects and gaps and offshoots, differently weighted. Two applications are considered: (1) analysis of tendencies of research in Data Science; (2) audience extending for programmatic targeted advertising online. The former involves a taxonomy of Data Science derived from the celebrated ACM Computing Classification System 2012. Based on a collection of research papers published by Springer 1998–2017, and applying in-house methods for text analysis and fuzzy clustering, we derive fuzzy clusters of leaf topics in learning, retrieval and clustering. The head subjects of these clusters inform us of some general tendencies of the research. The latter involves publicly available IAB Tech Lab Content Taxonomy. Each of about 25 mln users is assigned with a fuzzy profile within this taxonomy, which is generalized offline using ParGenFS. Our experiments show that these head subjects effectively extend the size of targeted audiences at least twice without loosing quality.authorsversionpublishe