News

30 August: Dhandabani S (QSMS seminar)

The QSMS Research Group (BME) will be hosting two seminars this August 2022. One-to-one meetings with the speakers can be arranged; please contact the seminar organizers, Dr. Noémie Cabau (cabau.noemie@gtk.bme.hu) and Dr. Arseniy Samsonov (samsonov.arseniy@gtk.bme.hu).  

Dhandabani S from the Indian Institute of Technology Madras (Decision Engineering Lab, Department of Management Studies) will be presenting his paper Modeling interactions between vertically cooperative and horizontally competitive newsvendor on the 30th of August 2022 at 4PM, Room QA406. 

Abstract:  Consider a market served by both the supplier and the retailer, a typical example of a dual-channel supply chain. Supplier holds a fixed number of perishable inventories and shares them with the retailer for better reach. Also, because of the price matching guarantee, both the parties agree on a uniform retail price for customers, and it is set by the supplier along with the wholesale price. We assume that both the parties are profit-maximising newsvendors, i.e., retailer and supplier are quantity-setting and price-setting newsvendors, respectively. However, given the nature of the setting, their decisions are dependent on each other. As a result, none of them can control the environment solely and both set out to maximise their own profits, which calls for a game-theoretic perspective on the coopetitive (vertically cooperative and horizontally competitive) two-newsvendor setting. We model the interactions between the supplier and retailer as a Stackelberg game, with the supplier being the leader and the retailer being the follower. Given the price[1]sensitive nature of the demand, the retailer estimates her optimal quantity as a function of retail and wholesale prices as a function of the reaction curve. Exploiting the backward induction, the supplier leverages the retailer’s optimal quantity to base its pricing decisions. As the optimal solution becomes intractable for a generic demand uncertainty, focusing only on additive demand uncertainty, we derive sufficient optimality conditions for the supplier’s profit function to be concave with respect to both the retail and wholesale prices. Furthermore, we compute the best feasible set of quantity and price points that satisfy the already established restrictions and assumptions. Finally, extensive sensitivity analysis of the model parameters yields the following several managerial insights, out of which a few novel and counterintuitive are as follows: (i) supplier’s expected profit decreases with the capacity, (ii) the more the variation, supplier’s gain increases whereas retailer’s gain decreases, (iii) with a highly sensitive market, both the parties’ profits decrease, and (iv) retailer’s profit is concave with respect to the market potential. 

23 August: Mikhail Freer (QSMS seminar)

The QSMS Research Group (BME) will be hosting two seminars this August 2022. One-to-one meetings with the speakers can be arranged; please contact the seminar organizers, Dr. Noémie Cabau (cabau.noemie@gtk.bme.hu) and Dr. Arseniy Samsonov (samsonov.arseniy@gtk.bme.hu).  

Mikhail Freer from the University of Essex (Department of Economics) will be presenting his paper Constitutional Design (co-authored with César Martinelli) on the 23rd of August 2022 at 4PM, Room QA406.  

Abstract: Constitution is the cornerstone of any democracy: defining both the basic rights of citizens and the rules of the political process. However, most political economy literature frequently overlooks the constitution as a whole, focusing on bargaining between legislator and executive. This paper expands the scope and considers all three branches of power in the constitutional mechanism. First, we show that the constitutional mechanism (even with the accountability of the executive and legislator) cannot be credible without the presence of the “fourth power” (civic society). However, this fourth power is not directly governed by the constitution, and to restore the credibility of the constitution, the two key features are (1) society is affected by the outcomes of legislative bargaining, and (2) the judiciary is responsive to public opinion. However, these features are not enough to restore the “efficiency” of the constitution; to do so, we need to ensure that society does not stop pressuring the government with just the resignation of the corresponding official but gets a more direct involvement in the further legislative bargaining. 

Koltai’s paper published in The Int. J. Manag. Educ.

The paper titled “Performance evaluation of teams in business simulation games with weight restricted data envelopment analysis models.” (joint with Tamás, A.) has been published in The International Journal of Management Education.

