Robust newsvendor games with ambiguity in demand distributions

In classical newsvendor games, vendors collaborate to serve their aggregate demand whose joint distribution is assumed known with certainty. We investigate a new class of newsvendor games with ambiguity in the joint demand distributions, which is represented by a Fréchet class of distributions with some, possibly overlapping, marginal information. To model this new class of games, we use ideas from distributionally robust optimization to handle distributional ambiguity and study the robust newsvendor games. We provide conditions for the existence of core solutions of these games using the structural analysis of the worst-case joint demand distributions of the corresponding distributionally robust newsvendor optimization problem

OPPORTUNITIES AND CHALLENGES IN PROMOTING THE ROLE OF INTERNATIONAL INTEGRATION FOR SOCIO-ECONOMIC DEVELOPMENT IN VIETNAM

International integration is an objective trend, strongly attracting the participation of all countries and regions in the world. International integration is strongly affecting all nations, all aspects of socio-economic life. For Vietnam, international integration has brought opportunities and good chances, while it also posed real challenges and risks in promoting the role of the state in the socio-economic development. Therefore, the urgent issue at the present is to identify fully, deeply and to figure out reasonable strategies, to take advantage of opportunities, to overcome risks in order to promote the role of international integration for socio-economic development in Vietnam with important theoretical and practical meanings.  Article visualizations

Optimal monetary policy in a dollarized economy

This thesis attempts to specify an optimal monetary policy for a developing country with partial dollarization. In particular, optimal monetary policy options are investigated within the context of an estimated Dynamic Stochastic General Equilibrium (DSGE) model in order to examine the interaction of the monetary authority with the rest of the economy. The first chapter introduces the research questions, scope of the research, and a brief illustration of dollarization in developing countries in general and Vietnam in particular. Chapter 2 begins with the formulation of an open economy DSGE model with typical features of a developing country, including partial dollarization and a chronic budget deficit fiscal rule. A parameterized version of the model is then simulated to investigate the sensitivity and significance of various nominal and real frictions in the model. The remainder of the chapter is devoted to an examination of the role of partial dollarization feature in the model economy. Chapter 3 estimates the theoretical model using a dataset from Vietnam - a developing country in the Southeast Asia. This is the first estimated DSGE model for Vietnam, as far as my supervisors and I are aware. In particular, the model is estimated with Bayesian estimation method based on thirteen macroeconomic series with the presence of orthogonal structural shocks on both supply and demand side. The final section of this chapter is devoted to a discussion of the relative importance of various shocks and frictions for explaining the dynamics of the model economy and an evaluation of the model’s empirical properties using standard validation techniques. Estimation results are then integrated in the fourth chapter in order to specify an optimal monetary policy under the estimated model. The first section introduces Currie & Levine (1993)’s method to optimal policy problem which uses standard control state-space approach and Bellman’s principle of optimality. Following the derivation of the optimal monetary policy problem with linear, forward-looking constraints and a quadratic objective, asymptotic losses are then presented for a Ramsey policy, a discretionary policy, and an ex ante optimized simple Taylor-type rule. The last section of the chapter discusses the dynamics of the model economy under optimal policy. Among the major findings was the superiority of the optimal Ramsey policy over other policy options. Chapter 5 concludes with some brief comments on the results of general interest, the contributions of the research, and then proposes a potential agenda for future research

Teacher’s and learner’s roles in autonomy-oriented foreign language teaching: a theoretical investigation

The global language teaching community has largely spotlighted students’ autonomous learning for the last few decades. Through the thorough review of the existing literature on learner autonomy, this article aims to theoretically investigate this concept as well as clearly specify the roles played by teachers and students in an autonomy-oriented classroom. Autonomous learning is not at all synonymous with the absolute elimination of teacher’s role and learner-learner relationships. In fact, language instructors need to comprehend their roles in a multidimensional way, and students are supposed to be responsibly active for their own learning process as well as positively interdependent for academic cooperation

