Agri-environmental auctions with synergies

Auctions are increasingly used in agri-environmental contracting. However, the issue of synergy effect between agri-environmental measures has been consistently overlooked, both by decision-makers and by the theoretical literature on conservation auction. Based on laboratory experiments, the objective of this paper is to compare the performance of different procurement auction designs (simultaneous, sequential and combinatorial) in the case of multiple heterogeneous units where bidders may potentially want to sell more than one unit and where their supply cost structure displays positive synergies. The comparison is made by using two performance criteria: budget efficiency and allocative efficiency. We also test if performance results are affected by information feedback to bidders after each auction period. Finally we explain performance results by the analysis of bidding behaviour in the three mechanisms.

Computing Stable Coalitions: Approximation Algorithms for Reward Sharing

Consider a setting where selfish agents are to be assigned to coalitions or projects from a fixed set P. Each project k is characterized by a valuation function; v_k(S) is the value generated by a set S of agents working on project k. We study the following classic problem in this setting: "how should the agents divide the value that they collectively create?". One traditional approach in cooperative game theory is to study core stability with the implicit assumption that there are infinite copies of one project, and agents can partition themselves into any number of coalitions. In contrast, we consider a model with a finite number of non-identical projects; this makes computing both high-welfare solutions and core payments highly non-trivial. The main contribution of this paper is a black-box mechanism that reduces the problem of computing a near-optimal core stable solution to the purely algorithmic problem of welfare maximization; we apply this to compute an approximately core stable solution that extracts one-fourth of the optimal social welfare for the class of subadditive valuations. We also show much stronger results for several popular sub-classes: anonymous, fractionally subadditive, and submodular valuations, as well as provide new approximation algorithms for welfare maximization with anonymous functions. Finally, we establish a connection between our setting and the well-studied simultaneous auctions with item bidding; we adapt our results to compute approximate pure Nash equilibria for these auctions.Comment: Under Revie

Composable and Efficient Mechanisms

We initiate the study of efficient mechanism design with guaranteed good properties even when players participate in multiple different mechanisms simultaneously or sequentially. We define the class of smooth mechanisms, related to smooth games defined by Roughgarden, that can be thought of as mechanisms that generate approximately market clearing prices. We show that smooth mechanisms result in high quality outcome in equilibrium both in the full information setting and in the Bayesian setting with uncertainty about participants, as well as in learning outcomes. Our main result is to show that such mechanisms compose well: smoothness locally at each mechanism implies efficiency globally. For mechanisms where good performance requires that bidders do not bid above their value, we identify the notion of a weakly smooth mechanism. Weakly smooth mechanisms, such as the Vickrey auction, are approximately efficient under the no-overbidding assumption. Similar to smooth mechanisms, weakly smooth mechanisms behave well in composition, and have high quality outcome in equilibrium (assuming no overbidding) both in the full information setting and in the Bayesian setting, as well as in learning outcomes. In most of the paper we assume participants have quasi-linear valuations. We also extend some of our results to settings where participants have budget constraints

Allocation in Practice

How do we allocate scarcere sources? How do we fairly allocate costs? These are two pressing challenges facing society today. I discuss two recent projects at NICTA concerning resource and cost allocation. In the first, we have been working with FoodBank Local, a social startup working in collaboration with food bank charities around the world to optimise the logistics of collecting and distributing donated food. Before we can distribute this food, we must decide how to allocate it to different charities and food kitchens. This gives rise to a fair division problem with several new dimensions, rarely considered in the literature. In the second, we have been looking at cost allocation within the distribution network of a large multinational company. This also has several new dimensions rarely considered in the literature.Comment: To appear in Proc. of 37th edition of the German Conference on Artificial Intelligence (KI 2014), Springer LNC

Taking the Lab to the Field: Experimental Tests of Alternative Mechanisms to Procure Multiple Contracts

