A word for inverted requirements
Solution 1:
I would say not, for two reasons:
- The requirement that something be unset is still a requirement
And
- It is possible to have a mixture of positive and negative requirements. That is (X & Y & !Z) to employ the notation you used. A familiar example would be X = engine running, Y = a gear engaged, Z = parking brake applied. If any one of the conditions (X), (Y) and (not Z) is untrue the car (with automatic transmission) won't go anywhere.