On linear maps preserving generalized invertibility and related properties

Let H be an infinite-dimensional complex Hilbert space, B(H) be the algebra of all bounded linear operators on H. We study surjective linear maps on B(H) preserving generalized invertibility. We also investigate surjective linear maps preserving Fredholm (respectively, semi-Fredholm) operators. Our results improve those of Mbekhta, Rodman and Šemrl.