Solving Logical Puzzles

One Hundred Prisoners & a Lightbulb. Solving Logical Puzzles.

6:00am - 7:00am / Wednesday 26th July 2017 / Venue: Leggate Theatre Victoria Gallery & Museum
Type: Lecture / Category: Research
  • 54297
  • Admission: The event is FREE but please book a place at the following: https://www.eventbrite.co.uk/e/one-hundred-prisoners-and-a-light-bulb-solving-logical-puzzles-tickets-35630793663
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"A group of 100 prisoners, all together in the prison dining area, are told that they will be all put in isolation cells and then will be interrogated one by one in a room containing a light with an on/off switch. The prisoners may communicate with one another by toggling the light-switch (and that is the only way in which they can communicate). The light is initially switched off. There is no fixed order of interrogation, or interval between interrogations, and the same prisoner will be interrogated again at any stage. When interrogated, a prisoner can either do nothing, or toggle the light-switch, or announce that all prisoners have been interrogated. If that announcement is true, the prisoners will (all) be set free, but if it is false, they will all be executed. While still in the dining room, and before the prisoners go to their isolation cells (forever), can the prisoners agree on a protocol that will set them free?"

We will present a solution, however his public lecture will mainly address such puzzles of knowledge in general and their historical roots. One such root is a 19th century German translation of a French novella by Rabelais. There are many other riddles, such as the Muddy Children Puzzle (also known as the Wisemen Puzzle), the Surprise Examination, and Monty Hall. They often involve a (seemingly) paradoxical aspect making agents knowledgeable by announcements of their ignorance. More information on such puzzles is found on http://personal.us.es/hvd/lightbulb.html. This also refers to our puzzlebook entitled 'One Hundred Prisoners and a Light Bulb' (currently available in four languages, including English). There is a relation with the area in logic known as dynamic epistemic logic.

Hans van Ditmarsch is living proof that mobility does not harm a successful academic career. He works in Nancy, France. Barteld Kooi is living proof that mobility is not necessary for a successful academic career. He works in Groningen, the Netherlands.