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19 March 2025
  • [SSRM] Using R Shiny for teaching statistical methods | Alexandra Daub, Lars Knieper & Sophie Potts, Georg-August-University, Goettingen, Germany

    19 March 2025 - 14:00 - 15:00

    Statistics and Risk Management Seminar

    Department of Mathematics, NOVA MATH/FCT NOVA


    Title: Using R Shiny for teaching statistical methods

    Speaker: Alexandra Daub, Lars Knieper & Sophie Potts, Georg-August-University, Goettingen, Germany

    Date | Time: March 19, 2025 | 14h00

     Zoom: https://videoconf-colibri.zoom.us/j/88333359956

    AbstractIt is challenging to introduce statistical concepts to a heterogeneous student population with diverse backgrounds. Visualizations are often used in lectures and associated exercises. As these are usually done on lecture slides or (digital) notes, they remain static. In addition, the immediate programming of statistical concepts is a hindrance for students, as usually a basic understanding of the methodology is needed in advance.
    In order to provide interactive visualizations combined with explanations and further give the opportunity to adjust parameters of statistical methods, webapps for teaching purposes are developed. Therefore, the R-Shiny framework is employed. It enables users to program interactive web apps directly with R while still being flexible enough to incorporate HTML, Javascript and CSS. It offers the potential to teach statistical concepts visually and interactively. Further, students are able to get a low-barrier intuition of statistical concepts before programming and applying these themselves.

    Short Bio: Alexandra Daub, Lars Knieper and Sophie Potts are PhD students at the Chair of Spatial Data Science and Statistical Learning led by Prof. Dr. Elisabeth Bergherr at the University of Goettingen (Germany). Alexandra Daub and Lars Knieper both work on gradient-based boosting methods for estimating statistical models, with Lars Knieper focusing on the estimation of random and spatial effects and Alexandra Daub on generalized additive models for location, scale and shape. Sophie Potts is working on statistical modelling (currently a joint model for longitudinal and time-to-event data) with a special focus on their application in social sciences. During the first years of their PhDs, all three worked on a project on digital teaching material, which founded the chair's collection of Shiny applications. Both, their in-class teaching activities as well as the work on digital teaching material encompasses various areas of statistics including undergraduate statistics, statistical inference, spatial statistics and multivariate statistics.

    Organizers: Mina Norouzirad & Isabel Natário

    LogosTodos.JPG

    This work is funded by national funds through the FCT – Fundação para a Ciência e a Tecnologia, I.P., under the scope of the projects UIDB/00297/2020 (https://doi.org/10.54499/UIDB/00297/2020) and UIDP/00297/2020 (https://doi.org/10.54499/UIDP/00297/2020) (Center for Mathematics and Applications)

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23 March 2025
  • 93rd Séminaire Lotharingien de Combinatoire

    23 March 2025 - 26 March 2025 - 

      More information is available here.

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24 March 2025
  • 93rd Séminaire Lotharingien de Combinatoire

    23 March 2025 - 26 March 2025 - 

      More information is available here.

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25 March 2025
  • 93rd Séminaire Lotharingien de Combinatoire

    23 March 2025 - 26 March 2025 - 

      More information is available here.

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26 March 2025
  • 93rd Séminaire Lotharingien de Combinatoire

    23 March 2025 - 26 March 2025 - 

      More information is available here.

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  • [SDataScience] A Theoretical and Robustness Analysis of Recommender Systems | Giulia Di Teodoro (University of Pisa) & Federico Siciliano (Sapienza University of Rome)

    26 March 2025 - 14:00 - 15:00
    Auditório da Biblioteca, NOVA FCT

    Recommender Systems (RSs) are pivotal in diverse domains such as e-commerce, music streaming, and social media.

    The first part of the seminar presents a comparative analysis of key loss functions in recommender systems: Binary Cross-Entropy (BCE), Categorical Cross-Entropy (CCE), and Bayesian Personalized Ranking (BPR), which distinguish between positive items (interacted by users) and negative items. While previous studies have empirically shown that CCE outperforms BCE and BPR with the full set of negative items, we provide a theoretical explanation by proving that CCE offers the tightest lower bound on ranking metrics like Normalized Discounted Cumulative Gain (NDCG). Given that using the full set of negatives is computationally expensive, we derive bounds for these losses in negative sampling settings, establishing a probabilistic lower bound for NDCG. Our analysis shows that BPR's bound on NDCG is weaker than BCE’s, challenging the common belief that BPR is superior to BCE in recommender system training.

