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  1. Article ; Online: Fuzzy Cognitive Map-Driven Comprehensive Time-Series Classification.

    Jastrzebska, Agnieszka / Napoles, Gonzalo / Homenda, Wladyslaw / Vanhoof, Koen

    IEEE transactions on cybernetics

    2023  Volume 53, Issue 2, Page(s) 1348–1359

    Abstract: This article presents a comprehensive approach for time-series classification. The proposed model employs a fuzzy cognitive map (FCM) as a classification engine. Preprocessed input data feed the employed FCM. Map responses, after a postprocessing ... ...

    Abstract This article presents a comprehensive approach for time-series classification. The proposed model employs a fuzzy cognitive map (FCM) as a classification engine. Preprocessed input data feed the employed FCM. Map responses, after a postprocessing procedure, are used in the calculation of the final classification decision. The time-series data are staged using the moving-window technique to capture the time flow in the training procedure. We use a backward error propagation algorithm to compute the required model hyperparameters. Four model hyperparameters require tuning. Two are crucial for the model construction: 1) FCM size (number of concepts) and 2) window size (for the moving-window technique). Other two are important for training the model: 1) the number of epochs and 2) the learning rate (for training). Two distinguishing aspects of the proposed model are worth noting: 1) the separation of the classification engine from pre- and post-processing and 2) the time flow capture for data from concept space. The proposed classifier joins the key advantage of the FCM model, which is the interpretability of the model, with the superior classification performance attributed to the specially designed pre- and postprocessing stages. This article presents the experiments performed, demonstrating that the proposed model performs well against a wide range of state-of-the-art time-series classification algorithms.
    Language English
    Publishing date 2023-01-13
    Publishing country United States
    Document type Journal Article
    ISSN 2168-2275
    ISSN (online) 2168-2275
    DOI 10.1109/TCYB.2021.3133597
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Recurrence-Aware Long-Term Cognitive Network for Explainable Pattern Classification.

    Napoles, Gonzalo / Salgueiro, Yamisleydi / Grau, Isel / Espinosa, Maikel Leon

    IEEE transactions on cybernetics

    2023  Volume 53, Issue 10, Page(s) 6083–6094

    Abstract: Machine-learning solutions for pattern classification problems are nowadays widely deployed in society and industry. However, the lack of transparency and accountability of most accurate models often hinders their safe use. Thus, there is a clear need ... ...

    Abstract Machine-learning solutions for pattern classification problems are nowadays widely deployed in society and industry. However, the lack of transparency and accountability of most accurate models often hinders their safe use. Thus, there is a clear need for developing explainable artificial intelligence mechanisms. There exist model-agnostic methods that summarize feature contributions, but their interpretability is limited to predictions made by black-box models. An open challenge is to develop models that have intrinsic interpretability and produce their own explanations, even for classes of models that are traditionally considered black boxes like (recurrent) neural networks. In this article, we propose a long-term cognitive network (LTCN) for interpretable pattern classification of structured data. Our method brings its own mechanism for providing explanations by quantifying the relevance of each feature in the decision process. For supporting the interpretability without affecting the performance, the model incorporates more flexibility through a quasi-nonlinear reasoning rule that allows controlling nonlinearity. Besides, we propose a recurrence-aware decision model that evades the issues posed by the unique fixed point while introducing a deterministic learning algorithm to compute the tunable parameters. The simulations show that our interpretable model obtains competitive results when compared to state-of-the-art white and black-box models.
    Language English
    Publishing date 2023-09-15
    Publishing country United States
    Document type Journal Article
    ISSN 2168-2275
    ISSN (online) 2168-2275
    DOI 10.1109/TCYB.2022.3165104
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Fuzzy-Rough Cognitive Networks: Theoretical Analysis and Simpler Models.

    Concepcion, Leonardo / Napoles, Gonzalo / Grau, Isel / Pedrycz, Witold

    IEEE transactions on cybernetics

    2022  Volume 52, Issue 5, Page(s) 2994–3005

    Abstract: Fuzzy-rough cognitive networks (FRCNs) are recurrent neural networks (RNNs) intended for structured classification purposes in which the problem is described by an explicit set of features. The advantage of this granular neural system relies on its ... ...

