arXiv subjects

Van-Quy Nguyen

Publications and source records attributed to Van-Quy Nguyen.

4 recordsLinked to original sources

arXiv2026

Rating Manipulation: Credibility Inversion and Audit Leakage

Online ratings turn a long review history into one public number. This makes sellers easier to compare, but it also gives them a single clear target to manipulate. We study a low-quality seller who can add fake reviews carrying different scores, buyers who infer quality from the displayed average, and a platform that can target particular scores for enforcement. The model separates the rating buyers see from the hidden mix of reviews used to produce it, and the two need not move together. An almost-perfect rating can be less credible than a slightly lower one when low-quality sellers are especially likely to manufacture the top of the scale, so a seller whose buyers become more valuable may display less and sell more. At a fixed displayed rating, targeted enforcement can redirect fake reviews toward other scores rather than eliminate manipulation; buyers do not see this substitution because the displayed average is unchanged. Raw ratings therefore provide only a partial picture of credibility and enforcement, and buyer-oriented ranking should account for what a rating conveys, not only its numerical level.

econ.TH↗

arXiv2026

Spectral Aggregation of Quantile Preferences

Many collective decisions under risk are made by people who care about different parts of the outcome distribution: downside losses, typical performance, or upside gains. This paper models this disagreement with quantile preferences and studies how the represented quantile levels can be aggregated. Our main result is a spectral support theorem: a spectral social aggregation satisfies the Pareto principle if and only if its social spectrum puts mass only on quantile levels represented in society. Hence, Pareto consistency makes representative-quantile aggregation a dictatorial case. In addition, we derive spectral aggregation from rank-based axioms, develop finite and threshold-Pareto consequences, and show when local benchmark-affine and elliptical common-shape domains admit a representative-quantile reduction.

econ.TH↗

arXiv2024

Hoping for the best while preparing for the worst in the face of uncertainty

We propose and axiomatize a new model of incomplete preferences under uncertainty, hope-and-prepare preferences: one act is preferred to another if and only if both its optimistic evaluation -- the welfare level attained in the best-case scenario-- and its pessimistic evaluation --the welfare level attained in the worst-case scenario-- rank it above the other. Both evaluations are computed over sets of probability distributions. We make the case that, compared to existing incomplete criteria under ambiguity, hope-and-prepare preferences address the trade-off between conviction and decisiveness in a new way, which is more favorable to decisiveness. We characterize a completion of an incomplete hope-and-prepare preference relation admitting an (asymmetric) $\alpha$-\textit{maxmin expected utility} representation, in which $\alpha$ is unique. Conversely, given a standard $\alpha$-MEU preference and a fixed value of $\alpha$, we recover the concordant hope-and-prepare preference that it completes.

econ.TH↗

arXiv2024

Strategic formation of production networks

We provide a strategic model of the formation of production networks that subsumes the standard general equilibrium approach. The objective of firms in our setting is to choose their supply relationships so as to maximize their profit at the general equilibrium that unfolds. We show that this objective is equivalent to the maximization by the firms of their eigenvector centrality in the production network. As is common in network formation games based on centrality, there are multiple Nash equilibria in our setting. We have investigated the characteristics and the social efficiency of these equilibria in a stylized version of our model representing international trade networks. We show that the impact of network structure on social welfare is firstly determined by a trade-off between costs of increasing process complexity and positive spillovers on productivity induced by the diversification of the input mix. We further analyze a variant of our model that accounts for the risks of disruption of supply relationships. In this setting, we characterize how social welfare depends on the structure of the production network, the spatial distribution of risks, and the process of shock aggregation in supply chains. We finally show that simple trade policies characterized by sets of links that are either prevented or catalyzed can be a powerful equilibrium selection device.

econ.TH↗