On 8/22/06, Charlie Reams <calr3(a)cam.ac.uk>
wrote:
Can someone point me to one of these cycles? I
don't remember seeing
one, although I've no doubt they exist. I just can't imagine a situation
in which much is gained by allowing it and, given that certain features
would be a lot easier if the system were guaranteed cycle-free, I think
we might be better off disallowing them. But I'd like to see a few of
them "in the wild" before making my mind up.
They're obviously not easy to find since we have no built in features
to do that, and every time one becomes known, it gets fixed :) Maybe
Magnus's tool can help us out? I don't think we have any permanent,
accepted ones, if that's what you're asking...they just happen from
time to time when enough sufficiently dubious category links get
made...
Steve
The problem is different senses of 'subcategory': there's [1]
"the set
of objects in B are a strict subset of the set of objects in A", which
is loop-proof, and [2] 'B is a topic that is usually discussed in the
context of A'
For example:
London -[2]-> Thames Valley -[1]-> London, comes to mind
Russia -[2]-> Soviet Union -[1]-> Russia, as well.
Also, another entirely reasonable cycle would be:
Universe -[contains]-> Human beings -[who have]-> Human thought -[which
includes]-> Philosophy -[which studies the]-> Universe
See [[WordNet]] for a serious attempt to tease out the relationships
between concepts in detail: there are _lots_ of possible ways that one
thing can be related to another.
-- Neil