How does yEd convert Undirected graph to directed graph?

Question

I am wondering about the process of how yEd treats the undirected input graph as directed.

Undirected Graph; a--b, b--c, c--d, a--d, d--c

If an undirected .gml  file is opened in yEd, after doing the layout, it saved as a directed graph ( directed 1).  

Do yEd use any types of conversion algorithm for it?

Thank you very much.

Answer 1

Well, yEd always reads edges as directed. I.e. even in a GML file marked as "undirected", yEd will treat an (undirected) edge declaration of a--b as a directed edge from a to b.