RE: Editorial issues

> Should the first sentence read " ... a policy alternative with zero policy assertions"?

Yes, we think so too. We suggest that a CR issue be raised for this change.

>Conversely, it seems odd that <Policy/> should denote an
>alternative not a policy.  Intuitively, an empty <Policy/> seems
>like it should denote either a policy with no alternatives,
>or perhaps a policy with a single empty alternative.

<Policy/> is a policy with a single empty policy alternative. Why? The Policy operator is equivalent to the All operator. A collection of assertions in an All operator is equivalent to a policy alternative. In this specific case, it is an empty alternative. That is, a policy with a single empty policy alternative.

> However, this seems counter-intuitive in the context of intersection, and "all of the assertions in both alternatives"

It is neither set union nor set intersection. It literally means all of the assertions in both alternatives.

We hope this helps.

Regards,

Asir S Vedamuthu
Microsoft Corporation


From: public-ws-policy-request@w3.org [mailto:public-ws-policy-request@w3.org] On Behalf Of David Hull
Sent: Monday, April 30, 2007 10:42 PM
To: public-ws-policy@w3.org
Subject: Editorial issues

The rule for "Empty" states
<wsp:All /> expresses a policy with zero policy assertions. Note that since wsp:Policy is equivalent to wsp:All, <wsp:Policy /> is therefore equivalent to <wsp:All />, i.e., a policy alternative with zero assertions.
Elsewhere it says that <All/> represents alternatives, not policies, and there is certainly a distinction between an empty policy and an empty alternative.  Should the first sentence read " ... a policy alternative with zero policy assertions"?

Conversely, it seems odd that <Policy/> should denote an alternative not a policy.  Intuitively, an empty <Policy/> seems like it should denote either a policy with no alternatives, or perhaps a policy with a single empty alternative.
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The section on intersection states
If two alternatives are compatible, their intersection is an alternative containing all of the assertions in both alternatives.
This sounds like set union to me (except that we're not necessarily talking about sets).  If I talk about "all the people in both the USA and Canada", I'm not talking about people on the border, I'm talking about the combined populations.  However, this seems counter-intuitive in the context of intersection, and "all of the assertions in both alternatives" could be parsed as meaning "all of the assertions which are both in one alternative and in the other", that is, the set intersection (except that we're not necessarily talking about sets).

It would be good to clarify exactly what is meant.