Rojas, Omar
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Preferred name
Rojas, Omar
Official Name
Rojas Altamirano, Omar Guillermo
Alternative Name
orojas
Main Affiliation
ORCID
Scopus Author ID
22954196800
Researcher ID
K-1066-2013

Research Output
Now showing 1 - 10 of 64
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Publication

Adaptive efficiency of the Mexican Stock Exchange

2018 , Esmeralda Brito-Cervantes , Semei Coronado , Manuel Morales-García , Rojas, Omar

Purpose The purpose of this paper is to analyse the adaptive market efficiency in the price–volume (P–V) relationship of the stocks listed in the Mexican Stock Exchange. The period under study goes from 1982 to 2015. In order to detect causality and, thus, determine adaptive efficiency in the market, one linear and two non-linear tests are applied. There are few papers in the literature that study the P–V relationship in Latin American markets; as such, this paper may be of interest and importance to financial academics and practitioners alike. Design/methodology/approach The Diks and Panchenko (DP) non-parametric Granger causality and the Brooks and Hinich (BH) cross-bicorrelation tests are applied. Findings Derived from the DP test, the findings show that there exists bi-directional non-linear Granger causality in 25.71 per cent of the firms studied, compared to 8 per cent when applying the linear Granger causality test. Therefore, there is evidence of weak-form efficiency in the market. From the BH test, evidence is shown of the adaptive market efficiency, since 71.42 per cent of firms exhibited some form of non-linear dependence in certain periods of time. With these results, the information process should be better studied for a greater comprehension of regulatory policies in the market and better decision-making tools for the investors. Originality/value This paper complements studies on the P–V relationship and efficiency in a Latin American market.

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On the Fitness Functions Involved in Genetic Algorithms and the Cryptanalysis of Block Ciphers

2023 , Osmani Tito-Corrioso , Mijail Borges-Quintana , Miguel A. Borges-Trenard , Rojas, Omar , Guillermo Sosa-Gómez

There are many algorithms used with different purposes in the area of cryptography. Amongst these, Genetic Algorithms have been used, particularly in the cryptanalysis of block ciphers. Interest in the use of and research on such algorithms has increased lately, with a special focus on the analysis and improvement of the properties and characteristics of these algorithms. In this way, the present work focuses on studying the fitness functions involved in Genetic Algorithms. First, a methodology was proposed to verify that the closeness to 1 of some fitness functions’ values that use decimal distance implies decimal closeness to the key. On the other hand, the foundation of a theory is developed in order to characterize such fitness functions and determine, a priori, if one method is more effective than another in the attack to block ciphers using Genetic Algorithms.

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FACTORS ASSOCIATED WITH ELECTRICITY LOSSES: A PANEL DATA PERSPECTIVE

2020 , Briseño, Hugo , Rojas, Omar

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Transfer Entropy Granger Causality between News Indices and Stock Markets in U.S. and Latin America during the COVID-19 Pandemic

2022 , Semei Coronado , Jose N. Martinez , Victor Gualajara , Rojas, Omar

The relationship between three different groups of COVID-19 news series and stock market volatility for several Latin American countries and the U.S. are analyzed. To confirm the relationship between these series, a maximal overlap discrete wavelet transform (MODWT) was applied to determine the specific periods wherein each pair of series is significantly correlated. To determine if the news series cause Latin American stock markets’ volatility, a one-sided Granger causality test based on transfer entropy (GC-TE) was applied. The results confirm that the U.S. and Latin American stock markets react differently to COVID-19 news. Some of the most statistically significant results were obtained from the reporting case index (RCI), A-COVID index, and uncertainty index, in that order, which are statistically significant for the majority of Latin American stock markets. Altogether, the results suggest these COVID-19 news indices could be used to forecast stock market volatility in the U.S. and Latin America.

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A systemic approach to self-management in SMEs. Case: Mexican lodging organisations

2020 , Núñez-Ríos, Juan E. , Soto-Pérez, Manuel , J. Yvette Sánchez García , Rojas, Omar

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Self-efficacy and job satisfaction as antecedents of citizenship behaviour in private schools

2019 , Soto-Pérez, Manuel , Rojas, Omar

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Causality patterns for Brent, WTI, and Argus oil prices

2016 , Semei Coronado , Thomas M. Fullerton , Rojas, Omar

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Factors to Foster Organizational Sustainability in Tourism SMEs

2020 , Núñez-Ríos, Juan E. , Sánchez-García, Jacqueline Y. , Rojas, Omar , Olivares-Benitez, Elias

Small and medium-sized tourism companies (SMEs) strongly depend on their collaborators to achieve competitiveness and sustainability. In this sense, these organizations need to identify those factors that help them to use their resources and efforts to achieve the aforementioned goals. This article proposes a model oriented to organizational sustainability in the tourism sector. A systemic approach was adopted to articulate this research; therefore, the soft systems methodology was applied to structure the problem and express a conceptual model that suggests relationships as an alternative solution to the expressed problem. Partial least squares path modeling was applied to statistically validate the relationships expressed in the construct. Results suggest that the relationships proposed in the construct are valid and may promote organizational sustainability. The ideas developed are restricted to the organizational domain and although the results apply in a Mexican context, this potential limitation can be offset by the multi-methodological approach proposed, extending the model’s application to other types of organizations. This study may enable scholars and managers to improve communication and inter-organizational relationships, allowing organizations to focus their strategies and efforts using systems thinking to increase responsiveness and adaptation.

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Analysis of the Number of Sides of Voronoi Polygons in PassPoint

2021 , Lisset Suárez-Plasencia , Joaquín A. Herrera-Macías , Carlos M. Legón-Pérez , Raisa Socorro-LLanes , Rojas, Omar , Sosa-Gómez, Guillermo

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Using hadamard transform for cryptanalysis of pseudo-random generators in stream ciphers

2020 , Sosa-Gómez, Guillermo , Rojas, Omar , Páez-Osuna, O.

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