On the stability of some preservers

We study some “almost preserver” problems on von Neumann algebra modules. More precisely, we study (1) maps which “almost preserve” the right or left annihilator; (2) the “almost band preservers” – that is, maps which “almost preserve corners”, and (3) “almost centralizers,” which almost preserve module actions. Under certain conditions, we show that maps of these types are automatically continuous, and can be approximated by maps which precisely preserve these relations; often, the operators from the latter class are multiplication operators.