Hey Rick
Thanks for answering.
It should be easier with picture:
[ATTACH=CONFIG]34440[/ATTACH]
On that picture (SCHEMATICS1) there is 4 nodes wich are intersections between lignes and the white square.
These are the nodes i don't want to move when i run an algorithm.
When i say "the nodes move", it's like in this picture: [ATTACH=CONFIG]34441[/ATTACH]
Nodes and edges move all together.
For now, i can't use argis, but as you say, i will try to select them (only nodes) after running my algorithm and run the initial position algorithm.
I will tell you if it works.
Thanks