Hey everybody!

I am no maths student, I am studying business administration and for logistics we have an exercise which i can't even begin with so i would appreciate any help. I have to say that the professor never even told us about this problem but somehow we have to figure this out on or own. Thanks in advance!

We have a network 8x8 of a big chessboard. The 81 grid points are the crossroads. The crossroads are linked with the neighboring crossroads through edges of 1 m length horizontally and vertically. The horizontal streets can be crossed in both directions. The vertical 1st, 3rd, 5th, 7th and 9th streets from up to down and the 2nd, 4th, 6th, 8th from down to up. In this described graph can only the four fields in the centre of the chessboard turn clockwise to 90 degrees including the street orientation. The minimum number of visited edges of the optimal solution of this graph's chinese postman problem's is then:

22

23

24