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TL;DR

VCG Mechanism and Incentive Compatibility: A canonical quantitative trading interview question at olympiad difficulty. Commonly asked at Two Sigma, DE Shaw, Citadel.

By Valenke Exam Prep Team·Last updated 2026-06-01
olympiadAlgorithmic Game Theory

VCG Mechanism and Incentive Compatibility

Asked at: Two Sigma, DE Shaw, Citadel

Problem
In a combinatorial auction with mm items and nn bidders, the Vickrey-Clarke-Groves (VCG) mechanism charges each winner their "externality" — the harm they cause to other bidders by participating. Prove that truthful reporting of values is a dominant strategy in VCG. Compute VCG payments for a simple 2-item, 3-bidder example.

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