This is an informal lecture to celebrate the unprecedented
 event that I understand some piece of the work of some economists.
 Roth and Shapley have won the "The Sveriges Riksbank Prize in Economic
 Sciences" (aka nobel prize in Economics) for their work on 'stable
 allocations and market design'. It is also a thriving subject in
 mathematics. I will start with the original Gale-Shapley problem:
  10 men and 10 women are to be married to each other so that there are no
 divorces. Is it possible?
 Then we proceed to the question of 'how to allocate patients to
 hospitals' or 'children to schools'. In the end I shall talk about
 another allocation problem motivated by the above. The entire talk will be
 very elementary and understandable to undergraduates.