    Beyond loss function analysis, we turn our attention to the robustness of Sequential Recommender Systems against data perturbations. Traditional similarity measures, such as Rank-Biased Overlap, prove inadequate for evaluating ranking stability in finite-length sequences. To address this, we introduce Finite Rank-Biased Overlap, a novel similarity measure tailored for practical scenarios. Through empirical analysis of item removal at different positions in temporally ordered sequences, we demonstrate that the impact on recommendation quality is highly position-dependent, with removals at the end of sequences leading to significant performance degradation.

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  • [CourseDataScience] Neural Recommender Systems: Theory, Methods, and Applications | Giulia Di Teodoro (University of Pisa) & Federico Siciliano (Sapienza University of Rome)

    26 March 2025 - 15:00 - 17:00
    Sala Multiusos, Edifício da Biblioteca NOVA FCT

    This course provides a comprehensive overview of neural recommender systems, focusing on their foundations, state-of-the-art advancements, and practical challenges. It covers essential deep learning architectures and techniques that power modern recommender systems, exploring their role in personalizing user experiences across various domains such as e-commerce, entertainment, and social media. Key topics include sequence-based models, which capture sequential user behavior, and Transformer-based approaches, which leverage attention mechanisms for better context understanding. The course also delves into graph-based recommendation models, which model relationships between users and items in complex networks. By the end of the course, students will gain a strong understanding of neural recommender systems, their applications, and the challenges of deploying them in real-world settings.

    The course is designed for graduate students and researchers with a foundational understanding of machine learning and deep learning. Familiarity with basic neural network architectures (e.g., CNNs, RNNs) is recommended.

    The course will appeal to students from related areas such as natural language processing, and computer vision, and optimization, given its focus on domain-specific applications. The emphasis on ethical considerations and explainability will also interest students working on Safe, Explainable, and Trustworthy AI.

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27 March 2025
  • [CourseDataScience] Neural Recommender Systems: Theory, Methods, and Applications | Giulia Di Teodoro (University of Pisa) & Federico Siciliano (Sapienza University of Rome)

    27 March 2025 - 10:00 - 12:00
    Sala Multiusos, Edifício da Biblioteca NOVA FCT

    This course provides a comprehensive overview of neural recommender systems, focusing on their foundations, state-of-the-art advancements, and practical challenges. It covers essential deep learning architectures and techniques that power modern recommender systems, exploring their role in personalizing user experiences across various domains such as e-commerce, entertainment, and social media. Key topics include sequence-based models, which capture sequential user behavior, and Transformer-based approaches, which leverage attention mechanisms for better context understanding. The course also delves into graph-based recommendation models, which model relationships between users and items in complex networks. By the end of the course, students will gain a strong understanding of neural recommender systems, their applications, and the challenges of deploying them in real-world settings.

    The course is designed for graduate students and researchers with a foundational understanding of machine learning and deep learning. Familiarity with basic neural network architectures (e.g., CNNs, RNNs) is recommended.

    Yes, the course will appeal to students from related areas such as natural language processing, and computer vision, and optimization, given its focus on domain-specific applications. The emphasis on ethical considerations and explainability will also interest students working on Safe, Explainable, and Trustworthy AI.

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  • [CourseDataScience] Neural Recommender Systems: Theory, Methods, and Applications | Giulia Di Teodoro (University of Pisa) & Federico Siciliano (Sapienza University of Rome)

    27 March 2025 - 14:00 - 16:00
    Sala Multiusos, Edifício da Biblioteca NOVA FCT

    This course provides a comprehensive overview of neural recommender systems, focusing on their foundations, state-of-the-art advancements, and practical challenges. It covers essential deep learning architectures and techniques that power modern recommender systems, exploring their role in personalizing user experiences across various domains such as e-commerce, entertainment, and social media. Key topics include sequence-based models, which capture sequential user behavior, and Transformer-based approaches, which leverage attention mechanisms for better context understanding. The course also delves into graph-based recommendation models, which model relationships between users and items in complex networks. By the end of the course, students will gain a strong understanding of neural recommender systems, their applications, and the challenges of deploying them in real-world settings.

    The course is designed for graduate students and researchers with a foundational understanding of machine learning and deep learning. Familiarity with basic neural network architectures (e.g., CNNs, RNNs) is recommended.

    Yes, the course will appeal to students from related areas such as natural language processing, and computer vision, and optimization, given its focus on domain-specific applications. The emphasis on ethical considerations and explainability will also interest students working on Safe, Explainable, and Trustworthy AI.

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11 April 2025
  • Lisbon Young Mathematicians Conference – LYMC 2025

    11 April 2025 - 12 April 2025 - 

    More information is available here.

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12 April 2025
  • Lisbon Young Mathematicians Conference – LYMC 2025

    11 April 2025 - 12 April 2025 - 

    More information is available here.

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