Re: Is {{}} a valid construct?

Bob Badour wrote:
> David Marcus wrote:
>
> > Neo wrote:
> >
> >>>>>>Can an empty set contain an empty set?
> >>>
> >>>>>If a set contains an element, be it the empty set or not,
> >>>>>its not the empty set.
> >>>>>So put your one empty bag of potatoes into your other
> >>>>>empty bag of potatoes. And wush your second bag is not
> >>>>>empty anymore. You see, it contains the first empty bag.
> >>>
> >>>>Thanks, however I am still confused as Bod Badour in
> >>>>comp.database.theory has the following reply to your post:
> >>>
> >>>The two answers say the same thing.
> >>
> >>Do'h! time to untunnel my vision B(
> >>
> >>>Why are you confused?
> >>
> >>Prior to putting one bag inside the other, there were two empty bags
> >>meaning two empty sets. How could this be? Set theory says otherwise.
> >
> > Because a bag is a metaphor, not a set.
> >
> >
> >>My explanation is that a set is only defined by its elements and does
> >>not include the container (ie {} or bag). Thus if there aren't any
> >>elements, there is no set, not even an empty set. Only then can two
> >>separate empty bags be considered equivalent.
> >
> > Sets don't have "containers". The empty set is most certainly a set. You
> > can't argue by metaphor.
> >
> >
> >>Better yet, how would one create/select {{}} within a relational
> >>database or similar?
> >
> > What makes you think that a relational database provides a complete
> > model for ZFC?
>
> David,
>
> Just to alert you, Neo is one of the resident cranks on
> comp.databases.theory

Thanks.

> Neo's cross-posting c.d.t and sci.logic is rather trollish.
>
> {} would be the nullary relation called DUM having cardinality and
> degree zero
> {{}} would be the nullary relation called DEE having cardinality one and
> degree zero
>
> DEE and DUM are the relational analogs of true and false.
>
> Neo has been following c.d.t long enough that he should know that answer
> himself. It's not like it hasn't been explained to him scores of times.

Some people can't learn.

-- 
David Marcus