The heptagram / pentagram problem

This program deals with the heptagram problem. It uses this figure.

The problem is: fill in the numbers 1, 2, .. 14 in such a way, that the sum along all lines is constant. It is possible, according to my program there are 1008 different solutions, counting rotations and mirror solutions.

One might think that it should also be possible to fill in the numbers 1, 2, ..,10 in the pentagram shown above, such that the sum along the five lines are constant. According to my program, it is not possible. I did not understand why, it took me about nine months to figure out how to prove that no solutions exist. The proof will be published on sourceforge, but not right away, you should have the fun of proving it yourself. It turned out to be very elementary.

You can find my program at sourceforge follow instructions in the readme.txt file

Programs to follow will be a Mandelbroot/Julia program, a Feigenbaum program, and my favourite, a program on random walk. The two first are in place now, but the one on random walk is very far from completion.