How competitive are pay-as-bid auction games?

Fuente: arXiv
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Main Authors: Vanelli, Martina, Como, Giacomo, Fagnani, Fabio
Format: Preprint
Published: 2025
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author Vanelli, Martina
Como, Giacomo
Fagnani, Fabio
author_facet Vanelli, Martina
Como, Giacomo
Fagnani, Fabio
contents We study the pay-as-bid auction game, a supply function model with discriminatory pricing and asymmetric firms. In this game, strategies are non-decreasing supply functions relating pric to quantity and the exact choice of the strategy space turns out to be a crucial issue: when it includes all non-decreasing continuous functions, pure-strategy Nash equilibria often fail to exist. To overcome this, we restrict the strategy space to the set of Lipschitz-continuous functions and we prove that Nash equilibria always exist (under standard concavity assumptions) and consist of functions that are affine on their own support and have slope equal to the maximum allowed Lipschitz constant. We further show that the Nash equilibrium is unique up to the market-clearing price when the demand is affine and the asymmetric marginal production costs are homogeneous in zero. For quadratic production costs, we derive a closed-form expression and we compute the limit as the allowed Lipschitz constant grows to infinity. Our results show that in the limit the pay-as-bid auction game achieves perfect competition with efficient allocation and induces a lower market-clearing price compared to supply function models based on uniform price auctions.
format Preprint
id arxiv_https___arxiv_org_abs_2504_13920
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle How competitive are pay-as-bid auction games?
Vanelli, Martina
Como, Giacomo
Fagnani, Fabio
Optimization and Control
Computer Science and Game Theory
Multiagent Systems
Systems and Control
We study the pay-as-bid auction game, a supply function model with discriminatory pricing and asymmetric firms. In this game, strategies are non-decreasing supply functions relating pric to quantity and the exact choice of the strategy space turns out to be a crucial issue: when it includes all non-decreasing continuous functions, pure-strategy Nash equilibria often fail to exist. To overcome this, we restrict the strategy space to the set of Lipschitz-continuous functions and we prove that Nash equilibria always exist (under standard concavity assumptions) and consist of functions that are affine on their own support and have slope equal to the maximum allowed Lipschitz constant. We further show that the Nash equilibrium is unique up to the market-clearing price when the demand is affine and the asymmetric marginal production costs are homogeneous in zero. For quadratic production costs, we derive a closed-form expression and we compute the limit as the allowed Lipschitz constant grows to infinity. Our results show that in the limit the pay-as-bid auction game achieves perfect competition with efficient allocation and induces a lower market-clearing price compared to supply function models based on uniform price auctions.
title How competitive are pay-as-bid auction games?
topic Optimization and Control
Computer Science and Game Theory
Multiagent Systems
Systems and Control
url https://arxiv.org/abs/2504.13920