Re: sets of sets
From: paul c <toledobythesea_at_oohay.ac>
Date: Tue, 01 Aug 2006 19:07:36 GMT
Message-ID: <YDNzg.307245$IK3.12150_at_pd7tw1no>
>
> PMFJI. Shouldn't that be, "the set of x such that x is a member of all
> members of S"?
>
> It seems to me that any subset of S is still a set of sets.
> ...
Date: Tue, 01 Aug 2006 19:07:36 GMT
Message-ID: <YDNzg.307245$IK3.12150_at_pd7tw1no>
David Cressey wrote:
> "paul c" <toledobythesea_at_oohay.ac> wrote in message
> news:a66zg.277513$Mn5.253389_at_pd7tw3no...
>
>
>> Then he mentions what I call "INTERSECTION S" which seems to mean the >> set of x such that x is a member of all subsets of S", (text pasted >> below, I hope):
>
> PMFJI. Shouldn't that be, "the set of x such that x is a member of all
> members of S"?
>
> It seems to me that any subset of S is still a set of sets.
> ...
(In his definition, the author stipulated that S was a set of non-empty sets.) That may not matter in general - I'm not sure that the paper doesn't make D&D's "first great blunder" when towards the end it says that a relation is a class, but I wasn't trying to read it to find that out, really just to look at different kinds of projectionss and maybe find out what the fuss about cylinders in RT was all about!
p Received on Tue Aug 01 2006 - 21:07:36 CEST