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Re: PROV-ISSUE-638 (TomDN): Notation of set of key-value pairs in contraints of PROV Dictionary [PROV-DICTIONARY]

From: Tom De Nies <tom.denies@ugent.be>
Date: Thu, 28 Mar 2013 15:52:05 +0100
Message-ID: <CA+=hbbe9YCMge57XhEY7T64CKJWaJXXrepm_36raDitEZ6YUEw@mail.gmail.com>
To: James Cheney <jcheney@inf.ed.ac.uk>
Cc: Paolo Missier <Paolo.Missier@ncl.ac.uk>, public-prov-wg@w3.org
I've pushed this to the editor's draft:

https://dvcs.w3.org/hg/prov/raw-file/default/dictionary/Overview.html#dictionary-constraints-notation

Note that I also made this consistent throughout the entire constraints.

Issue is now pending review.

Tom


2013/3/28 Tom De Nies <tom.denies@ugent.be>

> Ok, then I propose to keep the current notation and include the suggested
> explanation as a resolution to this issue.
>
> Perhaps we can vote on this during the telecon?
>
> Regards,
> Tom
>
> 2013/3/26 James Cheney <jcheney@inf.ed.ac.uk>
>
>> Hi,
>>
>> I think the way the constraints are currently presented is fine.  The use
>> of equality seems appropriate, provided its meaning is made clear.  But I
>> wasn't on the last call - were there objections to it?  The main potential
>> complications are:
>>
>> - do we require keys in sets of key value pairs to be associated with
>> unique values?  This is stated in D2, so good.
>> - do we allow "unknown" sets of key-value pairs, or of the existence of
>> them?  If so then reasoning about their equality could become complicated.
>>  However, we do not appear to need this, so equality of key / kv sets will
>> always amount to checking literal equality of sets, not solving equations
>> involving unknowns.
>> - are sets of keys (or key-value pairs) considered equal up to
>> reordering? e.g. {k1,k2} = {k2,k1}? Seems to be the case; including the
>> suggested explanation somewhere would help cement this.
>>
>> These might have to be revisited if this were to be pushed further or
>> incorporated into future versions of PROV, but as stated I think the
>> existing constraints ought to fold into the existing framework neatly.
>>
>> Minor comment:
>>
>> D8: Suggest KV1 should be K1 (as it is just a set of keys, being removed)
>>
>> --James
>>
>> On Mar 22, 2013, at 12:20 PM, Tom De Nies <tom.denies@ugent.be> wrote:
>>
>> Hello James, Paolo,
>>
>> do you have any suggestions for a better notation of these constructs, or
>> are you happy with the ones we have now?
>> The main issue is that the current notation deviates from what is used in
>> PROV-Constraints, and I'm not sure that we want that.
>> I'd like to resolve this issue before the telecon of 28th of March, so we
>> can release the document for internal review.
>>
>> Paul suggested during the telecon to use double equal signs '==' instead
>> of a single '=', but I am not sure this solves the issue.
>>
>> Another proposal is to include an explanatory paragraph, stating the
>> following:
>>
>>> In the constraints below, statements are made concerning the equality of
>>> sets of key-value pairs and sets of keys. For the sake of clarity, we will
>>> explain the used notations here.
>>> 1. To state that a set of  keys K1  and another set of keys K2 hold
>>> exactly the same keys, we use the notation K1 = K2.
>>> 2. To state that a set of key-value pairs KV1 and another set of
>>> key-value pairs KV2 hold exactly the same keys, with each key in KV1 mapped
>>> to exactly the same value as the same key in KV2, we use the notation KV1 =
>>> KV2.
>>> For example. the sets of keys {"k1", "k2"} and {"k1", "k3", "k4"} are
>>> not considered equal, since one of the sets holds keys the other does not.
>>> Analogously, the set of key-value pairs {("k1", e1),("k2", e2)} and the set
>>> {("k1", e2),("k2", e3)} are not considered equal, since the keys in the
>>> latter set map to different values than the same keys in the former set.
>>>
>>
>> If you could share your view on this, that'd be great.
>> Thanks in advance!
>>
>> regards,
>> Tom
>>
>> @Paolo: in response to your example below, i'd say that in the case of
>>
>> derivedByInsertionFrom(d2, d1, {(3,e1)} ),
>> derivedByInsertionFrom(d2, d1, {(4,e2)})
>>
>> KV1=KV2 does not hold (since nor the keys, nor the values are equal), and thus, this is not valid.
>>
>> 2013/3/7 Paolo Missier <Paolo.Missier@ncl.ac.uk>
>>
>>>  Hi,
>>>
>>> I went back to James' review and I am not sure what an inference that
>>> derives KV1 = KV2 means, when KV1 and KV2 are ground. For example, what do
>>> we make of
>>>
>>> derivedByInsertionFrom(d2, d1, {(3,e1)} ),
>>> derivedByInsertionFrom(d2, d1, {(4,e2)})
>>>
>>> ?
>>> I think I need to understand this better
>>>
>>> --Paolo
>>>
>>>
>>>
>>> On 07/03/2013 10:45, Provenance Working Group Issue Tracker wrote:
>>>
>>> PROV-ISSUE-638 (TomDN): Notation of set of key-value pairs in contraints of PROV Dictionary [PROV-DICTIONARY]
>>> http://www.w3.org/2011/prov/track/issues/638
>>>
>>> Raised by: Tom De Nies
>>> On product: PROV-DICTIONARY
>>>
>>> Came up in the review by James, but was agreed to be handled after the first WD release.
>>>
>>> We need to get consensus of the group whether the notation KV1=KV2 is acceptable for constraints D9, D10, D11, D12.4, and D12.5, and whether considering equalities on sets of keys/KV pairs is a potential complication.https://dvcs.w3.org/hg/prov/raw-file/default/dictionary/releases/WD-prov-dictionary-20130312/Overview.html#impossible-removal-insertion-constraint
>>>
>>>
>>>
>>>
>>> --
>>> -----------  ~oo~  --------------
>>> Paolo Missier - Paolo.Missier@newcastle.ac.uk, pmissier@acm.org
>>> School of Computing Science, Newcastle University,  UKhttp://www.cs.ncl.ac.uk/people/Paolo.Missier
>>> PGP Public key: 0x45596549  - key servers: pool.sks-keyservers.net
>>>
>>>
>>
>>
>>
>>
>> The University of Edinburgh is a charitable body, registered in
>> Scotland, with registration number SC005336.
>>
>>
>
Received on Thursday, 28 March 2013 14:52:41 UTC

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