Requirements prioritization plays a key role in the requirements engineering process, in particular with respect to critical tasks such as requirements negotiation and software release planning. This paper presents a novel framework which is based on a requirements prioritization process that interleaves human and machine activities, enabling for an accurate prioritization of requirements. Similarly to the Analytic Hierarchy Process (AHP) method, our framework adopts an elicitation process based on the acquisition of pairwise preferences. Differently from AHP, where scalability is a big issue, the framework enables a prioritization process even over a large set of requirements, thanks to the exploitation of machine learning techniques that induce requirements ranking approximations at run time, and to the use of a boolean metrics. Moreover the new approach allows to reduce the bias of a dominance hierarchy, a strategy introduced by AHP to deal with the scalability issue. The paper des...