Answer
Inverse action: unscrew the bulb.
Work Step by Step
In loose terms,
let f( unscrewed bulb )= screwed bulb
We want the inverse to be defined on screwed bulbs
g( screwed bulb )= unscrewed bulb
So,
g(f ( unscrewed bulb )= unscrewed bulb
and
f(g( screwed bulb )= screwed bulb
[ f(g(x))=x and g(f(x))=x ]
Inverse action: unscrew the bulb