The logic representation proposed above is not strong enough to
determine what activity should be performed next. An expression such
The logic itself contain operators to represent that d and c must start imediatelly after b ends. This can be expresses as . But this representation does not allow for the flexibility that the expression 19 allow: dand c can start at different times, there can be any (consistent) activity performed between the end of b and the start of d or c, and so on.
In order to figure out from the formulas that express the procedures, constraints and policies, which activities are enabled, without changing the formulas, one need to define a new, stronger logic. That logic is defined below.