SOC 2 Composition 1 slide-27

The Meaning of this

Recall that:
P^p, E^p represents the union of the properties of each set of conditions. For example,
P^p = ∪ Prop_i^j, C_j=(fluent^j,Prop_i^j) → C_j ∈ P.

If P^p(W_j) ∉ E^p(W_k) ,
then it is impossible for the effects of W_k
to affect the preconditions of W_j
since none of the properties of the former are even mentioned in the properties of latter.

This is a Safety conditon that is too strong,
it makes some compositions imposible.