Iconic American mathematician, logician and puzzle-maker Raymond Smullyan has died at the age of 97.
News of his death was announced by his step-niece Alison Fleming, who said: "Uncle Raymond Smullyan died yesterday at 97 years of age. He was a brilliant logician (What is the Name of this Book?), mathematician, musician, and magician and challenged one's intellect in all his domains."
Smullyan was born in New York and showed an aptitude for maths and music from a young age. While his musical talents were catered to, his interest in science was not. As the school he was attending did not offer the maths courses he wanted, he left to study alone.
He went on to attend several different colleges, gaining his PhD from Princeton University in 1959. As well as studying maths and composing chess problems and puzzles, he also learned how to do magic tricks – becoming an accomplished magician.
Over his career, he wrote numerous research articles on mathematical logic, set theory and Eastern philosophy, while also publishing famous logic puzzles such as 'Lady or Tiger':
A problem from in Raymond Smullyan's The Lady or the Tiger?
A certain king likes to entertain himself by making his prisoners play a game to decide their fate. The prisoners are presented with two doors. In a room behind each door is either a lady whom the prisoner may marry, or a tiger whom may eat the prisoner. A clue is written on each door and the prisoner decides which door to open based on these clues. The clues provided to three prisoners brought before the king are below. Try to figure out which door each prisoner should open.
Prisoner 1 is told that exactly one of the following clues is true and exactly one is false.
Door 1: There is a lady behind this door and a tiger behind the other.
Door 2: There is a lady behind one of the doors and a tiger behind the other.
Prisoner 2 is told that either both clues are true or both are false.
Door 1: Either there is a tiger behind this door or a lady behind the second door.
Door 2: There is a lady behind this door.
Prisoner 3 receives directions which are a bit trickier since the first two escaped. This prisoner is told that if a lady is behind door 1 then the clue on door 1 is true, but if a tiger is behind door 1 then the clue on that door is false. Door 2 follows the opposite rule: if a lady is behind door 2 the clue on door 2 is false, but if a tiger is behind door 2 the clue on that door is true.
Door 1: A lady is waiting behind at least one of the doors.
Door 2: A lady is waiting behind the other door.
Since his death was announced, a number of tributes have been made to Smullyan from fellow mathematicians and philosophers, as well as fans across the globe.