Title:  Projecting points between convex sets
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Abstract: Let X  and Y be two closed subspaces of a Hilbert space.
If we send a point back and forth between them by orthogonal projection,
the iterates converge to the projection of the point onto the intersection of
X and  Y.
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We will investigate when a sequence of orthoprojections
of a point in a Hilbert space on a finite family of closed
subspaces, or more generally, closed convex subsets, converges.