A manifold is something that can't be a function because it is multi-valued
where a function must be single-valued.

A circle, the set of points which satisfy the equation x^2 + y^2 = r^2, is a
manifold of points because there are two values of y that satisfy the
equation for each value of x, -r < x < r.  If we restricted ourselves to y
>= 0 (or to y <= 0) then we would get a set of points which is a function of
x.

-- rec --

On Tue, Aug 4, 2009 at 11:12 AM, Nicholas Thompson <
nickthomp...@earthlink.net> wrote:

>  I wonder if anybody has any comment to make on the following passage from
> EB holt? (Remember, I am the guy who tends to ask questions of PEOPLE when
> he should look them up, so feel free to ignore me here.)
>
> Holt (1914) writes:  "If one is walking in the woods, and remarks that "All
> this is Epping Forest," one may mean that this entire manifold of some
> square miles is the forest; or else, that every twig and leaf which one
> sees, in short, every least fragment of the whole is Epping Forest.  The
> former meaning is the true one; the latter meaning is absolutely false.
> Everyone admits that while a circle is a manifold of points, a single point
> is not a circle; while a house is a manifold of bricks, boards and nails and
> any single brick is not a house. "
>
> I am interested in this concept of "manifold" .  Can anybody make the
> metaphor come alive for me?   Is it like a shroud?
>
> Nick
>
>
> Nicholas S. Thompson
> Emeritus Professor of Psychology and Ethology,
> Clark University (nthomp...@clarku.edu)
> http://home.earthlink.net/~nickthompson/naturaldesigns/<http://home.earthlink.net/%7Enickthompson/naturaldesigns/>
>
>
>
>
>
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