  We prove several rigorous results about the asymptotic behaviour of the
numbers of polygons and self-avoiding walks confined to a square on the square
lattice. Specifically we prove that the dominant asymptotic behaviour of
polygons confined to an LxL square is identical to that of self-avoiding walks
that cross an LxL square from one corner vertex to the opposite corner vertex.
We also prove a result about the subdominant asymptotic behaviour of
self-avoiding walks crossing a square and extend this result to polygons
confined to a square. In addition, we investigate the problems of self-avoiding
walks and polygons in a hypercube in the d-dimensional hypercubic lattice.
