The missing piece of "just choose to always go left" is that this is a degenerate and uninteresting case. No decision is being made.
The range must be discrete and at least 2 possible values.
There is nothing about optimality at all here. Even if both possible outputs are equally "optimal", there is no procedure to pick one in a finite amount of time.
The range must be discrete and at least 2 possible values.
There is nothing about optimality at all here. Even if both possible outputs are equally "optimal", there is no procedure to pick one in a finite amount of time.