On the Computation of Equilibria in Discrete First-Price Auctions

Fuente: arXiv
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Autori principali: Filos-Ratsikas, Aris, Giannakopoulos, Yiannis, Hollender, Alexandros, Kokkalis, Charalampos
Natura: Preprint
Pubblicazione: 2024
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author Filos-Ratsikas, Aris
Giannakopoulos, Yiannis
Hollender, Alexandros
Kokkalis, Charalampos
author_facet Filos-Ratsikas, Aris
Giannakopoulos, Yiannis
Hollender, Alexandros
Kokkalis, Charalampos
contents We study the computational complexity of computing Bayes-Nash equilibria in first-price auctions with discrete value distributions and discrete bidding space, under general subjective beliefs. It is known that such auctions do not always have pure equilibria. In this paper, we prove that the problem of deciding their existence is NP-complete, even for approximate equilibria. On the other hand, it can be shown that mixed equilibria are guaranteed to exist; however, their computational complexity has not been studied before. We establish the PPAD-completeness of computing a mixed equilibrium and we complement this by an efficient algorithm for finding symmetric approximate equilibria in the special case of iid priors. En route to these results, we develop a computational equivalence framework between continuous and discrete first-price auctions, which can be of independent interest, and which allows us to transfer existing positive and negative results from one setting to the other. Finally, we show that correlated equilibria of the auction can be computed in polynomial time.
format Preprint
id arxiv_https___arxiv_org_abs_2402_12068
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the Computation of Equilibria in Discrete First-Price Auctions
Filos-Ratsikas, Aris
Giannakopoulos, Yiannis
Hollender, Alexandros
Kokkalis, Charalampos
Computer Science and Game Theory
Computational Complexity
We study the computational complexity of computing Bayes-Nash equilibria in first-price auctions with discrete value distributions and discrete bidding space, under general subjective beliefs. It is known that such auctions do not always have pure equilibria. In this paper, we prove that the problem of deciding their existence is NP-complete, even for approximate equilibria. On the other hand, it can be shown that mixed equilibria are guaranteed to exist; however, their computational complexity has not been studied before. We establish the PPAD-completeness of computing a mixed equilibrium and we complement this by an efficient algorithm for finding symmetric approximate equilibria in the special case of iid priors. En route to these results, we develop a computational equivalence framework between continuous and discrete first-price auctions, which can be of independent interest, and which allows us to transfer existing positive and negative results from one setting to the other. Finally, we show that correlated equilibria of the auction can be computed in polynomial time.
title On the Computation of Equilibria in Discrete First-Price Auctions
topic Computer Science and Game Theory
Computational Complexity
url https://arxiv.org/abs/2402.12068