title: How can I use Natural Language Processing to check if a paragraph contains predefined topics?
body: <p>We have a system that allows users to answer a question as free text and we want to check whether their answer contains any of our predefined topics. These topics will be defined prior to answers being submitted.</p>
  
  <p>We tried to use a method similar to spam detection, but this is only good for determining whether something is true/false, incorrect/correct. We need the response to say which of the predefined topics a piece of text contains. Is there an algorithm that would solve this problem?</p>