“…The second family of solutions hides the content from undesired audiences, for instance, hiding family related content from friends in the colleague circle. To determine the 'undesired audiences', earlier studies relied on computational approaches to automate privacy decisions such as novel access-control models [49-52, 123, 129], recommender systems [35,36], adaptive audience recommendations [114,115], aggregated voting [19,104,119], a collaborative access-control system based on secret sharing [12], trust-based consent collection [2], and mechanisms for supporting co-owners' interactions in negotiating privacy settings [58,59,101]. Some of these studies were built upon theories such as the use of game theory for negotiation [101,118], argumentation theory [35,37,63,88,90], and human-values theory [88][89][90].…”