Business simulation games are widely used in higher education, management training, and executive management development programmes. The evaluation of the performance of participants is generally subjective and is based on the trainer’s perception of the importance of several evaluation criteria. In this paper, data envelopment analysis (DEA) is proposed for such evaluation. Input-oriented constant return-to-scale DEA models are used for evaluating the performance of teams participating in business simulation games (BSG). A car engine manufacturing game played by MBA master students is used to illustrate the proposed method. Weight restrictions are applied to obtain efficiency scores which can be used as an alternative to financial measures. The relationship between the efficiency measure and the financial measure is statistically analyzed. The main conclusion of the presented research is that if weight restriction parameters are properly set, DEA results can provide reliable and detailed information about participants’ performance, about the shortcomings of decisions made during the games, and about possible ways to improve performance.

The paper presents the first application of DEA in the area of performance evaluation in BSG, consequently it can be considered a significant extension of the DEA application domain.

Koltai, T. and Tamás, A. (2022). Performance evaluation of teams in business simulation games with weight restricted data envelopment analysis models. The International Journal of Management Education, Volume 20, Issue 3, p. 17.

https://doi.org/10.1016/j.ijme.2022.100688

Kóczy’s paper published in AnOR

Kóczy’s paper titled “Core-stability over networks with widespread externalities” has been published in the Annals of Operations Research.

The Covid-19 epidemic highlighted the significance of externalities: contacts with other people affect the chances of getting infected for our entire network. We study endogenous network formation where not only players or pairs but larger coalitions can, cooperatively change the network. We introduce a model for coalitional network stability for networks with widespread externalities. The network function form generalises the partition function form of cooperative games in allowing the network to be taken into account. The recursive core for network function form games generalises the recursive core for such environments. We present two simple examples to illustrate positive and negative externalities. The first is of a favour network and show that the core is nonempty when players must pay transfers to intermediaries; this simple setting also models economic situations such as airline networks. The second models social contacts during an epidemic and finds social bubbles as the solution.

Kóczy, L.Á. Core-stability over networks with widespread externalities. Ann Oper Res (2022). https://doi.org/10.1007/s10479-022-04669-5

23 February: Maya Jalloul (QSMS seminar)

Presenting “Narrative adoption and strategic timing of disclosure?” at 16:00-17:30 online: Click here to join the meeting

On 23 February 2022, we have Maya Jalloul of Lebanese American University visiting us. She is going to give a seminar on “Narrative adoption and strategic timing of disclosure.” at 16:00 online Click here to join the meeting. Please help the organisers by registering in advance at egervari.zsuzsanna@gtk.bme.hu Registration is free. Event can only be attended with vaccination card.

Abstract: This paper investigates a model with two strategic politicians, a proponent and an opponent, and a group of non-strategic voters. The proponent, who is the first mover, has a narrative that she aims to convey to the voters; whereas the opponent’s objective is to divert the voters away from it. The strategic decision of the proponent is when to disclose her narrative with the objective to maximise the adoption of this narrative by a deadline, and that of the opponent is when to disclose the refutation. The voters opinions updating rule follows an average-based De Groot learning concept where a voter splits his attention between the two politicians, his own opinion and his neighbours. We show that once the proponent discloses her narrative, it is optimal for the opponent to disclose her refutation, and that the proponent faces a trade-off between early and late disclosure. We determine the optimal timing of disclosure for the cases of one voter and a group of voters and we examine connections among voters over a specific set of networks, while considering two types of voters, supporters and non-supporters. We also investigate the impact of homophily on timing of disclosure and we find that with higher homophily, the narrative adoption of the supporter is higher and that of the non-supporter is lower.

