Recommender systems are now commonplace - we have films, music and hotels ‘chosen’ for us by artificial intelligence. It is not enough, however, for recommendations to be accurate or relevant. In many domains, recommendations must be novel to the user or 'serendipitous' (serendipity in the context of recommender systems means recommending items to users that will be accurate and surprise the user, valuable or pleasant items that are not looked for ) and a set of recommendations must be diverse. Diversity is one response to uncertainty (what does the user really want?). A recommender cannot be certain of a user's short-term or longer-term interests, both because some user profiles are small and some, while they may not be so small, will contain preferences over different kinds of items. In the face of uncertainty, a diverse set of recommendations is more likely to contain one or more items that will satisfy the user. When a recommender system gives a diverse response, it often scores items for relevance and then ranks them again to balance relevance with diversity. Mesut is working on a specific approach called 'intent-aware diversification'. The idea is that the re-ranked recommendations should cover the different tastes or interests revealed by the user. Most of the existing approaches define user tastes or interests by explicit features of items (for example, 'horror movies'). Masut and the team propose a new intent-aware diversification framework based on user sub-profiles (subsets of the overall user profile), rather than item features. This is advantageous because item features do not necessarily fully represent a user's tastes or interests and are not available in every domain. For example, in the music domain, a user might listen to Indie music in general, but when she wants to relax she listens to Jazz and Blues and when she parties she listens Electronic-Dance. If the recommender always recommends Indie music it can be accurate but it will not satisfy her different interests and tastes. That is why recommender should aim to include some Jazz maybe Electronic-Dance and some other types of music too.