Ki,P and Ki,T represent the cost of evaluating the i'th sub-policy P i of composite policy P Comp in case P Comp is evaluated provider-side or tenant-side respectively.
However, we deliberatly limit the granularity to sub-policies in the policy tree.
For now, we assume all sub-policies and expressions to be evaluated sequentially.
(3) Various ETS sub-policies should be carefully designed to balance economic growth and carbon mitigation.
The policy combination algorithm combines the effects of the sub-policies into the effect of the composed policy.
These policies are broken down into a number of sub-policies, with coverage offered for a specific set of risks.
They therefore consist of a target, a policy combination algorithm and an ordered list of sub-policies.
For composed policies, the sub-policies are evaluated in the given order; as a consequence, the policy tree is evaluated depth-first.
If the policy does apply, its condition is evaluated (in case of an atomic policy) or its sub-policies are evaluated (in case of a composed policy) and the result is returned.
Of these transformations, T1, T2, T3 and T4 allow policies to be split in an equivalent set of smaller policies; T5, T6 and T7 allow sub-policies of combined policies to be combined; T8 and T9 show the commutativity of PermitOverrides and DenyOverrides.
In case of FirstApplicable, only consecutive remote policy references in the sub-policies can be combined; in case of PermitOverrides or DenyOverrides, all remote policy references can be combined since these algorithms are commutative as shown by transformations T8 and T9 of Equations (T8 T9).