ANALYZE THE TREATMENT REGIMENS AND THROMBOSIS PROPHYLAXIS USED IN CORONARY ARTERY INTERVENTION AT INTERVENTIONAL CARDIOLOGY UNIT IN CAN THO CENTRAL GENERAL HOSPITAL

Objective: The study was conducted to analyze the rationality of treatment regimens and thrombosis prophylaxis used in coronary artery intervention to compare to guidelines for treatment according to VNHA and recommendation of ACC/AHA at Interventional cardiology in Can Tho Central General Hospital. Methods: The cross-sectional study was based on the data collected from entire medical records of patients at Interventional cardiology in Can Tho Central General Hospital from August 2017 to February 2018. The rationality of the antithrombotic regimen used at the Hospital is assessed through criteria such as medical combination, dosage, time to take medicine, clinical trials during the treatment. Results: The study found that 95.6% and 90.7% were suitable for medical combination before and after PCI; 100% fit for the use of medicine; and 100% was suitable for antithrombotic agents and clinical trials during treatment time; in terms of dosage, the result showed that entrance and maintenance were 84.9% and 100% for aspirin respectively; 71.7% and 100% for clopidogrel; 100% and 94.7% for ticagrelor; 90.2-92.8% and 98.1% for enoxaparin; especially, heparin-100% anticoagulant was appropriate to recommend. Conclusion: The study showed that treatment regimens and thrombosis prophylaxis in percutaneous coronary intervention at Interventional cardiology in Can Tho Central General Hospital were quite suitable compared to the recommendations of the Heart Association. The results from the study are a scientific basis for the Hospital to maintain or consider adjustments to improve the quality of treatment, ensure the effectiveness and safety of patients

Robust unit commitment with n - 1 security criteria

The short-term unit commitment and reserve scheduling decisions are made in the face of increasing supply-side uncertainty in power systems. This has mainly been caused by a higher penetration of renewable energy generation that is encouraged and enforced by the market and policy makers. In this paper, we propose a two-stage stochastic and distributionally robust modeling framework for the unit commitment problem with supply uncertainty. Based on the availability of the information on the distribution of the random supply, we consider two specific models: (a) a moment model where the mean values of the random supply variables are known, and (b) a mixture distribution model where the true probability distribution lies within the convex hull of a finite set of known distributions. In each case, we reformulate these models through Lagrange dualization as a semi-infinite program in the former case and a one-stage stochastic program in the latter case. We solve the reformulated models using sampling method and sample average approximation, respectively. We also establish exponential rate of convergence of the optimal value when the randomization scheme is applied to discretize the semi-infinite constraints. The proposed robust unit commitment models are applied to an illustrative case study, and numerical test results are reported in comparison with the two-stage non-robust stochastic programming model

Achieving Better Regret against Strategic Adversaries

We study online learning problems in which the learner has extra knowledge about the adversary's behaviour, i.e., in game-theoretic settings where opponents typically follow some no-external regret learning algorithms. Under this assumption, we propose two new online learning algorithms, Accurate Follow the Regularized Leader (AFTRL) and Prod-Best Response (Prod-BR), that intensively exploit this extra knowledge while maintaining the no-regret property in the worst-case scenario of having inaccurate extra information. Specifically, AFTRL achieves $O(1)$ external regret or $O(1)$ \emph{forward regret} against no-external regret adversary in comparison with $O(\sqrt{T})$ \emph{dynamic regret} of Prod-BR. To the best of our knowledge, our algorithm is the first to consider forward regret that achieves $O(1)$ regret against strategic adversaries. When playing zero-sum games with Accurate Multiplicative Weights Update (AMWU), a special case of AFTRL, we achieve \emph{last round convergence} to the Nash Equilibrium. We also provide numerical experiments to further support our theoretical results. In particular, we demonstrate that our methods achieve significantly better regret bounds and rate of last round convergence, compared to the state of the art (e.g., Multiplicative Weights Update (MWU) and its optimistic counterpart, OMWU)