"In system operations the term rollback is often used to imply that arbitrary changes can be reversed i.e. ‘rolled back’ from an erroneous state to a previously known acceptable state. We show that this assumption is flawed and discuss error-correction schemes based on absolute rather than relative change."

"By formulating this problem algebraically, the discussion is distanced from the sometimes emotional standpoints that bind system administrators to the notion of rollback: desperately wanting does not make it possible. The discussion about totalisation of fields is particularly useful, as it maps nicely to the flaws in this thinking. To deal with the inverse of a many-to-one map, one must invoke a policy or arbitrary selection."