# Separating the communication complexity of truthful and non-truthful combinatorial auctions

@article{Assadi2020SeparatingTC, title={Separating the communication complexity of truthful and non-truthful combinatorial auctions}, author={Sepehr Assadi and Hrishikesh Khandeparkar and Raghuvansh R. Saxena and S. Matthew Weinberg}, journal={Proceedings of the 52nd Annual ACM SIGACT Symposium on Theory of Computing}, year={2020} }

We prove the first separation in the approximation guarantee achievable by truthful and non-truthful combinatorial auctions with polynomial communication. Specifically, we prove that any truthful auction guaranteeing a (34−1240+є)-approximation for two buyers with XOS valuations over m items requires exp(Ω(ε2 · m)) communication whereas a non-truthful auction by Feige [J. Comput. 2009] is already known to achieve a 34-approximation in (m) communication. We obtain our lower bound for truthful…

## 6 Citations

Improved truthful mechanisms for combinatorial auctions with submodular bidders

- Computer ScienceSIGecom Exch.
- 2020

This work presents a computationally-efficient truthful mechanism with approximation ratio that improves upon the state-of-the-art by almost an exponential factor, and achieves an O((log log m)3)-approximation in expectation, uses only O(n) demand queries, and has universal truthfulness guarantee.

Improved Truthful Mechanisms for Combinatorial Auctions with Submodular Bidders

- Mathematics, Computer Science2019 IEEE 60th Annual Symposium on Foundations of Computer Science (FOCS)
- 2019

This work presents a computationally-efficient truthful mechanism with approximation ratio that improves upon the state-of-the-art by an exponential factor and achieves an O((log logm)^3) -approximation in expectation, uses only O(n) demand queries, and has universal truthfulness guarantee.

The randomized communication complexity of randomized auctions

- Computer ScienceSTOC
- 2021

The authors' lower bounds give the first approximation-resistant, exponential separation between communication complexity of incentivizing vs implementing a Bayesian incentive compatible social choice rule, settling an open question of Fadel and Segal.

Improved Truthful Mechanisms for Subadditive Combinatorial Auctions: Breaking the Logarithmic Barrier

- Computer Science, MathematicsSODA
- 2021

We present a computationally-efficient truthful mechanism for combinatorial auctions with subadditive bidders that achieves an $O((\log\!\log{m})^3)$-approximation to the maximum welfare in…

Exponential communication separations between notions of selfishness

- Computer Science, EconomicsSTOC
- 2021

We consider the problem of implementing a fixed social choice function between multiple players (which takes as input a type ti from each player i and outputs an outcome f(t1,…, tn)), in which each…

The communication complexity of payment computation

- Computer ScienceSTOC
- 2021

This paper explicitly provides a function f such that ccIC(f)= exp(cc(f) for every f, and shows that if the players are risk-neutral and the can compromise on a randomized truthful-in-expectation implementation (and not on deterministic ex-post implementation) gives that ccTIE(f), for every function f, as long as the domain of f is single parameter or a convex multi-parameter domain.

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