Dominant-strategy truthfulness is traditionally considered the best possible solution concept in mechanism design, as it enables one to predict with confidence which strategies INDEPENDENT players will actually choose. Yet, as with any other form of equilibrium, it too can be extremely vulnerable to COLLUSION. The problem of collusion is particularly evident for UNRESTRICTED combinatorial auctions}, arguably the hardest type of auctions.We thus investigate how much revenue can be guaranteed, in unrestricted combinatorial auctions, by dominant-strategy-truthful mechanisms that are COLLUSION-RESILIENT in a very strong sense; and obtain almost matching upper- and lower-bounds.
