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The ranking game

In the web, page creators often compete for their ranking on relevant search queries, as high ranking attracts users and may lead to increased revenues. The positive effect of this competition is that it encourages page owners to improve their content. However, some techniques used for this improvement, such as keyword stuffing, are considered harmful. Current search engine literature largely ignores the interplay between the retrieval system and the pages' content evolvement. This paper studies the above phenomenon. We model pages as strategic players, competing for a better rank by content manipulations, while the search engine controls the ranking mechanism. We show that such competition may degrade retrieval effectiveness as irrelevant pages tend to outrank better ones. Further, we investigate how the search engine's choice of a ranking scheme may reduce the incentive to manipulate the page content. Finally, we propose a novel ranking solution that empirically minimizes the adverse effect on a real dataset.