D connected nodes

[Gary]

Is it possible to be more precise about which nodes are included in the collection of D-connected (separated nodes)?

Although a Utility node can not be part of the soft/hard node list it appears that they are included in the list of Connected or Separated nodes produced by the API calls. Are these nodes treated as Chance nodes without evidence? Can a utility be considered as a source node? What is the corresponding situation for decision nodes? Does their status depend on whether the arrow enters or leaves? (i.e time order?).

Is the source node always included in the D-connected list?

I have not been able to get the d-separation analysis tool to work from the GUI for influence diagrams to check these conditions visually?

Thanks

Gary

[Frank Jensen]

The precise effects of the API functions for computing d-connected and d-separated nodes are given in the Hugin API Reference Manual, Section 8.4:

In influence diagrams, links pointing at decision nodes (also known as information links) will be ignored for the purposes of performing d-separation analysis. Moreover, the hard and soft lists must not contain any utility nodes.

A utility node is just like any other node, except that it cannot have evidence (and hence cannot be a source node).

A source node is d-connected to itself unless it has hard evidence.

The Hugin GUI currently disables d-separation analysis for influence diagrams.

[The treatment of networks with decisions could change in the future.]