Simultaneous 2nd Price Item Auctions with No-Underbidding

Authors: Michal Feldman, Galia Shabtai5391-5398

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Reproducibility Variable Result LLM Response
Research Type Theoretical We study the price of anarchy (Po A) of simultaneous 2nd price auctions (S2PA) under a new natural condition of no underbidding, meaning that agents never bid on items less than their marginal values. We establish improved (mostly tight) bounds on the Po A of S2PA under no underbidding for different valuation classes (including unit-demand, submodular, XOS, subadditive, and general monotone valuations), in both full-information and incomplete information settings. To derive our results, we introduce a new parameterized property of auctions, termed (γ, δ)-revenue guaranteed, which implies a Po A of at least γ/(1+δ). Via extension theorems, this guarantee extends to coarse correlated equilibria (CCE) in full information settings, and to Bayesian Po A (BPo A) in settings with incomplete information and arbitrary (correlated) distributions. We then show that S2PA are (1, 1)-revenue guaranteed with respect to bids satisfying no underbidding. This implies a Po A of at least 1/2 for general monotone valuation, which extends to BPOA with arbitrary correlated distributions. Moreover, we show that (λ, µ)-smoothness combined with (γ, δ)-revenue guaranteed guarantees a Po A of at least (γ + λ)/(1 + δ + µ). This implies a host of results, such as a tight Po A of 2/3 for S2PA with submodular (or XOS) valuations, under no overbidding and no underbidding.
Researcher Affiliation Academia Michal Feldman and Galia Shabtai Tel Aviv University michal.feldman@cs.tau.ac.il, galiashabtai@gmail.com
Pseudocode No The paper does not contain structured pseudocode or algorithm blocks.
Open Source Code No The paper states: "*For the full version, see https://arxiv.org/abs/2003.11857 (Feldman and Shabtai 2020)." This link refers to the full version of the paper itself, not source code for the methodology.
Open Datasets No The paper is theoretical and does not use datasets for training or evaluation.
Dataset Splits No The paper is theoretical and does not describe data splits for validation.
Hardware Specification No The paper is theoretical and does not describe running experiments, so no hardware specifications are provided.
Software Dependencies No The paper is theoretical and does not describe running experiments, so no software dependencies are provided.
Experiment Setup No The paper is theoretical and does not describe any experimental setup or training configurations.