You have a 4×5 chess board as follows:

You can move the four bishops in any order (not necessarily alternating black and white), provided that no move puts a piece in danger of being captured by a bishop of the opposite color.

What is the fewest number of moves needed for the black and white bishops to exchange places?

The required fewest number of moves seem to be 18. 

Posted by K Sengupta on 2007-06-28 13:07:36