sawyl | One these things is not quite the same...

An interesting poser came my way today: given various sets of objects, some of which may be members of other sets, how many distinct collections of sets exist such that all objects are either in one collection or the other? After a bit of pondering and graphic, I discovered that in my case the answer appeared to be one. Which given that the whole exercise was intended to allow me to partition the objects up into groups that could safely be processed in parallel wasn't really the answer I wanted...