(This question is closely related to What practical requirements are there for unity of an invention with multiple independent claims?, in which I ask for details about the "unity" of an invention when I can break down the invention into several independent claims.)
Let's assume there is a patent on a machine that "dries hair with hot air", and I have five other ideas how to dry hair (ice cubes, friction, whatever). I would like to avoid having to file five patents.
Obviously, I cannot claim a machine that "dries hair" any more.
When restricting myself to one independent claim (e.g., at the EPO), I would like to have a claim about a machine that "dries hair by other means than hot air"? Is that possible at all?