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The Dynamics of Auctions with Learning Agents

Explore how learning agents impact auction strategies and revenue outcomes.

Gagan Aggarwal, Anupam Gupta, Andres Perlroth, Grigoris Velegkas

― 6 min read


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Auctions have always been a game of chance and strategy. Each bidder tries to outsmart the others, hoping to walk away with the best deal. But what happens when the players in this game are not just people but Learning Agents? Imagine robots and algorithms trying to figure out how to bid without ever actually telling the truth about their worth. The landscape changes completely.

In our exploration of auctions, we focus on how learning agents behave over time in repeated auctions. In particular, we dive into how these agents can sometimes miss the mark when it comes to bidding truthfully, even in auctions meant to encourage honesty.

Learning Agents in Auctions

Let’s picture a second-price auction, a type where the highest bidder wins but pays the second-highest bid. Seems simple, right? Well, when you throw in learning agents-bidders that adjust their strategies based on past performance-the situation starts to get complicated. These agents are supposed to learn from their experiences but might take errant paths along the way.

Surprisingly, even though they “learn,” they might not end up bidding what they truly value the item at. Instead of converging to truthful bidding behavior, they may stick to their own flawed strategies until they learn the hard way-a classic case of two steps forward, one step back.

Revenue Maximization Dilemma

Now, think about the auctioneer, the one running the show. Their goal is to maximize revenue. In traditional settings with rational bidders, they could use a second-price auction with a reserve price to rake in the most cash. But when learning bidders enter the fray, things get tricky.

Randomized Auctions, which might seem like a bad idea at first glance, could actually offer better revenue than the tried-and-true second-price auction with reserves. By mixing things up, the auctioneer can ensure they don’t miss out on the potential revenue that learning agents might generate. It’s a bit like mixing your favorite drinks and finding a new cocktail that you didn't expect to enjoy.

The Mechanism of Auctions

To understand this chaos better, let’s break down how these auctions work in simpler terms. We’re focusing on single-item auctions, where two bidders repeatedly participate using a learning algorithm. Both participants have values that stay pretty much the same over time, which is a common scenario in many online selling platforms today.

Picture this: Every time the auction happens, both bidders use their learning algorithms to adjust their bids. They might have good intentions, but if their Learning Rates are mismatched, trouble can arise. If one bidder learns quicker than the other, it can create a situation where one agent learns to bid too low, leading to lower overall revenues.

Randomization: A Game Changer

This is where randomization comes into play. Randomized auctions can genuinely improve the odds of revenue maximization. It turns out that introducing a bit of randomness can help guide those lower-bidding agents toward bidding more in line with their true values.

To put it differently, randomness is like that friend who brings some unpredictability to your otherwise boring game night-suddenly, things are lively and fun! The auctioneer must carefully blend this randomness with truthful bidding to get bidders to come out of their shells and play the game properly.

The Role of Learning Rates

Yet, let’s not forget about learning rates. This aspect is crucial because it determines how fast or slow agents adapt their strategies. If the agent with the better value learns more slowly than the other, they may find themselves bidding suboptimally. Imagine a race where one runner is allowed to adjust their speed every lap, while another is stuck in their slow lane.

In many cases, if both agents are learning at the same speed, the one with the lower initial value will struggle to catch up in the bidding game.

Understanding Convergence

In the auctions we study, we want to see how quickly and effectively these agents can learn to bid truthfully. Convergence here means that over time, their bids will gradually align with their actual valuations. This is the golden path-the ideal outcome.

The challenge is that depending on their learning rates, they may or may not get there. The second-price auction might provide instant feedback, ensuring bidders can learn quickly, but if they aren’t careful or if the auction is set up poorly, they may end up making the same mistakes repeatedly.

Implications of Mixed Strategies

With all this in mind, mixed auctions-those that incorporate elements of randomness-are worth considering more seriously. Imagine you’re at a buffet. Sometimes, mixing a little bit of everything leads to magical flavor combinations, much like how mixing auction strategies can lead to better outcomes.

It is also essential that these auctions remain truthful. Each agent should feel confident that their best strategy is to bid their true valuation. After all, if every agent is honest, it creates a level playing field, ensuring better outcomes for everyone.

The Regret of the Auctioneer

One last thought: What if the auctioneer must maintain consistent auction rules across multiple rounds? They will face what we call auctioneer regret. This regret measures how much revenue could be missed compared to a perfect scenario.

In simple terms, if the auctioneer decides on a fixed strategy that doesn’t adapt to the learning agents, they might see their revenue take a hit. Like a chef who insists on using the same recipe without adjusting for seasonal ingredients-sometimes, a little flexibility is needed to thrive.

Conclusion

Ultimately, our exploration highlights the unique dynamics of auctions involving learning agents. The interplay between learning rates and randomized strategies can not only influence bidding behavior but also revenue outcomes. A little randomness might go a long way in creating a more exciting and profitable auction.

So, the next time you think about auctions, consider how learning agents are not just in it to win but are also learning all the time. And who knows, maybe a bit of randomness will lead to a jackpot for everybody involved.

Original Source

Title: Randomized Truthful Auctions with Learning Agents

Abstract: We study a setting where agents use no-regret learning algorithms to participate in repeated auctions. \citet{kolumbus2022auctions} showed, rather surprisingly, that when bidders participate in second-price auctions using no-regret bidding algorithms, no matter how large the number of interactions $T$ is, the runner-up bidder may not converge to bidding truthfully. Our first result shows that this holds for \emph{general deterministic} truthful auctions. We also show that the ratio of the learning rates of the bidders can \emph{qualitatively} affect the convergence of the bidders. Next, we consider the problem of revenue maximization in this environment. In the setting with fully rational bidders, \citet{myerson1981optimal} showed that revenue can be maximized by using a second-price auction with reserves.We show that, in stark contrast, in our setting with learning bidders, \emph{randomized} auctions can have strictly better revenue guarantees than second-price auctions with reserves, when $T$ is large enough. Finally, we study revenue maximization in the non-asymptotic regime. We define a notion of {\em auctioneer regret} comparing the revenue generated to the revenue of a second price auction with truthful bids. When the auctioneer has to use the same auction throughout the interaction, we show an (almost) tight regret bound of $\smash{\widetilde \Theta(T^{3/4})}.$ If the auctioneer can change auctions during the interaction, but in a way that is oblivious to the bids, we show an (almost) tight bound of $\smash{\widetilde \Theta(\sqrt{T})}.$

Authors: Gagan Aggarwal, Anupam Gupta, Andres Perlroth, Grigoris Velegkas

Last Update: 2024-11-14 00:00:00

Language: English

Source URL: https://arxiv.org/abs/2411.09517

Source PDF: https://arxiv.org/pdf/2411.09517

Licence: https://creativecommons.org/licenses/by/4.0/

Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.

Thank you to arxiv for use of its open access interoperability.

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