Hierarchy/Talk

This sentence... Every member is reachable from any other by following the relationship in either direction, but there is no way of coming back to a particular member by always following the relationship in the same direction. makes no sense at all to me. Does this mean that "any category node can be reached from any other category node"?

If so, then this is simply wrong - that's a property of a heterarchy or a neural network. A hierarchy is defined by each descendent having a single parent node (only!) and one or more descendents (or zero descendents at the leaf node level). Any organisational structure where descendent nodes can have more than one parent is not a hierarchy, by simple definition. The wikipedia is definitely not hierarchical in its informational content, otherwise we would not have so many debates about subpages and categorisation. - MMGB