Abstract: An online system sends content items for display to client devices associated with users and detects actions associated with the content items performed by the users. The system accesses and applies machine-learning models to predict metrics for a set of users and generates a set of optimal values for the set of users based on the metrics, one or more objectives, and a set of constraints, in which each optimal value indicates whether a user is eligible to be presented with a content item. Responsive to identifying an opportunity to present the content item to a user of the set of users, the system determines whether the user is eligible to be presented with the content item based on an optimal value determined for the user and sends the content item for display to a client device associated with the user if the user is eligible.

Abstract: An online system selects content for placement in positions of a display on a user device. The online system selects a first set of content items according to a first content selection process and a second set of content items according to a second content selection process. To combine the different sets of content items dynamically, the first set of content items and second set of content items are evaluated by a joint impression scoring that includes factors prioritizing user, intrinsic, and other values. The respective contribution by the different factors may be adjusted by one or more adjustable weights, enabling different situations to effect different combinations of content items from the different content selection processes.

Abstract: An online system sends content items for display to client devices associated with users and detects actions associated with the content items performed by the users. The system accesses and applies machine-learning models to predict metrics for a set of users and generates a set of optimal values for the set of users based on the metrics, one or more objectives, and a set of constraints, in which each optimal value indicates whether a user is eligible to be presented with a content item. Responsive to identifying an opportunity to present the content item to a user of the set of users, the system determines whether the user is eligible to be presented with the content item based on an optimal value determined for the user and sends the content item for display to a client device associated with the user if the user is eligible.