In math/computers abstraction has a technical meaning that requires deterministic behavior for the abstraction to work. It isn't a proper abstraction if it does

In math/computers abstraction has a technical meaning that requires deterministic behavior for the abstraction to work. It isn't a proper abstraction if it doesn't always do the same thing underneath. Abstraction as a layering idea without regard to how it works is like the pop-pych version in that it is "right" but misses nuance.