Dueling Over Dessert, Mastering the Art of Repeated Cake Cutting

Fuente: arXiv
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Autori principali: Brânzei, Simina, Hajiaghayi, MohammadTaghi, Phillips, Reed, Shin, Suho, Wang, Kun
Natura: Preprint
Pubblicazione: 2024
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author Brânzei, Simina
Hajiaghayi, MohammadTaghi
Phillips, Reed
Shin, Suho
Wang, Kun
author_facet Brânzei, Simina
Hajiaghayi, MohammadTaghi
Phillips, Reed
Shin, Suho
Wang, Kun
contents We consider the setting of repeated fair division between two players, denoted Alice and Bob, with private valuations over a cake. In each round, a new cake arrives, which is identical to the ones in previous rounds. Alice cuts the cake at a point of her choice, while Bob chooses the left piece or the right piece, leaving the remainder for Alice. We consider two versions: sequential, where Bob observes Alice's cut point before choosing left/right, and simultaneous, where he only observes her cut point after making his choice. The simultaneous version was first considered by Aumann and Maschler (1995). We observe that if Bob is almost myopic and chooses his favorite piece too often, then he can be systematically exploited by Alice through a strategy akin to a binary search. This strategy allows Alice to approximate Bob's preferences with increasing precision, thereby securing a disproportionate share of the resource over time. We analyze the limits of how much a player can exploit the other one and show that fair utility profiles are in fact achievable. Specifically, the players can enforce the equitable utility profile of $(1/2, 1/2)$ in the limit on every trajectory of play, by keeping the other player's utility to approximately $1/2$ on average while guaranteeing they themselves get at least approximately $1/2$ on average. We show this theorem using a connection with Blackwell approachability. Finally, we analyze a natural dynamic known as fictitious play, where players best respond to the empirical distribution of the other player. We show that fictitious play converges to the equitable utility profile of $(1/2, 1/2)$ at a rate of $O(1/\sqrt{T})$.
format Preprint
id arxiv_https___arxiv_org_abs_2402_08547
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Dueling Over Dessert, Mastering the Art of Repeated Cake Cutting
Brânzei, Simina
Hajiaghayi, MohammadTaghi
Phillips, Reed
Shin, Suho
Wang, Kun
Computer Science and Game Theory
Artificial Intelligence
Theoretical Economics
We consider the setting of repeated fair division between two players, denoted Alice and Bob, with private valuations over a cake. In each round, a new cake arrives, which is identical to the ones in previous rounds. Alice cuts the cake at a point of her choice, while Bob chooses the left piece or the right piece, leaving the remainder for Alice. We consider two versions: sequential, where Bob observes Alice's cut point before choosing left/right, and simultaneous, where he only observes her cut point after making his choice. The simultaneous version was first considered by Aumann and Maschler (1995). We observe that if Bob is almost myopic and chooses his favorite piece too often, then he can be systematically exploited by Alice through a strategy akin to a binary search. This strategy allows Alice to approximate Bob's preferences with increasing precision, thereby securing a disproportionate share of the resource over time. We analyze the limits of how much a player can exploit the other one and show that fair utility profiles are in fact achievable. Specifically, the players can enforce the equitable utility profile of $(1/2, 1/2)$ in the limit on every trajectory of play, by keeping the other player's utility to approximately $1/2$ on average while guaranteeing they themselves get at least approximately $1/2$ on average. We show this theorem using a connection with Blackwell approachability. Finally, we analyze a natural dynamic known as fictitious play, where players best respond to the empirical distribution of the other player. We show that fictitious play converges to the equitable utility profile of $(1/2, 1/2)$ at a rate of $O(1/\sqrt{T})$.
title Dueling Over Dessert, Mastering the Art of Repeated Cake Cutting
topic Computer Science and Game Theory
Artificial Intelligence
Theoretical Economics
url https://arxiv.org/abs/2402.08547