Graph Nodes:
X8;X1;X11;X9;X2;X12;X7;X3;X13;X6

Graph Edges:
1. X8 o-> X11
2. X8 o-> X12
3. X8 o-o X7
4. X1 o-o X9
5. X1 o-o X2
6. X1 o-o X3
7. X1 o-o X6
8. X7 o-> X11
9. X13 o-> X11
10. X9 o-> X12
11. X7 o-> X12
12. X7 o-o X3
