title: Greedy algorithms and optimal substructure
body: <p>On <a href="http://en.wikipedia.org/wiki/Greedy_algorithm" rel="noreferrer">Wikipedia page</a> it is said that greedy algorithms are ideal only for problems which have optimal substructure.</p>
  
  <p><strong>Questions:</strong></p>
  
  <ol>
  <li>What is optimal/non-optimal substructure?</li>
  <li>What is local and global optimum?</li>
  <li>How to prove that Greedy algorithm yields global optimum?</li>
  </ol>