The dominant species in Planet Blancneldos is the chamsonels. There are two types of chamsonels - logicians and philosophers. The chamsonels also have two different skin colors related to their veracity. Pink logician chamsonels always lie while blue logician chamsonels always tell the truth. Pink philosopher chamsonels always speak truthfully but blue philosopher chamsonels always speak falsely.

Here are the statements made by a married Chamsonel couple Pontus and Hemera to a friend from a neighboring planet who is color blind. The visitor however knows that either both of them are logicians or both of them are philosophers.

Hemera: My husband is a logician.
Pontus: My wife is a philosopher.
Hemera: Precisely one of us is blue and the other is not.

What are the types of Pontus and Hemera?

We're told they're both the same type.  From their first two statements it's clear that one of them is telling the truth and the other is lying.  Thus they are different colors.

This makes Hemera's second statement true, and from this it follows that Hemera is a blue Logician while Pontus is a pink Logician.

Posted by tomarken on 2014-05-01 11:00:03