Multi-Parent linking

Question

Where I can find the display algorithm for multi-parents linking. I like to draw it on 2-dimension paper without crossing lines.

So it is connecting with Set of parents to set of children where there is many to many relationship.

Answer 1

The layout engines in graphviz attempt to solve this problem in various ways, though I think they will all allow lines to cross if the diagram is complex enough.

The theory page has some links that may be of interest.

Answer 2

You might want to read this and this before looking further. Planarity is a tricky animal and in many real world applications is simply not doable.