Re: universe of discourse

[bob@MEGALITH.RATTLESNAKE.COM]

   >  > What is a universe of discourse?
   >
   > That topic within which you and your interlocutor are talking.

To which a.rosta@uclan.ac.uk responded:

   This is how I understood it. So if you're in the garden and
   say "every flower is yellow", it might mean "every flower in
   the garden".

Yes.

   Going by what you say, a universe of discourse is then not the
   same thing a s a possible world (contra Lojbab).

A possible world may be a universe of discourse, or maybe not;
a universe of discourse may not be a possible world, it may be
an impossible world.

   Lojbab seemed to be saying that it is possible to construct
   a world containing only even numbers. This is what I cannot
   conceive of.  I can of course easily understand a discussion
   focused entirely on even numbers, where odd numbers are
   irrelevant, and where {ro namcu} might be intended to mean
   "all even numbers".

It may be that you and he are using the word `construct' in different
ways.  I interpret your phrase in the above paragraph, "... a
discussion focused entirely on even numbers..." as *constructing* such
a world, hence your saying words that would agree with Lojbab if you
interpreted what you say the way I do.

Certainly, also, at one time I understood my math textbook as telling
me how to _construct_ a universe of even numbers without there being
odd numbers at all.  (Every entity has a successor; the entities
interchange among themselves according to the following rules; that
sort of thing.  No, this is not the jargon that should be used; I have
forgot most of it.)  This latter process would fit your meaning of the
word `construct'.  The problem suffered by an ordinary human is to
forget knowledge about numbers that were learned years ago but don't
apply in the specific circumstances.  A mathematician will forget, so
as not to get confused (or at least give a good appearance of
forgetting, so as to create a memory for the student [`lo tadni'? `loi
tadni'?]).

--

    Robert J. Chassell               bob@rattlesnake.com
    P. O. Box 693                    bob@ai.mit.edu
    Stockbridge, MA 01262-0693 USA   (413) 298-4725