8. A system for selecting a relevance function to determine a relevance of a query-content item pair, the system comprising at least one computing processor coupled to a memory, wherein the at least one computing processor is operable to: generate a training set comprising one or more content item-query pairs, the content items-query pairs having a training relevance score assigned by a user; for each query-content item pair, determine a relevance function; modify the relevance function using a loss function according to a relevance score adjustment function that accounts for a query differentiation, wherein the relevance score adjustment function receives the determined relevance function as input, and wherein the query differentiation is a difference between the training relevance score and an output of the relevance score adjustment function; and select a relevance function trained with the query differentiation that produces a smallest loss, when the modified relevance function and the training relevance value converge.
8. A system for selecting a relevance function to determine a relevance of a query-content item pair, the system comprising at least one computing processor coupled to a memory, wherein the at least one computing processor is operable to: generate a training set comprising one or more content item-query pairs, the content items-query pairs having a training relevance score assigned by a user; for each query-content item pair, determine a relevance function; modify the relevance function using a loss function according to a relevance score adjustment function that accounts for a query differentiation, wherein the relevance score adjustment function receives the determined relevance function as input, and wherein the query differentiation is a difference between the training relevance score and an output of the relevance score adjustment function; and select a relevance function trained with the query differentiation that produces a smallest loss, when the modified relevance function and the training relevance value converge. 9. The system of claim 8 wherein using the loss function comprises using the loss function selected from a set of loss functions consisting of a least mean square loss function, a query pairwise loss function and a loss function that compares a desired ranking order with an output ranking order.