Home > Logic
| Day-knights and night-knights 3 (Posted on 2011-03-21) |
 |
Day-knights tell the truth in the day and lie at night. Night-knights lie in the day and tell the truth at night.
A:B is a day-knight.
B:A is a night-knight, and it is night.
What are A and B, and is it day or night?
|
|
Submitted by Math Man
|
|
Rating: 1.0000 (1 votes)
|
|
|
Solution:
|
(Hide)
|
|
Suppose it is night. If A is a day-knight, then A is lying, so B is a night-knight. Then, B is telling the truth, so A is a night-knight. That is a contradiction. If A is a night-knight, then A is telling the truth, so B is really a day-knight. Then, B is lying, but A is a night-knight, and it is night. That is a paradox, so it is day. Therefore, B is lying, so B is a night-knight. That means that A is lying, so A is also a night-knight. Therefore, they are both night-knights, and it is day.
|
Comments: (
You must be logged in to post comments.)
| |
Subject |
Author |
Date |
 | Solution | Dej Mar | 2011-03-21 14:16:16 |
|
|
Please log in:
Forums (0)
Newest Problems
Random Problem
FAQ |
About This Site
Site Statistics
New Comments (3)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On
Chatterbox:
|
