News

Steven Kivinen (University of Graz) will be presenting his paper “On the Manipulability of Equitable Voting Rules “ on December 13th at 10 AM, room QA 405. One-to-one meetings with the speaker 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).  

Abstract:   

We consider the equity-manipulability trade-off when voting over two alternatives. Pairwise equity is a weakening of anonymity requiring certain permutations of the voters’ identities to preserve the outcome of the election. l-robust group strategy-proofness (l-RGSP) and fine robust group strategy-proofness (FRGSP) are notions of group strategy-proofness that allow voters to have different beliefs about players’ types (Kivinen and Tumennasan, 2021). Our main results show that, under mild conditions, for pairwise equitable voting rules anonymity is equivalent to 2-RGSP, 3-RGSP, and FRGSP. In this way, anonymity is special in its equity and non-manipulability. These results follow from several preliminary results, one of which equates 2-RGSP to comonotonicity and swap-robustness. Finally, we consider the manipulability of k-unanimous rules, and 2-RGSP when agents can be indifferent and abstain.

Mats Köster (Central European University, Vienna) will be presenting his paper “Conversations“ (co-authored with Paul Voss) on December 6th at 10 AM, room QA 405. One-to-one meetings with the speaker 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).  

Abstract:   We develop a theory of conversations. Two agents with different interests take turns choosing the topic of the conversation. Talking about a single topic allows to delve deeper, making the conversation more informative (or enjoyable). To capture this, we assume that the marginal utility from conversing increases when the agents stay on topic. The equilibrium conversation is extreme: it either maximizes or minimizes welfare. Long conversations tend to be deep and thus efficient. Short ones are often superficial. The topic of a deep conversation depends in subtle ways on who speaks when. Applications range from echo chambers to team production. 

Toygar Kerman (Corvinus University) will be presenting his paper “Persuading Communicating Voters“ (co-authored with Anastas P. Tenev)) on November 29th at 10 AM, room QA 3rd floor conference roomn. One-to-one meetings with the speaker 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).  

Abstract:  We study a multiple-receiver Bayesian persuasion model in which the sender wants to implement a proposal and commits to a signal which sends correlated messages to multiple receivers who have homogeneous beliefs. Receivers are connected in a network and can perfectly observe their direct neighbors’ messages. After updating their beliefs, receivers vote for or against the proposal. The setup with limited information spillovers creates a significant complication in designing optimal signals. We simplify the sender’s problem by providing partial characterizations for optimal communication and consider applications which are characterized by distinct patterns of voter interaction. We show that the sender can achieve the upper bound of the value (i.e. the case with no spillovers) in most of the applications. Surprisingly, more communication among the receivers can even be strictly better for the sender and hence strictly worse for the voters. 

 Robert Schmidt (University of Hagen) will be presenting his paper “On the timing of moves in two-player games“ (co-authored with Leanne Streekstra, Larry Karp, and Leo Simon) on November 22nd at 10 AM, room QA405. One-to-one meetings with the speaker 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).  

Abstract:  We analyze two-player games in continuous time in which each player is free to decide when to move and what action to implement. The number of moves per player is restricted to (at most) one. We arrive at sharp predictions about the equilibrium outcome in certain classes of games, for which we can predict the timing of players’ moves, as well as the identity of the leader in a unique equilibrium outcome with sequential moves. This includes games with a second-mover advantage and non-trivial action sets that are traditionally analyzed in static settings. We illustrate the strength of our general modeling framework by applying it to canonical games from industrial economics and political economics such as price competition, and electoral competition where candidates differ in their “valence”.

Sreoshi Banerjee (QSMS Research Group, BME)  will be presenting her paper “GENERALIZED WELFARE LOWER BOUNDS AND STRATEGYPROOFNESS IN
SEQUENCING PROBLEMS “ on October 25th at 10 AM, room QA405. One-to-one meetings with the speaker 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).  

Abstract:  In an environment with private information, we study the class of sequencing problems with welfare lower bounds. The ‘generalized welfare lower bound’ is a universal representation of some of the specific lower bounds that have been previously studied in the literature. Every agent is offered protection in the form of a minimum guarantee on their utilities. We provide a necessary and sufficient condition to identify an outcome-efficient and strategyproof mechanism that satisfies the generalized welfare lower bound. We then characterize the entire class of mechanisms that satisfy outcome efficiency, strategyproofness, and generalized welfare lower bound. These are termed as ‘relative pivotal mechanisms’. Our paper proposes relevant theoretical applications namely; ex-ante initial order, identical costs bound and expected cost bound. We also give insights on the issues of feasibility and/or budget balance. 

Ryan Tierney from the University of Southern Denmark will be presenting his paper “Crowding in School Choice“ on October 18th at 10 AM, room QA405. One-to-one meetings with the speaker 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).  

Abstract:  We consider the market design problem of matching students to schools in the presence of crowding effects. These effects are salient in parents’ decision making and the empirical literature; however, they cause major difficulties in the design of satisfactory mechanisms and, as such, are not currently considered. We propose a new framework and an equilibrium notion that accommodates crowding, no-envy, and respect for priorities. The equilibrium has a student-optimal element that induces an incentive compatible mechanism and is implementable via a novel algorithm. Moreover, analogs of fundamental structural results of the matching literature—the Rural Hospitals Theorem, welfare lattice, etc.—survive.

Vivien Surman from BME, Management department, will be presenting her paper “Characterizing clusters of students and supervisors based on an empirical study in the case of project work courses“ on October 11th at 10 AM, room QA405. One-to-one meetings with the speaker 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).  

Abstract:  The purpose of this research is to describe the different clusters of students completing project work courses and to characterize lecturers acting as supervisors as well. The existence of different student groups setting different requirements against the supervising process has been emerged by supervisor focus group interviews in the improvement process of a service quality framework for project work courses. Cluster analyses based upon data from this service quality framework have proved the presence of three well-definable student groups. At the same time, the specific attributes of the supervisors including age, experience, grade distribution have also been gathered and analysed. The student classification is based on feedbacks of 1500 students. Supervisor characterization results from the analyses of 800 previously finished project work courses. As a result, it could be confirmed that both the students and the supervisors could be classified into well-defined groups in the case of project work courses. Finally, the characteristics of the identified groups of students and that of supervisors have been compared with statistical methods, highlighting connections between the groups. As these project work courses are remarkable cornerstones of total higher education student experience, characterizing the service quality features of the supervision process is vital. On the long run, the successful pairing of student groups with supervisor groups having specific features could be carried out for the sake of successful student accomplishment and for standardizing the supervision process as well. 

Dov Samet from the Coller School of Management at Tel Aviv University will be presenting his paper “Desirability” on October 4th at 10 AM, room QA405. One-to-one meetings with the speaker 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).  

Abstract:  We propose a model of an agent’s probability and utility that is a compromise between Savage (1954) and Jeffrey (1965). In Savage’s model the probability-utility pair is associated with preferences over acts which are assignments of consequences to states. The probability is defined on the state space, and the utility function on consequences. Jeffrey’s model has no consequences, and both probability and utility are defined on the same set of propositions. The probability-utility pair is associated with a desirability relation on propositions. Like Savage we assume a set of consequences and a state space. However, we assume that states are comprehensive, that is, each state describes a consequence, as in Aumann (1987). Like Jeffrey, we assume that the agent has a preference relation, which we call desirability, over events, which by definition involves uncertainty about consequences. For a given probability and utility of consequences, the desirability relation is presented by conditional expected utility, given an event. We axiomatically characterize desirability relations that are represented by a probability-utility pair. We characterize the family of all the probability-utility pairs that represent a given desirability relation.