Баранов Олег Валерьевич

The VCG Mechanism, the Core, and Assignment Stages in Auctions

2026 в печати · ARTICLE · en

The Vickrey-Clarke-Groves (VCG) mechanism is one of the most compelling constructs in mechanism design, but the presence of complementary goods creates the possibility of non-core and even zero-revenue outcomes. In this article, we show that joint feasibility constraints on allocations offer a second pathway to ill-behaved outcomes in the VCG mechanism, even when all bidders have substitutes preferences for the goods. We then develop a theory of complementarities specifically tailored to assignment stages of spectrum auctions. Assignment stages typically guarantee contiguous spectrum to each winner—this proves to be an especially severe joint feasibility constraint. We propose a definition of bidder complementarities and further dichotomize them as direct or indirect. When opponents bid on distinct parts of a bidder’s preferred assignment, they set up a direct bidder complementarity. However, if an assignment is denied through the contiguity restriction, that is called an indirect complementarity. As a result, non-core outcomes, together with all of the accompanying anomalies, can be expected in VCG assignment stages. We then examine a conspicuous recent spectrum auction, the FCC’s Broadcast Incentive Auction, and we provide the first documentation of zero-revenue outcomes in the field. Of 207 assignment stage auctions with at least three bidders, 17.9% produced non-core outcomes relative to the bids and, of these, 3 generated zero revenues. After rescaling bidder values, we find that the majority of assignment stage auctions had the potential for exploitable bidder complementarities and that the vast majority of bidder complementarities—both potential and realized—were indirect.

Core-Selecting Auctions with Incomplete Information

2020 · ARTICLE · en

Core-selecting auctions were proposed as alternatives to the VickreyClarke-Groves (VCG) mechanism for environments with complementarities. In this paper, we consider a simple incomplete-information model that allows correlations among bidders’ values. We perform a full equilibrium analysis of three core-selecting auction formats as applied to the “local-local-global” model. We show that seller revenues and efficiency from core-selecting auctions can improve as correlations among bidders’ values increase, producing outcomes that are closer to the true core than are the VCG outcomes. Thus, there may be a theoretical justification for policymakers to utilize core-selecting auctions rather than the VCG mechanism in certain environments.

Revealed Preference and Activity Rules in Dynamic Auctions

2020 · ARTICLE · en

Activity rules—constraints that limit bidding in future rounds based on past bids—are intended to limit strategic bidding delays in high-stakes auctions. This article provides a general treatment of activity rules. Traditional point-based rules are effective for homogeneous goods and reasonably suited for substitute goods. However, they are simultaneously too strong and too weak for general environments; they allow parking, while sometimes preventing straightforward bidding. We prove that the activity rule operationalizing the generalized axiom of revealed preference (GARP) is essentially the unique rule that enforces the Law of Demand while enabling straightforward bidding and never producing “dead ends.”

An Efficient Ascending Auction for Private Valuations

2018 · ARTICLE · en

Known dynamic implementations of the Vickrey–Clarke–Groves mechanism in general private-value auction settings utilize non-linear (not additively-separable over goods) and non-anonymous (bidder-specific) prices. The need for non-linear and non-anonymous prices — a complication that is often difficult to implement in practice — arises from limiting attention to elicitation processes based on demand queries (i.e., asking bidders to report their demands at posted prices). In this paper, we relax this restriction and allow the auctioneer to supplement demand queries with marginal value queries (i.e., requests to report value differences between pairs of commodity bundles) as needed. This added flexibility enables an iterative ascending auction design that achieves efficiency despite using linear and anonymous prices.

Efficient Procurement Auctions with Increasing Returns

2017 · ARTICLE · en

For procuring from sellers with decreasing returns, there are known efficient dynamic auction formats. In this paper, we design an efficient dynamic procurement auction for the case where goods are homogeneous and bidders have increasing returns. Our motivating example is the procurement of vaccines, which often exhibit large fixed costs and small constant marginal costs. The auctioneer names a price and bidders report the interval of quantities that they are willing to sell at that price. The process repeats with successively lower prices, until the efficient outcome is discovered. We demonstrate an equilibrium that is efficient and generates VCG prices.

A Practical Guide to the Combinatorial Clock Auction

2017 · ARTICLE · en

The combinatorial clock auction (CCA) is an important recent innovation in auction design that has been utilised for many spectrum auctions worldwide. While the theoretical foundations of the CCA are described in a growing literature, many of the practical implementation choices are neglected. In this article, we examine some of the most critical practical decisions for a regulator implementing the CCA. Topics include: implementation of reserve prices; endogenous band plans; supplementary round activity rules; competition policy; bidding languages; and allocation of the core burden. We illustrate our discussion with examples from recent spectrum auctions that used the CCA format.

Market Design and the Evolution of the Combinatorial Clock Auction

2014 · ARTICLE · en