Tuesday, August 11, 2015

Russian Railroad Puzzle

This was a fun and quick puzzle as the technique from Peter Norvig's solution to the Zebra Puzzle can be reused directly. It's very nice to be able to formulate the conditions in terms that are clear and almost like plain English.


Passengers in a Railroad Compartment 
Six passengers sharing a train compartment are from Moscow, Leningrad, Tula, Kiev, Kharkov, and Odessa.
  1. A and the man from Moscow are physicians 
  2. E and the Leningrader are teachers. 
  3. The man from Tula and C are engineers. 
  4. B and F are WWII veterans, but the man from Tula has never served in the armed forces. 
  5. The man from Kharkov is older than A. 
  6. The man from Odessa is older than C. 
  7. At Kiev, B and the man from Moscow got off. 
  8. At Vinnitsa, C and the man from Kharkov got off. 
Match initials, professions, and cities. Also, are the facts both sufficient and necessary to solve the problem? 
from Boris A Kordemksy, The Moscow Puzzles: 359 Mathematical Recreations, p111.