document: Online allocation of display ads with smooth delivery Display ads on the Internet are often sold in bundles of thousands or millions of impressions over a particular time period , typically weeks or months . Ad serving systems that assign ads to pages on behalf of publishers must satisfy these contracts , but at the same time try to maximize overall quality of placement . This is usually modeled in the literature as an online allocation problem , where contracts are represented by overall delivery constraints over a finite time horizon . However this model misses an important aspect of ad delivery : time homogeneity . Advertisers who buy these packages expect their ad to be shown smoothly throughout the purchased time period , in order to reach a wider audience , to have a sustained impact , and to support the ads they are running on other media ( e.g. , television ) . In this paper we formalize this problem using several nested packing constraints , and develop a tight ( 1-1 \/ e ) - competitive online algorithm for this problem . Our algorithms and analysis require novel techniques as they involve online computation of multiple dual variables per ad . We then show the effectiveness of our algorithms through exhaustive simulation studies on real data sets .
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