    Abstract Fuzzy-rough cognitive networks (FRCNs) are recurrent neural networks (RNNs) intended for structured classification purposes in which the problem is described by an explicit set of features. The advantage of this granular neural system relies on its transparency and simplicity while being competitive to state-of-the-art classifiers. Despite their relative empirical success in terms of prediction rates, there are limited studies on FRCNs' dynamic properties and how their building blocks contribute to the algorithm's performance. In this article, we theoretically study these issues and conclude that boundary and negative neurons always converge to a unique fixed-point attractor. Moreover, we demonstrate that negative neurons have no impact on the algorithm's performance and that the ranking of positive neurons is invariant. Moved by our theoretical findings, we propose two simpler fuzzy-rough classifiers that overcome the detected issues and maintain the competitive prediction rates of this classifier. Toward the end, we present a case study concerned with image classification, in which a convolutional neural network is coupled with one of the simpler models derived from the theoretical analysis of the FRCN model. The numerical simulations suggest that once the features have been extracted, our granular neural system performs as well as other RNNs.
    MeSH term(s) Cognition ; Fuzzy Logic ; Models, Theoretical ; Neural Networks, Computer ; Neurons
    Language English
    Publishing date 2022-05-19
    Publishing country United States
    Document type Journal Article
    ISSN 2168-2275
    ISSN (online) 2168-2275
    DOI 10.1109/TCYB.2020.3022527
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Book ; Online: A fuzzy-rough uncertainty measure to discover bias encoded explicitly or implicitly in features of structured pattern classification datasets

    Nápoles, Gonzalo / Koumeri, Lisa Koutsoviti

    2021  

    Abstract: The need to measure bias encoded in tabular data that are used to solve pattern recognition problems is widely recognized by academia, legislators and enterprises alike. In previous work, we proposed a bias quantification measure, called fuzzy-rough ... ...

    Abstract The need to measure bias encoded in tabular data that are used to solve pattern recognition problems is widely recognized by academia, legislators and enterprises alike. In previous work, we proposed a bias quantification measure, called fuzzy-rough uncer-tainty, which relies on the fuzzy-rough set theory. The intuition dictates that protected features should not change the fuzzy-rough boundary regions of a decision class significantly. The extent to which this happens is a proxy for bias expressed as uncertainty in adecision-making context. Our measure's main advantage is that it does not depend on any machine learning prediction model but adistance function. In this paper, we extend our study by exploring the existence of bias encoded implicitly in non-protected featuresas defined by the correlation between protected and unprotected attributes. This analysis leads to four scenarios that domain experts should evaluate before deciding how to tackle bias. In addition, we conduct a sensitivity analysis to determine the fuzzy operatorsand distance function that best capture change in the boundary regions.
    Keywords Computer Science - Machine Learning
    Subject code 006
    Publishing date 2021-08-20
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Construction and Supervised Learning of Long-Term Grey Cognitive Networks.

    Napoles, Gonzalo / Salmeron, Jose L / Vanhoof, Koen

    IEEE transactions on cybernetics

    2021  Volume 51, Issue 2, Page(s) 686–695

    Abstract: Modeling a real-world system by means of a neural model involves numerous challenges that range from formulating transparent knowledge representations to obtaining reliable simulation errors. However, that knowledge is often difficult to formalize in a ... ...

