Let
be a separable Hilbert space. We consider the Hilbert Grassmannian
consisting of
closed subspaces having infinite dimension and codimension and show that every bijective
transformation of
preserving the class of base subsets is induced by an element of
or it is the composition of the transformation induced by an element of
and
the bijection sending a subspace to its orthogonal complement.
Keywords
Hilbert Grassmannian, base subset, infinite-dimensional
topological projective space