@LowBjorn how did you declare/construct the set s_Edges ? Is it related to the set of nodes s_Nodes or, the tuples (A, … are read in from an external source ? 

@mohansx I just realised that the formulation of my question was a little off compared to my aimms structure. In fact, the edges are defined through a binary parameter that indicates if an edge exists from node1 to node2. e.g. p01_EdgeExists(node1, node2) := 1; indicates that there is an edge.

I updated my post.

I have found a recursive solution allong the following lines:

• Define s_Children(i_node) to contain all direct descendants
• Define s_ChildrenAux(i_node) to contain all direct descendants of each node in s_Children(i_node), minus the nodes already contained in s_Children(i_node)
• Add s_ChildrenAux(i_node) to the set s_Children(i_node) and clear the auxiliary set.
• Repeat until no elements exist in the auxiliary set after generation.

It works, and is quick enough. If there’s an answer without a loop I would still be very interested.

@LowBjorn glad you were able to figure it out. This is a graph traversal problem, so I think you will need some kind of loop to find all the children. I will try to spend some time and see if we can improve on your approach.