Transformations on the set of all $n$-dimensional subspaces of a Hilbert space preserving orthogonality
Máté Győry · Publicationes Mathematicae Debrecen · 2004
In our paper we generalize Uhlhorn's version of Wigner's famous unitary-antiunitary theorem by describing the transformations preserving the orthogonality between higher dimensional subspaces under certain conditions.