In front of Honza sat three veiled princesses, one of whom was Goldilocks. Honza's task was to find out which one she was.

The princess in the first chair said: "Goldilocks is not sitting in the third chair."

The princess in the second chair said: "I am not Goldilocks."

The princess in the third chair said: "I am Goldilocks."

The magical fairy revealed to Honza how many princesses were lying. Only with this advice was Honza able to identify the real Goldilocks.

Which of the princesses was Goldilocks?

(M. Volfová)
We can distinguish three cases depending on where Blondie could have been sitting:

1. If Blondie was sitting in the first chair, then

- the princess in the first chair would be telling the truth,
- the princess in the second chair would be telling the truth,
- the princess in the third chair would be lying.

2. If Blondie was sitting in the second chair, then

- the princess in the first chair would be telling the truth,
- the princess in the second chair would be lying,
- the princess in the third chair would be lying.

3. If Blondie was sitting in the third chair, then

- the princess in the first chair would be lying,
- the princess in the second chair would be telling the truth,
- the princess in the third chair would be telling the truth.

In the first and third cases, one princess would be lying, while in the second case, two princesses would be lying. Since the mouse council helped Honza identify Blondie, the mouse must have revealed that two princesses were lying. This corresponds to the second case, which means that Blondie was sitting in the second chair. (If the mouse had claimed that one princess was lying, Honza would not have been able to decide between the first and third cases.)

Suggested grading. 4 points for analyzing all cases; 2 points for determining the only possible case and placing Blondie.

Note. The previous analysis of possibilities can also be approached in reverse, i.e., based on the truth or falsity of individual statements, deduce where Blondie should be sitting. This would require discussing a total of eight cases:

- The statements of the princesses in the first and third chairs are contradictory, so these two princesses cannot both be telling the truth at the same time - this eliminates two cases.
- For the same reason, the princesses in the first and third chairs cannot both be lying at the same time - this eliminates another two cases.
- It is not possible for the princess in the second chair to be lying and the princess in the third chair to be telling the truth at the same time (that would mean there are two Blondies) - this eliminates another case.

The remaining three cases correspond precisely to the cases in the given solution.