Interesting approach. I have another potential algorithm; see below.

Thanks :) As you may be able to tell, I've only been playing with the BGL on and off for a couple of days.

...

3) Can I colour the vertices before the algorithm does, thus fooling it into skipping the vertex's children?

It's a dirty trick, but you can do that :)

All's fair in love and programming ;)

So, the easiest solution is I think to use the filtered_graph<> adaptor

Ah ha! I'd completely failed to notice that in the docs! It really does sound just the job. Thanks for pointing that out. -John Donovan - He who really should read the docs more carefully. The content of this message and any attached file are confidential and/or privileged and are for the intended recipient only. If you are not the intended recipient, any unauthorised use, disclosure, copying, distribution or other dissemination is strictly prohibited. If you receive this message in error please notify the sender immediately by email, telephone or fax and then delete this email. Any attachment with this message should be checked for viruses before it is opened. Magenta Software Limited cannot be held responsible for any failure by the recipient to check for viruses before opening any attachment. Copyright in this email and attachments created by us belongs to Magenta Software Limited. Should you communicate with anyone at Magenta Software Limited by email you consent to us monitoring and reading any such correspondence.