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Re: Proposed minor amendments to RDF 1.1 Semantics §5

From: Pat Hayes <phayes@ihmc.us>
Date: Sat, 29 Jul 2017 12:24:56 -0700
Cc: Antoine Zimmermann <antoine.zimmermann@emse.fr>, Sam Kuper <sam.kuper@uclmail.net>, public-rdf-comments@w3.org
Message-Id: <645C3736-B028-446B-9C6A-B7B1998BCD9F@ihmc.us>
To: Ivan Herman <ivan@w3.org>

> On Jul 29, 2017, at 12:29 AM, Ivan Herman <ivan@w3.org> wrote:
> 
> Pat, Antoine,
> 
> should I interpret this by saying that the original report should be added to the official errata[1], to be considered by a future Working Group or any other type of refresh of the Recommendations?

Hmm. It hardly amounts to an erratum, more like an editorial suggestion. But if that is the only way to record it, then so be it. 

Pat

> 
> Ivan
> 
> 
> [1] https://www.w3.org/2001/sw/wiki/RDF1.1_Errata
> 
> 
>> On 29 Jul 2017, at 07:50, Pat Hayes <phayes@ihmc.us> wrote:
>> 
>> Just to be on the record as editor, I agree with Antoine’s responses here. Both of Sam's suggested edits are reasonable suggestions, but neither of them are necessary. No other readers or critics of the documents have found these passages to be ambiguous or unclear. As the process of changing a Recommendation is laborious and expensive, these suggestions should be tabled and brought to the attention of any future WG tasked with revising the RDF standard.
>> 
>> Pat Hayes
>> 
>>> On Jul 27, 2017, at 2:25 PM, Antoine Zimmermann <antoine.zimmermann@emse.fr> wrote:
>>> 
>>> Dear Sam,
>>> 
>>> 
>>> On 27/07/2017 19:00, Sam Kuper wrote:
>>>> RDF 1.1 Semantics §5 says[1]:
>>>> 
>>>> "IEXT(x), called the extension of x, is a set of pairs which identify
>>>> the arguments for which the property is true, that is, a binary
>>>> relational extension."
>>>> 
>>>> I propose two small amendments to this sentence.
>>>> 
>>>> 
>>>> # Proposed amendment 1
>>>> 
>>>> s/pairs/ordered pairs/
>>> 
>>> In most mathematical writing, it is common to call a pair something that has a first element and a second element. So the pair (x,y) (or "< x, y >" as written in the recommendation) is not the same as the pair (y,x) because the first elements are not the same. In other term, a pair is most often denoting an ordered pair. The notion of "ordered pair" is often used when it is important to distinguish it from an "unordered pair" which is in fact a set of two elements {a,b}. Similarly, an RDF triple (s,p,o) is an "ordered triple".
>>> 
>>> In any case, even if your notion of a pair differs from this one, the formal definition of IEXT is quite explicit about what it means because IEXT is a mapping "from IP into the powerset of IR x IR" and the notions of powerset and Cartesian product have very precise and well accepted meanings.
>>> 
>>>> 
>>>> Why? Suppose this triple is true, and is the entire graph:
>>>> 
>>>> ex:a ex:x ex:b
>>>> 
>>>> Also suppose that triple, which happens not to be part of the graph, is false:
>>>> 
>>>> ex:b ex:x ex:a
>>>> 
>>>>> From the first one, we could say, IEXT(ex:x) = {(ex:a,ex:b)}.
>>>> 
>>>>> From this in turn, if (ex:a,ex:b) is not an ordered pair, then we
>>>> could conclude that the following triple is true:
>>>> 
>>>> ex:b ex:x ex:a
>>>> 
>>>> However, it is not true (see above). So, we must consider (a,b) to be
>>>> an ordered pair.
>>>> 
>>>> If I am mistaken about this, I would be grateful for an explanation as
>>>> to the nature of my error.
>>>> 
>>>> 
>>>> # Proposed amendment 2
>>>> 
>>>> s/property/property x/
>>> 
>>> The sentence in which this appears in the section is not a definition, it's simply explaining what IEXT is representing, in informal terms. I don't think we need to be overly precise in sentences that are merely explanatory. Especially since the document is already published as a recommendation, updates and errata should be made only for actual errors.
>>> 
>>> Your reading is correct and, at that point of the document, there is no other properties than x being mentioned, so there is no possible ambiguities, IMO.
>>> 
>>> 
>>> Regards,
>>> --AZ
>>> 
>>>> Why? Because the sentence should be explicit about which property it
>>>> is referring to. My reading of the sentence is that x is a property,
>>>> and x is also the property to which the sentence is referring, but I
>>>> am not certain that my reading is correct. If it is, then the sentence
>>>> should be amended as proposed in order to make it clear that that is
>>>> indeed the correct reading.
>>>> 
>>>> Equally, if my reading is wrong, then the sentence should be amended
>>>> differently, in order to clarify the intended reading. (Do please let
>>>> me know if my reading is wrong!)
>>>> 
>>>> 
>>>> # Note and valediction
>>>> 
>>>> If you reply to this email, please CC me, as I am not subscribed to
>>>> this mailing list.
>>>> 
>>>> Many thanks!
>>>> 
>>>> [1] https://www.w3.org/TR/2014/REC-rdf11-mt-20140225/#simple-interpretations
>>>> 
>>> 
>>> 
>>> 
>> 
>> 
>> 
> 
> 
> ----
> Ivan Herman, W3C
> Publishing@W3C Technical Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> ORCID ID: http://orcid.org/0000-0003-0782-2704
> 
Received on Saturday, 29 July 2017 19:25:36 UTC

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