Method for cold start of a multi-armed bandit in a recommender system

Smriti Bhagat and Stéphane Caron. US Patent Application US-20150012345-A1.


I'm not proud of this software patent application. The patent system stems from a laudable principle: incenting companies to disclose technological knowledge, lest it is lost if the company shuts down. Yet patent systems have turned into an arms race where companies files both "offensive" and "defensive" patents in preparation for or to prevent lawsuits. Not to mention the long-running issue of patent trolls. This war is not about technological advancement, which it mostly harms, but about monopoly consolidation. Open source licenses provide a high-tech détente out of this.


A method performed by a recommender system to recommend items to a new user includes calculating reward estimates from multiple multi-armed bandit models of a user and her social network friends. The new user's social network friends have multi-armed bandit models that are well established. The mixed multi-armed bandit estimates are processed to select the arm that maximizes the estimated reward to the new user. The multi-armed bandit arm of the greatest reward estimate is played and the new user responds by providing feedback so that the new user's multi-armed bandit model is updated as time progresses.


  title = {Method for cold start of a multi-armed bandit in a recommender system},
  author = {Smriti Bhagat and St{\'e}phane Caron},
  year = {2015},
  month = jan,
  note = {US Patent App. 14/308,044},
  url = {},


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