In article <d9127be5-e7f3-44c9-a7f4-5a3e9751d889 @e14g2000yqe.googlegroups.com>, tttpppggg@yahoo.com says... > > On Oct 15, 10:39 am, Arturo Magidin <magi...@member.ams.org> wrote: {...] > > A projection is a map that equals its square, T = T^2 (under > > composition). > > Sorry, but your description is not a match for any of > http://en.wikipedia.org/wiki/Projection_%28mathematics%29 [...]
From the page:
"In linear algebra, a linear transformation that remains unchanged if applied twice (p(u) = p(p(u))), in other words, an idempotent operator."
