This is a country of the future. The Knowheyana civilization is a very advanced one and its inhabitants are observed to be very intelligent. One of its peculiarities is that they always speak with negative phrases which are sometimes a puzzle.
Their country is small but very populated, that's why they live in apartment buildings. Six inhabitants (or families) occupy a six-story building. Then a guide explains to some tourists:
- A does not live above floor 3
- Neither C nor D live above either D or F
- F does not live under A or B, but does not live on top of D
- E does not live either above A or below B
Would you know what floor each one lives on?
Considering the second negation 4, E lives above B and below A. By negation 1 A does not live on the third floor. Then B, E and A occupy the first, second and third floor respectively. And for denials 2 and 3, C occupies the 4th floor, F the fifth and D the sixth.