22 February: Christopher P. Stapenhurst (QSMS seminar)

Presenting “Can Media Pluralism Be Harmful to News Quality?” at 16:00-17:30 QA 406

On 22 February 2022, we have Chistopher P. Stapenhurst of University of Edinburgh visiting us. He is going to give a seminar on “Lemons by design: sowing secrets that curb corruption” (with Andrew Clausen) at 16:00 in room QA406. Please help the organisers by registering in advance at egervari.zsuzsanna@gtk.bme.hu Registration is free. Event can only be attended with vaccination card.

Abstract: We study a problem in which a polluting firm can bribe an inspector to conceal evidence of illegal behaviour. We find that the best way to deter bribes involves paying secret rewards and sending secret clues. The regulator promises to pay a secret reward to either the firm or the inspector when evidence is reported; it then gives them different clues about who will be rewarded. These clues are carefully constructed to engineer the worst possible lemons problem in the market for concealment: each player only wants to conceal evidence if they believe that the other player is more optimistic about being rewarded. But they cannot both be more optimistic in equilibrium, so no concealment takes place. As well as deterring bribes cheaply, this scheme demonstrates the full extent of contagious adverse selection in a bilateral trade environment.

Kóczy’s paper published in Games

Kóczy’s paper titled “Exits from the European Union and Their Effect on Power Distribution in the Council” (joint work with Dóra Gréta Petróczy and Mark Francis Rogers) has been published in Games.

Debates on an EU-leaving referendum arose in several member states after Brexit. This paper studies the effects of an additional exit on the power distribution in the Council of the European Union. Power indices of the member states are studied both with and without the country which might leave the union. Results show a pattern connected to a change in the number of states required to meet the 55% threshold. An exit that modifies this number benefits the countries with high population, while an exit that does not cause such a change benefits the small member states. According to the calculations, only the exit of Poland would be supported by the qualified majority of the Council.

Petróczy, D.G.; Rogers, M.F.; Kóczy, L.Á. Exits from the European Union and Their Effect on Power Distribution in the Council. Games 202213, 18. https://doi.org/10.3390/g13010018

9 February: Federico Innocenti (QSMS Seminar)

(QSMS Seminar)

Presenting “Can Media Pluralism Be Harmful to News Quality?” at 16:00-17:30 online Click here to join the meeting

On 9 February 2022, we have Federico Innocenti of University of Mannheim visiting us. He is going to give a seminar on “Can Media Pluralism Be Harmful to News Quality?” at 16:00 online Click here to join the meeting. Please help the organisers by registering in advance at egervari.zsuzsanna@gtk.bme.hu Registration is free. Event can only be attended with vaccination card.

Abstract: I study a Bayesian persuasion model that connects two stylized facts characterizing the Internet: a great diversity of news sources and the proliferation of disinformation. I show that competition between news sources with opposite biases reduces information quality when news consumers have limited attention because of the endogenous formation of echo chambers. According to the standard narrative, echo chambers arise because news consumers exhibit confirmation bias. I show that even unbiased and rational news consumers devote their limited attention to like-minded news sources in equilibrium. Confirmation bias thus arises endogenously because news sources have no incentive to provide valuable information.

8 February: Giovanni Andreottola (QSMS Seminar)

Presenting “Polarization and Policy Design” at 16:00-17:30 in QA406.

On 8 February 2022, we have Giovanni Andreottola of University of Naples visiting us. He is going to give a seminar on “Polarization and Policy Design” at 16:00 in room A406 in Building Q, Budapest University of Technology and Economics, Faculty of Economic and Social Sciences, Magyar tudósok körútja 2, 1117 Budapest. Please help the organisers by registering in advance at egervari.zsuzsanna@gtk.bme.hu Registration is free. Event can only be attended with vaccination card.

Abstract: Voters in the U.S. and elsewhere have become highly polarized. How does this impact policymaking? We build a model to examine this question in the context of distributive politics and find that polarization can have a non-monotonic effect on equity. Political turnover and the inter-temporal resolution of policy uncertainty play key roles for this result. The implications of alternative electoral systems are also examined: contrary to conventional
wisdom, proportional systems may exacerbate partisan policymaking compared to majoritarian systems.