This .NET class wraps the AcDbObjectIdGraph ObjectARX class. 

ObjectIdGraph is derived from Graph and is used to represent the relationship of object IDs to one another. This class is used by the one pass purge method (Database.Purge(ObjectIdGraph idGraph)) to represent the references from one object ID to another. 

Autodesk.AutoCAD.DatabaseServices.Graph
    Autodesk.AutoCAD.DatabaseServices.ObjectIdGraph

Public sealed Class ObjectIdGraph
Inherits Graph

public sealed class ObjectIdGraph : Graph;