title: How to prove a prob is np complete and is in np?
body: <p>Given a department needs a committee to select the department’s head. The committee cannot include people who have conflicts of interest with each other. The input consists of:</p>
  
  <ul>
  <li>the desired committee size</li>
  <li>a list of all people</li>
  <li>a list of all pairs of people that are conflicted. </li>
  </ul>
  
  <p>The goal is to determine whether there’s a conflict-free committee of that size.</p>
  
  <p>How can I show that this problem is NP-complete and is in NP?</p>