Take a step back to move forward

You probably know the little riddle about the dog, the carrot and the rabbit that need to be transported to the other side of the river. The problem is that their owner can take only one of them on each trip across the river (it was a very big carrot! :-) )
When the dog and rabbit are left unattended, the dog devours the rabbit. And when the carrot and the rabbit are left unattended, the rabbit eats the carrot.

How can the rabbit, the dog and the carrot be transferred safely to the bank on the other side of the river?

If you haven’t heard this one, take a few moments to try solving it before you read on.
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The solution is to take the rabbit on the first trip, go back and take the carrot. Then take the rabbit BACK to the original bank, leave it there and take the dog. On the last trip, the rabbit is taken to the other bank and the owner can continue his journey with all three.

People find it difficult to solve this problem because of the fact that the solution involves giving up on something already achieved (the fact that the rabbit is already in the desired location). To solve this problem we need to perform an activity that seems to be counter-productive, i.e. bring the rabbit back to the starting point.

There are many situations in games and in life that require sacrificing what seems to us to be our most important asset. The most brilliant moves in chess are those that a player wins by letting his opponent take his or her queen.

There’s had been a famous soccer team in Israel that hadn’t done very well for a few years although they had the best players in the league. This was costing the owner of the team a lot of money.

Coaches were frequently replaced, but nothing helped until a new coach decided to remove the team’s star from a match  - the best and most expensive player.

The team won! Furthermore, it was their best game of the season. In the following matches the coach did the same thing, and the team won all their matches and had a good chance of winning the championship.

Sometimes what seems to be the most important asset is actually an obstacle. SIT recognizes this and offers the Subtrraction tool in which a list of important objects or system features is made and then removed one by one to see what happens.

In many cases there are surprising results!

1 Response to “Take a step back to move forward”


  1. 1 Michel LECOQ

    Dear Roni,
    As I told you a long time ago I often discussed with late E.W. Dijkstra.

    About the problem of (rabbit, dog, carrot) pleas watch following lecture from Dijkstra. It is failrly long but it will show you how he simplifies the problem and find a symmetric solution to a symmetric problem.
    The other problems ofthe lecture are also very interrestind from an ASIT point of view

    http://userweb.cs.utexas.edu/users/EWD/videos/EWD4.mpg

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