Responding to part of my own query...
(2) The remove_edge_if() and clear_vertex() functions have comments stating that they are wrong. Are the functions wrong or are the comments wrong? If the functions are wrong, is there a plan to fix them? (3) The remove_vertex() function states that it is "under construction". Who is doing the construction? Is there a time-frame for this?
I now see the problem with implementing clear_vertex() and remove_vertex() for subgraphs. In order for these two functions to have the same meaning for subgraphs that they have for regular graphs, they would have to operate on the set of all subgraphs -- not just induced subgraphs. This is because, in general, clear_vertex() will cause a subgraph to become non-induced and the context for calling remove_vertex() will usually make sense if the subgraph is non-induced. What we really need is at atomic operation that is "clear_vertex() followed by remove_vertex()". This makes me wonder why the remove_vertex() function does not do this for graphs in general. Any insight into this would be helpful. David