Finding edges of a given polyhedra in 3D

Hello,

I have a problem to solve.

How can I find the edges of a polyhedra in 3D having only coordinates
of its vertices?
All the pairs of the vertices constitute corresponding line segments.
Some of them are diagonals and some of them are edges. I have to
distinguish them based only on the vertices data.

I searched a little and found no solution. I intended only very heavy
algorithm in 2D which consist on finding which of the line segments
intercept with each other in the area of the polyhedra (based on this I
could decide which is diagonal which is edge). This doesn't work of
course in 3D.

regards

.