I. Introduction
Online interactions between stakeholders and engineers, e.g., on social media and product discussion forums, contain a variety of requirements-related information. Often, such information is unorganized and too noisy to be readily valuable for RE [3]. However, our observations [2] suggest that online discussions have a naturally emerging structure that can be leveraged to extract requirements-related information. A typical discussion starts with a problem description, which can be about a missing or a poorly-implemented feature of a target application. In response to the problem, other users may propose solutions, express support, or rebut the problem or solutions by pointing out unnecessary or unfeasible aspects. In addition to discussions in natural language, online forums include information such as votes and users' reputation.