    Abstract Modeling a real-world system by means of a neural model involves numerous challenges that range from formulating transparent knowledge representations to obtaining reliable simulation errors. However, that knowledge is often difficult to formalize in a precise way using crisp numbers. In this paper, we present the long-term grey cognitive networks which expands the recently proposed long-term cognitive networks (LTCNs) with grey numbers. One advantage of our neural system is that it allows embedding knowledge into the network using weights and constricted neurons. In addition, we propose two procedures to construct the network in situations where only historical data are available, and a regularization method that is coupled with a nonsynaptic backpropagation algorithm. The results have shown that our proposal outperforms the LTCN model and other state-of-the-art methods in terms of accuracy.
    MeSH term(s) Algorithms ; Cognition/physiology ; Humans ; Models, Neurological ; Neural Networks, Computer ; Supervised Machine Learning
    Language English
    Publishing date 2021-01-15
    Publishing country United States
    Document type Journal Article
    ISSN 2168-2275
    ISSN (online) 2168-2275
    DOI 10.1109/TCYB.2019.2913960
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Long-term Cognitive Network-based architecture for multi-label classification.

    Nápoles, Gonzalo / Bello, Marilyn / Salgueiro, Yamisleydi

    Neural networks : the official journal of the International Neural Network Society

    2021  Volume 140, Page(s) 39–48

    Abstract: This paper presents a neural system to deal with multi-label classification problems that might involve sparse features. The architecture of this model involves three sequential blocks with well-defined functions. The first block consists of a ... ...

    Abstract This paper presents a neural system to deal with multi-label classification problems that might involve sparse features. The architecture of this model involves three sequential blocks with well-defined functions. The first block consists of a multilayered feed-forward structure that extracts hidden features, thus reducing the problem dimensionality. This block is useful when dealing with sparse problems. The second block consists of a Long-term Cognitive Network-based model that operates on features extracted by the first block. The activation rule of this recurrent neural network is modified to prevent the vanishing of the input signal during the recurrent inference process. The modified activation rule combines the neurons' state in the previous abstract layer (iteration) with the initial state. Moreover, we add a bias component to shift the transfer functions as needed to obtain good approximations. Finally, the third block consists of an output layer that adapts the second block's outputs to the label space. We propose a backpropagation learning algorithm that uses a squared hinge loss function to maximize the margins between labels to train this network. The results show that our model outperforms the state-of-the-art algorithms in most datasets.
    MeSH term(s) Classification/methods ; Datasets as Topic ; Neural Networks, Computer
    Language English
    Publishing date 2021-03-06
    Publishing country United States
    Document type Journal Article
    ZDB-ID 740542-x
    ISSN 1879-2782 ; 0893-6080
    ISSN (online) 1879-2782
    ISSN 0893-6080
    DOI 10.1016/j.neunet.2021.03.001
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Measuring wind turbine health using fuzzy-concept-based drifting models

    Jastrzebska, Agnieszka / Morales Hernández, Alejandro / Nápoles, Gonzalo / Salgueiro, Yamisleydi / Vanhoof, Koen

    Renewable energy. 2022 May, v. 190

    2022  

    Abstract: Time series processing is an essential aspect of wind turbine health monitoring. In this paper, we propose two new approaches for analyzing wind turbine health. Both methods are based on abstract concepts, implemented using fuzzy sets, which allow ... ...

    Abstract Time series processing is an essential aspect of wind turbine health monitoring. In this paper, we propose two new approaches for analyzing wind turbine health. Both methods are based on abstract concepts, implemented using fuzzy sets, which allow aggregating and summarizing the underlying raw data in terms of relative low, moderate, and high power production. By observing a change in concepts, we infer the difference in a turbine's health. The first method evaluates the decrease or increase in relatively high and low power production. This task is performed using a regression model. The second method evaluates the overall drift of extracted concepts. A significant drift indicates that the power production process undergoes fluctuations in time. Concepts are labeled using linguistic labels, which makes our model easier to interpret. We applied the proposed approach to publicly available data describing four wind turbines, while exploring different external conditions (wind speed and temperature). The simulation results have shown that turbines with IDs T07 and T06 degraded the most. Moreover, the deterioration was clearer when we analyzed data concerning relatively low atmospheric temperature and relatively high wind speed.
    Keywords air temperature ; power generation ; regression analysis ; time series analysis ; wind speed ; wind turbines
    Language English
    Dates of publication 2022-05
    Size p. 730-740.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2001449-1
    ISSN 1879-0682 ; 0960-1481
    ISSN (online) 1879-0682
    ISSN 0960-1481
    DOI 10.1016/j.renene.2022.03.116
    Database NAL-Catalogue (AGRICOLA)

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  8. Article ; Online: FCMpy: a python module for constructing and analyzing fuzzy cognitive maps.

