🚀 go-pugleaf

In article <NICHAEL.93Jan5134917@kariba.bbn.com> ncramer@bbn.com writes:
>robertw@informix.com (Robert Weinberg) writes:
>
>   Manhole covers are manufactured in circular shape, rather than oval or square, to  
>   satisfy one paramount condition.
>
>   What is the condition ...
>
>The cover can't fall down the hole.
>
>   ... and why does a circular shape satisfy it?
>
>Because: DIAMETER_HOLE <= DIAMETER_COVER
>for all possible values of DIAMETER_HOLE and DIAMETER_COVER.
>
>   What other shapes would also satisfy the condition?
>
>Given the above, for any fully convex shape, I don't _think_ there are
>any others.
>
>Probably if I was clever enough (and/or had more time) perhaps I could
>come up with some more complicated shape.
>
>(Implicit in the above is the assumption that what's really keeping
>the lid from dropping is a narrow lip around the edge of the hole.  If
>we could play with the width of the lip, we could surely get other
>allowable shapes, but the problem would quickly become uninteresting.)

  Triangle shape also meets the condition.

-ping