Model checking bidding behaviors in internet concurrent auctions

Online auctions have become a quite popular and effective approach in the Internet-based eMarketplace. In concurrent auctions, where multiple auctions for identical items are running simultaneously, users’ bidding behaviors become very complicated. This situation motivates shilling behaviors, in which a seller disguises himself as normal bidders in order to drive up the bidding price and make the winning bidder pay more for an auctioned item. The goal of this paper is to propose a formal approach to verifying bidding behaviors, and especially, detecting shilling behaviors in concurrent online auctions. We develop a model template for concurrent auctions and derive auction models based on auction data from two concurrent auctions. The auction model can be formally verified using the SPIN model checker for certain behavioral properties, which are specified in pattern-based LTL (Linear Temporal Logic) formulas. To illustrate the feasibility and effectiveness of our approach, we provide a case study to show how possible shill bidders can be detected.