    Mkhitaryan, Samvel / Giabbanelli, Philippe / Wozniak, Maciej K / Nápoles, Gonzalo / De Vries, Nanne / Crutzen, Rik

    PeerJ. Computer science

    2022  Volume 8, Page(s) e1078

    Abstract: FCMpy is an open-source Python module for building and analyzing Fuzzy Cognitive Maps (FCMs). The module provides tools for end-to-end projects involving FCMs. It is able to derive fuzzy causal weights from qualitative data or simulating the system ... ...

    Abstract FCMpy is an open-source Python module for building and analyzing Fuzzy Cognitive Maps (FCMs). The module provides tools for end-to-end projects involving FCMs. It is able to derive fuzzy causal weights from qualitative data or simulating the system behavior. Additionally, it includes machine learning algorithms (
    Language English
    Publishing date 2022-09-23
    Publishing country United States
    Document type Journal Article
    ISSN 2376-5992
    ISSN (online) 2376-5992
    DOI 10.7717/peerj-cs.1078
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Book ; Online: Long Short-term Cognitive Networks

    Nápoles, Gonzalo / Grau, Isel / Jastrzebska, Agnieszka / Salgueiro, Yamisleydi

    2021  

    Abstract: In this paper, we present a recurrent neural system named Long Short-term Cognitive Networks (LSTCNs) as a generalization of the Short-term Cognitive Network (STCN) model. Such a generalization is motivated by the difficulty of forecasting very long time ...

    Abstract In this paper, we present a recurrent neural system named Long Short-term Cognitive Networks (LSTCNs) as a generalization of the Short-term Cognitive Network (STCN) model. Such a generalization is motivated by the difficulty of forecasting very long time series efficiently. The LSTCN model can be defined as a collection of STCN blocks, each processing a specific time patch of the (multivariate) time series being modeled. In this neural ensemble, each block passes information to the subsequent one in the form of weight matrices representing the prior knowledge. As a second contribution, we propose a deterministic learning algorithm to compute the learnable weights while preserving the prior knowledge resulting from previous learning processes. As a third contribution, we introduce a feature influence score as a proxy to explain the forecasting process in multivariate time series. The simulations using three case studies show that our neural system reports small forecasting errors while being significantly faster than state-of-the-art recurrent models.
    Keywords Computer Science - Machine Learning ; Computer Science - Artificial Intelligence
    Subject code 006
    Publishing date 2021-06-30
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Book ; Online: Measuring Implicit Bias Using SHAP Feature Importance and Fuzzy Cognitive Maps

    Grau, Isel / Nápoles, Gonzalo / Hoitsma, Fabian / Koumeri, Lisa Koutsoviti / Vanhoof, Koen

    2023  

    Abstract: In this paper, we integrate the concepts of feature importance with implicit bias in the context of pattern classification. This is done by means of a three-step methodology that involves (i) building a classifier and tuning its hyperparameters, (ii) ... ...

    Abstract In this paper, we integrate the concepts of feature importance with implicit bias in the context of pattern classification. This is done by means of a three-step methodology that involves (i) building a classifier and tuning its hyperparameters, (ii) building a Fuzzy Cognitive Map model able to quantify implicit bias, and (iii) using the SHAP feature importance to active the neural concepts when performing simulations. The results using a real case study concerning fairness research support our two-fold hypothesis. On the one hand, it is illustrated the risks of using a feature importance method as an absolute tool to measure implicit bias. On the other hand, it is concluded that the amount of bias towards protected features might differ depending on whether the features are numerically or categorically encoded.

    Comment: Accepted at the Intelligent Systems Conference (IntelliSys) 2023 and will be presented on 7-8 September 2023
    Keywords Computer Science - Machine Learning ; Computer Science - Computers and Society
    Subject code 501
    Publishing date 2023-05-16
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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