Re: [poe] Note on Policy Inference

> I think the use case a processor is facing is: a specific user wants to taken an action on a specific asset, this needs to be evaluated. First the processor must find out if a partOf relationship is set between the specific user and the assignee W3C and if the specific asset has a partOf relationship with the target Dataset1. Such partOf relationships will be set in many cases outside a policy and this may cause practical problems.

what practical problems? if there's no indication about any partOf/memberOf/.. relation, then you simply can't compute any inferences.

For example:
```turtle
# :Alice requests the permission to odrl:play asset :PartA:
<http://example.com/request:01>
    a odrl:Request;
    odrl:permission [
        a odrl:Permission ;
        odrl:target :PartA ;
        odrl:action odrl:play ;        
        odrl:assignee :Alice
    ] .

# :Alice is permitted to odrl:present :Dataset1
<http://example.com/policy:01>
    a odrl:Policy;
    odrl:permission [
        a odrl:Permission ;
        odrl:target :Dataset1 ;
        odrl:action odrl:present;        
        odrl:assignee :Alice
    ] .
```
one way to evaluate such a request is to:  
+ merge it with existing policies and check whether any conflicts arise; if that's the case -> **deny**
+ for each policy, check whether the set of (atomic) rules of the request is a subset of the set of (atomic) rules of the policy ![\forall p \in P : R_{request} \subseteq R_p](https://latex.codecogs.com/gif.latex?\forall&space;p&space;\in&space;P&space;:&space;R_{request}&space;\subseteq&space;R_p); if that's the case -> **grant**
+ otherwise ->  **unknown**

So if we don't know that `odrl:play` is actually a narrower term for `odrl:present` and that `:PartA` is actually a part of `:Dataset1`, the response to Alice's request would simply be **unknown** (or any other default).



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Received on Monday, 26 June 2017 05:49:02 UTC