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Re: FW: [Bug 4553] Exact meaning of "all of the assertions in both alternatives"

From: Christopher B Ferris <chrisfer@us.ibm.com>
Date: Tue, 22 May 2007 16:50:25 -0400
To: David Hull <dmh@tibco.com>
Cc: Asir Vedamuthu <asirveda@microsoft.com>, "public-ws-policy@w3.org" <public-ws-policy@w3.org>, public-ws-policy-request@w3.org
Message-ID: <OF04AD47D9.6911E6AA-ON852572E3.00715AA0-852572E3.0072591A@us.ibm.com>
How about:

If two alternatives are compatible, their intersection is an alternative 
containing 
all of the occurrances of all of the assertions in both alternatives 
(i.e., the bag 
union of the two).

Cheers,

Christopher Ferris
STSM, Software Group Standards Strategy
email: chrisfer@us.ibm.com
blog: http://www.ibm.com/developerworks/blogs/page/chrisferris
phone: +1 508 377 9295

public-ws-policy-request@w3.org wrote on 05/15/2007 11:35:11 PM:

> Asir Vedamuthu wrote: 
> * Bag union: [A B B B C C C C C D D] (all
> occurrences of all assertions from 1
> together with all occurrences of all assertions from 2)
> 
> 
> Your first interpretation is correct!
> 
> The phrase "all of the assertions" is neither set union nor set 
> intersection. It literally means all of the assertions in both 
alternatives.
> 
> If you think the phrase "all of the assertions" does not capture the
> intent, may I request you to propose a concrete wording?
> 
> This is where one gets into trouble using lesser-known structures 
> like bags.  It would be nice to say
> 
> "If two alternatives are compatible, their intersection is the bag 
> union of the two alternatives."
> 
> Unfortunately, "bag union" is not a widely-recognized term.  Another
> attempt would be to refer to policy expressions, since just 
> concatenating the contents of two (normalized) <All> expressions 
> will produce an expression for the bag union (which, I suspect, is 
> why "all of the assertions in both alternatives" may seem obvious). 
> Unfortunately, we're defining an operation on policies, not policy 
> expressions.  I suppose you could say
> 
> "If two alternatives are compatible, their intersection may be 
> represented by a policy expression formed by concatenating their 
> normalized expressions."
> 
> It's a mouthful, but it probably comes closest to capturing the 
> intuition behind the original statement.  Failing that, you could 
> bite the bullet and spell out bag union here:
> 
> "If two alternatives are compatible, their intersection is an 
> alternative in which the multiplicity of each assertion is the sum 
> of the multiplicities in the two alternatives."
> 
> or something equally unwieldy.
> 
> Finally, if you prefer to keep the original wording, at least gloss it:
> 
> "If two alternatives are compatible, their intersection is an 
> alternative containing all of the assertions in both alternatives 
> (i.e., the bag union of the two)."
> 
> That's probably close enough.  It also reinforces that you don't 
> mean just any alternative containing all of the assertions in both 
> alternatives, but one containing only those assertions.
> 
> Regards,
> 
> Asir S Vedamuthu
> Microsoft Corporation
> 
> 
> -----Original Message-----
> From: public-ws-policy-qa-request@w3.org [mailto:public-ws-policy-
> qa-request@w3.org] On Behalf Of bugzilla@wiggum.w3.org
> Sent: Friday, May 11, 2007 8:31 AM
> To: public-ws-policy-qa@w3.org
> Subject: [Bug 4553] Exact meaning of "all of the assertions in both 
> alternatives"
> 
> 
> http://www.w3.org/Bugs/Public/show_bug.cgi?id=4553
> 
>            Summary: Exact meaning of "all of the assertions in both
>                     alternatives"
>            Product: WS-Policy
>            Version: CR
>           Platform: All
>                URL: http://lists.w3.org/Archives/Public/public-ws-
>                     policy/2007May/0019.html
>         OS/Version: All
>             Status: NEW
>           Severity: normal
>           Priority: P2
>          Component: Framework
>         AssignedTo: fsasaki@w3.org
>         ReportedBy: dmh@tibco.com
>          QAContact: public-ws-policy-qa@w3.org
> 
> 
> It is not clear which of three operations is meant in the statement 
> (in section
> 4.5) that "If two alternatives are compatible, their intersection is an
> alternative containing all of the assertions in both alternatives". I 
can see
> four significantly different possible interpretations of this.  Suppose
> alternative 1 consists of [A B B C C C] and alternative 2 consists of [B 
C C D
> D].  Then the "intersection" of these could be
> 
> * Bag union: [A B B B C C C C C D D] (all occurrences of all assertions 
from 1
> together with all occurrences of all assertions from 2)
> * Bag intersection: [B C C] (A is not in both, B occurs (at least) once 
in
> both, C occurs (at least) twice in both, D is not in both)
> * Set union: {A B C D} (all assertions from 1 together with all 
> assertions from
> 2)
> * Set intersection: {B C} (all assertions occurring in both 1 and 2).
> 
> Though set intersection and set union seem to match the text most 
closely, it
> seems unlikely that this is what is meant, given that alternatives 
> are bags and
> multiplicity is in some way significant.
> 
> The spec should say explicitly which operation is meant.
> 
> 
Received on Tuesday, 22 May 2007 20:50:36 UTC

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