You are here

Can you Crack the Lying and Truth-telling Lion and Unicorn Puzzle

Can you Crack the Lying and Truth-telling Lion and Unicorn Puzzle

Lying and truth-telling lion and unicorn puzzle: both said, "Yesterday I was lying", What day is Today?

A girl meets a lion and a unicorn in a forest. The lion lies every Monday, Tuesday and Wednesday and speaks the truth the other days. The unicorn lies every Thursday, Friday and Saturday and the other days he speaks the truth. "Yesterday I was lying", the lion told the girl. "So was I", said the unicorn. What day is it?

Just the answer is not enough, you have to establish bullet-proof reasons leading to the solution.

Time to solve: 10 minutes.

Confusing? Start trying, but try with logic.

Solution to the lying and truth-telling lion and unicorn puzzle

Both lion and unicorn said on "Today" that they were lying "Yesterday".

First key pattern in the statements considering the lion and the unicorn individually:

Two consecutive days of lying or truth-telling could not have been "Yesterday" and "Today" for both. The simple logic table shows the situation clearly,

Consecutive days logic table

Explanation: Consider Lion: He said, "Yesterday I lied". If he tells the truth today, yesterday he must have been actually lying. And if he lies today, he must have telling the truth yesterday. Same is true for the unicorn.

Second conclusion considering both lion and unicorn:

One of them was lying and the other telling the truth today and also on Yesterday (look at the last two rows of the logic table).

Four days are eliminated:

The first key pattern and conclusion eliminates Tuesday, Wednesday, Friday and Saturday as the contender for "Today".

Third key pattern and conclusion:

Both lion and unicorn tells the truth on Sunday. By second conclusion then, Sunday cannot be either "Yesterday" or "Today".

Sunday and Monday are eliminated:

As Sunday cannot be "Yesterday", Monday cannot also be "Today".

The only candidate left for "Today" is Thursday.

Answer: Today is Thursday.

Let's verify from the second logic table: (this explains the answer clearly)

The lion and unicorn puzzle truth table

Advise: How to solve confusing logic puzzles

Focus on key pattern discovery and logic analysis. The right answer will follow quickly and automatically without going round in circles.

Puzzles you will enjoy

Easy to hard categorized brain teasers with systematic solutions from

Challenging brain teasers with solutions: Long list.

More lying and truth-telling riddles

Two doors with two guards - one lies, one tells the truth

Puzzle | Truth and Lie

Truth-Tellers and Liars