Brain-Twisters II

The puzzles in this page will generally be examples of the categories I enjoy most - those involving geometry, topology, probability, and truth paradoxes. Presenting them will often involve the use of tables and figures. The page should still be readable with text-based browsers such as Lynx, provided the reader has some way of downloading and viewing the gif figures.

Puzzle #1

Brought back by popular demand, this is yet another set of the classic "Lady or the Tiger" puzzles. The rules this time are a little different. If a lady is in Room I, then the sign on the door is true, but if a tiger is in it, the sign is false. In Room II, the situation is the opposite: a lady in the room means the sign on the door is false, and a tiger in the room means the sign is true. Again, it is possible that both rooms contain ladies or both rooms contain tigers, or that one room contains a lady and the other a tiger. The signs on the doors of the rooms are as follows:

I

BOTH ROOMS CONTAIN LADIES

 II

BOTH ROOMS CONTAIN LADIES

Which door should you open (assuming, of course, that you prefer the lady to the tiger)?

Solution.

Puzzle #2

This time the signs read as follows:

I

AT LEAST ONE ROOM CONTAINS A LADY

 II

THE OTHER ROOM CONTAINS A LADY

What should you do?

Solution.

Puzzle #3

The signs now read:

I

IT MAKES NO DIFFERENCE WHICH ROOM YOU PICK

 II

THERE IS A LADY IN THE OTHER ROOM

What should you do?

Solution.

Puzzle #4

Here are the signs:

I

IT DOES MAKE A DIFFERENCE WHICH ROOM YOU PICK

 II

YOU ARE BETTER OFF CHOOSING THE OTHER ROOM

What should you do?

Solution.

Puzzle #5

This time the signs are not attached to the doors:

THIS ROOM CONTAINS A TIGER

 BOTH ROOMS CONTAIN TIGERS

Can you still figure out the solution?

Solution.

Visit:

Puzzles 1-5 adapted from Smullyan, R. (1982) The Lady or the Tiger? and Other Logic Puzzles, Knopf.
Revised: August 29, 1996