Notice of RetractionOptimal keyword auctions withvariable costs of advertisement

Notice of Retraction

After careful and considered review of the content of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE´s Publication Principles.

We hereby retract the content of this paper. Reasonable effort should be made to remove all past references to this paper.

The presenting author of this paper has the option to appeal this decision by contacting TPII@ieee.org.

This paper characterizes optimal keyword auction mechanism, obtains Revenue Equivalence Theorem for keyword auctions and designs a kind of optimal keyword auction mechanism by considering the variable costs of advertisement positions. Under assumptions that the valuation of advertisement position to the advertiser is independently identically distributed, that the click-through rate depends only on advertisement positions and per-click variable costs are non-decreasing, we obtain the explicit expressions for the allocation rules and payment rules of a optimal mechanism, which is a generalization of traditional VCG mechanism.