AN EPISCOPAL VISITATION.
(
The Guarded Chessboard)
The white squares on the chessboard represent the parishes of a diocese.
Place the bishop on any square you like, and so contrive that (using the
ordinary bishop's move of chess) he shall visit every one of his
parishes in the fewest possible moves. Of course, all the parishes
passed through on any move are regarded as "visited." You can visit any
squares more than once, but you are not allowed to move twice between
the same two adjoining squares. What are the fewest possible moves? The
bishop need not end his visitation at the parish from which he first set
out.
Answer:
In the diagram I show how the bishop may be made to visit every one of
his white parishes in seventeen moves. It is obvious that we must start
from one corner square and end at the one that is diagonally opposite to
it. The puzzle cannot be solved in fewer than seventeen moves.
