All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Logic
The Two Logicians (Posted on 2003-04-11) Difficulty: 3 of 5
Two logicians place cards on their foreheads so that what is written on the card is visible only to the other logician. Consecutive positive integers have been written on the cards. The following conversation ensues:

A: "I don't know my number."

B: "I don't know my number."

A: "I don't know my number."

B: "I don't know my number."

........ n statements of ignorance later..........

A or B: "I know my number."

What is on the card and how does the logician know it?

See The Solution Submitted by Ravi Raja    
Rating: 2.5556 (9 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution re: Attempt | Comment 3 of 7 |
(In reply to Attempt by DJ)

This seems rigth, but I think there is more. Each logician knows the others number then they wait for n to reach the other fellows number. Assume x is equal to the number on the other logiacians head. As soon as x-1=n or x=n, then automatically, the logician knows his own number. Since in any situation (I tested this) the logician with the higher number will always see the x-1 or x =n situation first, the logician with the higher number will win. It does not matter if the numbers are even or odd or that A went first.
  Posted by Jon on 2003-04-11 06:21:55

Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (1)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (24)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2024 by Animus Pactum Consulting. All rights reserved. Privacy Information