Let H and K be complex complete indefinite inner product spaces, and ℬ(H,K) (ℬ(H) if K = H) the set of all bounded linear operators from H into K. For every T ∈ ℬ(H,K), denote by the indefinite conjugate of T. Suppose that Φ: ℬ(H) → ℬ(K) is a bijective linear map. We prove that Φ satisfies for all A, B ∈ ℬ(H) with if and only if there exist a nonzero real number c and a generalized indefinite unitary operator U ∈ ℬ(H,K) such that for all A ∈ ℬ(H).
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-sm174-2-5, author = {Jianlian Cui and Jinchuan Hou}, title = {Linear maps preserving elements annihilated by the polynomial $XY-YX^{\dag }$ }, journal = {Studia Mathematica}, volume = {173}, year = {2006}, pages = {183-199}, zbl = {1091.47030}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm174-2-5} }
Jianlian Cui; Jinchuan Hou. Linear maps preserving elements annihilated by the polynomial $XY-YX^{†}$ . Studia Mathematica, Tome 173 (2006) pp. 183-199. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm174-2-5/