Isa has joined the Economics Discipline Group in 2017. He has received his PhD in economics from Penn State University in 2007 and has held academic positions at Carnegie Mellon University.
Associate Editor, Review of Economic Design, June 2013 - Present
Can supervise: YES
Isa's research interests are in the areas of microeconomic theory and game theory in general, and in market design, mechanism design, auction theory and matching theory in particular.
We consider multi-unit discriminatory auctions where ex ante symmetric bidders have single-unit demands and resale is allowed after the bidding stage. When bidders use the optimal auction to sell items in the resale stage, the equilibrium in the auction without resale is no longer an equilibrium in an auction with resale. We find a symmetric and monotone equilibrium when there are two units for sale, and, interestingly, we show that there may not be a symmetric and monotone equilibrium if there are more than two units.
Hafalir, IE, Hakimov, R, Kuebler, D & Kurino, M 2018, 'College admissions with entrance exams: Centralized versus decentralized', JOURNAL OF ECONOMIC THEORY, vol. 176, pp. 886-934.View/Download from: Publisher's site
We examine the effect of the presence of expert buyers on other buyers, the platform, and the sellers in online markets. We model buyer expertise as the ability to accurately predict the quality, or condition, of an item, modeled as its common value. We show that nonexperts may bid more aggressively, even above their expected valuation, to compensate for their lack of information. As a consequence, we obtain two interesting implications. First, auctions with a “hard close” may generate higher revenue than those with a “soft close.” Second, contrary to the linkage principle, an auction platform may obtain a higher revenue by hiding the item’s common-value information from the buyers. We also consider markets where both auctions and posted prices are available and show that the presence of experts allows the sellers of high-quality items to signal their quality by choosing to sell via auctions.
We offer a theoretical and empirical comparison of auctions and negotiatedsales. We ﬁrst build a simple model to show that auctions generate a higherrelative price than negotiated sales when demand for the asset is strong,when the asset is more homogeneous and when the asset attracts buyerswith higher valuations. Using data from property sales in Singapore, we ﬁndsupport for our theoretical predictions. In addition, we ﬁnd that auctions do notnecessarily generate a higher price premium for foreclosed properties than fornonforeclosed properties.
In a stylized environment with complementary products, we study a class of dominant strategy implementable direct mechanisms and focus on the objective of minimizing the expected surplus from core deviations. For this class of mechanisms, we formulate the core deviation minimization problem as a calculus of variations problem and numerically solve it for some interesting special cases. We then compare the core deviation surplus in the optimal auction (CDMA) to that in Vickrey-Clark-Groves mechanism (VCG) and core-selecting auctions (CSAs). We find that the expected surplus from core deviations can be significantly smaller in CDMA than that in both VCG and CSAs.
Ehlers, L, Hafalir, IE, Yenmez, MB & Yildirim, MA 2014, 'School choice with controlled choice constraints: Hard bounds versus soft bounds', JOURNAL OF ECONOMIC THEORY, vol. 153, pp. 648-683.View/Download from: Publisher's site
The prevalent affirmative action policy in school choice limits the number of admitted majority students to give minority students higher chances to attend their desired schools. There have been numerous efforts to reconcile affirmative action policies with celebrated matching mechanisms such as the deferred acceptance and top trading cycles algorithms. Nevertheless, it is theoretically shown that under these algorithms, the policy based on majority quotas may be detrimental to minorities. Using simulations, we find that this is a more common phenomenon rather than a peculiarity. To circumvent the inefficiency caused by majority quotas, we offer a different interpretation of the affirmative action policies based on minority reserves. With minority reserves, schools give higher priority to minority students up to the point that the minorities fill the reserves. We compare the welfare effects of these policies. The deferred acceptance algorithm with minority reserves Pareto dominates the one with majority quotas. Our simulations, which allow for correlations between student preferences and school priorities, indicate that minorities are, on average, better off with minority reserves while adverse effects on majorities are mitigated.
In a setup where a divisible good is to be allocated to a set of bidders with budget constraints, we introduce a mechanism in the spirit of the Vickrey auction. In the mechanism we propose, understating budgets or values is weakly dominated. Since the revenue is increasing in budgets and values, all kinds of equilibrium deviations from true valuations turn out to be beneficial to the auctioneer. We also show that ex-post Nash equilibrium of our mechanism is near Pareto optimal in the sense that all full winnersʼ values are above all full losersʼ values
Hafalir, I & Krishna, V 2009, 'Revenue and efficiency effects of resale in first-price auctions', JOURNAL OF MATHEMATICAL ECONOMICS, vol. 45, no. 9-10, pp. 589-602.View/Download from: Publisher's site