Comunicacions a congressos (Matemàtica)
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- ItemOpen AccessGeneración mejorada de ruido para oráculos de descifrado de la cifra Kyber(Universidad de La Laguna, 2026) Sebé Feixas, FrancescLa cifra Kyber es un estandar NIST de cifrado de clave publica cuya seguridad depende de la supuesta intratabilidad del problema M-LWE (module learning with errors). En este artículo estudiamos el uso de Kyber en un entorno donde el poseedor de la clave privada actua como un oráculo que colabora en el descifrado de textos cifrados que le proporcionan otras partes con el requisito de que el oraculo no debe obtener información sobre los textos en claro resultantes. Veremos que, en un escenario como el descrito, existe un riesgo de que se revele informacin que permite la reconstrucción de la clave privada. Esto obliga a limitar el numero de veces que el oráculo puede utilizar una determinada clave. El artículo propone una solución para incrementar el numero máximo de usos de cada clave.
- ItemOpen AccessQuin és l’òrgan més gran del cos?(Federació d’Entitats per a l’Ensenyament de les Matemàtiques a Catalunya, 2025) Borràs, Adelaida; Català, Tània; Barbero Sola, IvánValorant les connexions inter i extramatemàtiques, es presenta una experiència que relaciona les Matemàtiques amb el Coneixement del Medi. Durant el 2n trimestre, l’estudi sobre el nostre cos humà va virar cap als nombres, motivat per l’interès manifestat per l’alumnat i les preguntes provocades per la mestra. Així es va treballar: la quantitat de sang, l’òrgan més gran del cos, la longitud del budell… Es va cercar informació i va portar a prioritzar el sentit de la mesura. Es potencià, també, la representació que alhora fou una bona eina d’avaluació. Aquesta activitat s’ha dut a terme de nou amb l’alumnat de 2n cicle i ens ha permès aprofundir en el sentit de la mesura (magnitud, unitat i instrument), el numèric i el socioemocional amb l’objectiu d’assolir una comprensió profunda dels sabers corresponents.
- ItemOpen AccessA Quantum-Resistant Implementation of a Digital Cash System with Valued and no-Valued e-Coins(Universidad de León, Servicio de Publicaciones, 2025) Miret, Josep M. (Josep Maria) ; Sebé Feixas, Francesc; Simón, SergiDigital cash is a form of money that is minted, stored, and spent digitally. As opposed to debit or credit cards, it enables untraceable payments in the sense that the payer can acquire products while keeping their identity secret. In a recent paper, a new digital cash paradigm including the so-called no-valued e-coins was proposed. No-valued e-coins are used to perform bogus transactions which mask consumption patterns. In this paper, we analyze the aforementioned cash paradigm and investigate the possibility of implementing it over quantumresistant cryptographic schemes. This objective has been achieved using off-the-shelf cryptosystems for data encryption and digital signature which have been deeply analyzed to check they provide the required features.
- ItemOpen AccessInteger sequences from 𝑘-iterated line digraphs(CEUR Workshop Proceedings, 2024-09) Závacká, Dominika; Dalfó, Cristina; Miguel Ángel, FiolIn this paper, we focus on integer sequences corresponding to the number of vertices in 𝑘-iterated line digraphs. We begin by introducing the core concepts related to digraphs. Then, we describe a method, proposed by Dalfó and Fiol, for calculating the order of 𝑘-iterated line digraphs. We explore various families of digraphs, such as De Bruijn, Kautz, Cyclic Kautz, and Square-free digraphs. To generate integer sequences representing the number of vertices in 𝑘-iterated line digraphs, we implement an algorithm that constructs induced subdigraphs by not allowing vertices containing forbidden subwords. The results include comparisons of the obtained integer sequences with those in the OEIS database and identification of new integer sequences. Our algorithm is implemented in the computational system GAP.
- ItemOpen AccessMETMA X. Proceedings of the 10th International Workshop on Spatio-Temporal Modelling. Lleida (Spain) 1-3 June 2022(Edicions i Publicacions de la Universitat de Lleida, 2022) Comas Rodríguez, Carles; Mateu, JorgeMETMA workshop comes to its 10th edition meaning 20 years of history since its first version held in Castellon (Spain) back in 2001. Since then, its location has been moving along through Spain, Portugal, France and Italy, and has become an international reference for space-time statistics. This edition was aimed to be held in 2020 but was postponed to 2022 due to covid pandemic, and thus it somehow will be remembered as the covid-time edition. The purpose of this conference is to promote the development and application of spatial, temporal, and mainly spatio-temporal statistical methods to different fields related to the environment. The general aim is to bring together practitioners and researchers of different areas and countries all over the world. Cross-disciplinary actions to solve environmental problems are very welcome. The scientific program (http://www.metma-x.udl.cat/) features sessions covering topics on the latest advancements in theory, methods and applications, and presentations from keynotes, invited and a number of oral contributed and posters completes the program.