Finite liquid-GFT price of anarchy for autobidding-tailored mechanisms

Determine whether non-uIC mechanisms specifically tailored to autobidding can achieve a finite Price of Anarchy for Liquid Gains from Trade in the prior-free two-sided market setting.

Background

The paper proves that broad classes of classical mechanisms that are utility-truthful, individually rational, and weakly budget balanced have unbounded Price of Anarchy for Liquid Gains from Trade when value-maximizing agents participate. The negative results apply to mechanisms such as Trade Reduction and arise because value maximizers can pool their return-on-spend or revenue-over-cost constraints across rounds.

The authors explicitly leave open whether mechanisms that abandon utility-truthfulness and are designed specifically for autobidding can avoid this impossibility and provide a finite liquid-GFT approximation in the prior-free setting. This question is not resolved by the paper's positive liquid-welfare guarantees or its Bayesian first-best mechanism.