The first part of the paper reports the results from a sequence of laboratory experiments comparing the bidding behavior for multiple contracts in three different sealed bid auction mechanisms; first-price simultaneous, first-price sequential and first-price combinatorial bidding. The design of the experiment is based on experiences from a public procurement auction of road markings in Sweden. Bidders are asymmetric in their cost functions; some exhibit decreasing average costs of winning more than one contract, whereas other bidders have increasing average cost functions. The combinatorial bidding mechanism is demonstrated to be most efficient. The second part of the paper describes how the lab experiment was followed up by a field test of a combinatorial procurement auction of road markings.Multiple units, non-constant costs, asymmetric redemption values, alternative procurement mechanisms

Corruption and Collusion in Procurement Tenders

There is a mounting body of evidence that collusive agreements between bidders in large multiple-object procurement tenders are often supported by a corrupt administrator. In a first-price multiple-object auction, if the auctioneer has some legal discretion to allow bidders to readjust their offers prior to the official opening, he also has incentives to extract bribes from agents in exchange for abusing this discretion. In particular, corrupt agent’s incentives to receive bribes are closely linked with that of creating a ’bidding ring’ as the agent’s discretionary power gains value when firms collude. Thus, corruption generates focal equilibria where bidders fully refrain from competing with each other. Additional flexibility of the auction format such as the possibility to submit package bids, which is often considered to be efficiency-enhancing in theoretical literature, increases the risk of collusion in the presence of corruption. Such problems are more likely to arise in tenders, where participating firms are not too close competitors.auctions, corruption, collusion

Collusive market-sharing and corruption in procurement

This paper investigates links between corruption and collusion in procurement. A first-price multiple-object auction is administered by an agent who has legal discretion to allow for a readjustment of (all) submitted offers before the official opening. The agent may be corrupt, i.e. willing to "sell" his decision in exchange for a bribe. Our main result shows that the corrupt agent's incentives to extract rents are closely linked with that of a cartel of bidders. First, collusive bidding conveys value to the agent's decision power. Second, self-interested abuse of discretion to extract rents (corruption) provides a mechanism to enforce collusion. A second result is that package bidding can facilitate collusion. We also find that with corruption, collusion is more likely in auctions where firms are small relative to the market. Our main message to auction designers, competition authorities and criminal courts is that risks of collusion and of corruption must be addressed simultaneously. Some other policy implications for the design of tender procedures are discussed.auction ; corruption ; collusion

Proving soundness of combinatorial Vickrey auctions and generating verified executable code

Using mechanised reasoning we prove that combinatorial Vickrey auctions are soundly specified in that they associate a unique outcome (allocation and transfers) to any valid input (bids). Having done so, we auto-generate verified executable code from the formally defined auction. This removes a source of error in implementing the auction design. We intend to use formal methods to verify new auction designs. Here, our contribution is to introduce and demonstrate the use of formal methods for auction verification in the familiar setting of a well-known auction

Combinatorial versus sequential auctions to allocate PPP highway projects

This article models a procurement process for allocating multiple related public-private partnership (PPP) highway projects. Traditionally, public infrastructure procurement processes have used a sequential allocation mechanism, despite the potential benefits of allocating all projects at once. The main contribution of this research is to address the question whether these projects should be auctioned individually, in sequential auctions, or at the same time, in a combinatorial auction. Our goal is to understand the impact of the allocation process in terms of efficiency and social welfare. In sequential auctions, bidders submit their offers for each project independently. However, in combinatorial auctions, contractors have the ability to bid for their preferred packages (combinations of projects), reflecting synergies or entry costs, if any, in their valuations. We have compared the impact in terms of efficient allocation and social welfare of both mechanisms in order to help policymakers to take future decisions when facing these processes. The methodology used to address these core questions in the multidisciplinary environment described is based on social simulations, which involves conducting analysis by means of computational simulations. For this work we have created a sophisticated valuation model adapted to the public infrastructure sector and we have developed a simulator which includes multiple types of bidders, projects and several scenarios. The experimental setup is based on the second wave of the Colombian 4G program, a case involving the allocation of 9 highway construction projects across the country. We have also included references to multiple examples of real markets in which these mechanisms could be implemented. Therefore, this research provides a valuable reference for policymakers chasing to enhance market design that could be applied in many real-world scenarios. The results reveal that the combinatorial mechanism improves the process in terms of optimal allocation and efficiency, yielding significant savings for all parties