Differentiable reasoning over text

We all rely on search engines to navigate the massive amount of online information published every day. Modern search engines not only retrieve a list of pages relevant to a query but often try to directly answer our questions by analyzing the content of those pages. One area they currently struggle at, however, is multi-hop Question Answering that requires reasoning with information taken from multiple documents to arrive at the answer. For example, suppose that we want to find out What is the size of the COVID-19 virus?. Systems that try to answer this question first need to identify the virus responsible for COVID-19 (SARS-CoV-2) and then look for the size of that virus (50-200 nm).