The hardest logic puzzle ever becomes even tougher
  "The hardest logic puzzle ever" presented by George Boolos became a target for philosophers and logicians who tried to modify it and make it even tougher. I propose further modification of the original puzzle where part of the available information is eliminated but the solution is still possible. The solution also gives interesting ideas on logic behind discovery of unknown language. 
Nikolay Novozhilov
math.LO cs.AI