title: How to formulate LP for shortest path problems?
body: <p>I'm trying to understand how the LP formulation for shortest path problem works. However I'm having trouble understanding constraints. Why does this formulation work?</p>
  
  <p><a href="http://ie.bilkent.edu.tr/~ie400/Lecture8.pdf" rel="nofollow">http://ie.bilkent.edu.tr/~ie400/Lecture8.pdf</a></p>
  
  <p>I'm having trouble understanding how the constraints work at pages 15 and 17. I got the main idea and I understand how and why x should take some values but I did not understand how the whole system works in terms of math. Can someone explain? In the exam, I am supposed to be able to create and modify such constraints but I am pretty far from doing that.</p>