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Re: RDF Semantics Editors Draft?

From: Richard Cyganiak <richard@cyganiak.de>
Date: Sun, 13 May 2012 21:48:26 +0100
Cc: David Wood <david@3roundstones.com>, Peter F. Patel-Schneider <pfpschneider@gmail.com>, public-rdf-wg WG <public-rdf-wg@w3.org>
Message-Id: <9A524909-9443-46C6-A10B-2F797F14702D@cyganiak.de>
To: Pat Hayes <phayes@ihmc.us>
Hi Pat,

On 13 May 2012, at 07:45, Pat Hayes wrote:
> The problem with making the rules normative is that these rules are NOT in fact a good way to implement a reasoner.

Red herring. We are not talking about these rules because they may or may not be a good way of implementing a reasoner. We are talking about them because they are easier to understand for most readers. Implementers are free to use whatever approach they like as long as it produces correct results.

> I think they should be in a separate doument entirely, perhaps as part of the test cases,

This would be inappropriate. The test cases are supposed to be machine-processable so that one can have a test harness that automatically verifies an implementation.

> and no claims should be made as to their completeness, and no long and extremely opaque (and flawed) completeness proofs should be included, even in an appendix. Nobody gives a damn about completeness in any case.) 

-1. I do give a damn about the completeness of the rules.

> I am sympathetic to the idea that RDF should simply not have a formally defined semantics at all. This would solve all of these (and many other) problems at a stroke, and I could get on with other things in my life.

Pat, what is this. Everyone in this WG volunteers their time, and is free to walk away. So are you. Whether you can go on with other things in your life is entirely orthogonal to the question whether RDF has a formally defined semantics.

> model-theoretic semantics has been the accepted norm for semantic specifications in linguistics, logic, database theory and the theory of computation now for about 40 years,

Ridiculous overstatement.

> If we put a typo into an inference rule, or simply forget some special case, and a later reader notices this and publicises the error (as has indeed happened), then what basis do they have for claiming that the rule is wrong? If the rule itself is normative, then it CANNOT be wrong, even if it sanctions invalid inferences.

And making the model theory normative instead of the rules saves us from typos in the normative parts how?

>>> 2) Implementers of various specs (incl. RDF, RDF Schema, SPARQL) read it, in order to understand how their systems should behave, especially with regard to datatypes and RDFS inference.
> 
> If they are seeking a guide to how any system should *behave*, then they need to understand that semantics is not about behavior but rather about truth, satisfaction and consistency

Falsehood.

>>> 3) Authors of RDF Schema vocabularies read it, in order to understand the consequences of declaring domains, ranges, subproperties and so on.
>>> 
>>> 4) RDF newbies read it, because this is where they happened to end up after some googling or link-clicking and they don't understand the big scheme of things yet.
> 
> The second paragraph of the document starts "This is one document in a set of six (Primer, Concepts, Syntax, Semantics, Vocabulary, and Test Cases) ..." and they might then hazard a wild guess that the one called "Primer" might possibly be a better place to start. 

The paragraph you quote is from the “Status of this Document” section, which is the one that everyone who has ever seen a W3C document immediately skips because it's just boilerplate.

> If they habitually read documents without checking the first page, then I really don't think we have any responsibility for what kind of a mess they get into, frankly.

Look Pat, no one reads documents front-to-back on the web. People arrive in the middle of the document by following a link, or they scroll around until they see something that looks like a ToC and jump to the section whose title looks most relevant, or they just search within the document for the keyword of their interest.

> What would it mean to make those rules normative? Would an efficient tableax-based reasoner be then illegal?

No, why would it?

>>> I think we all agree that this is *not* the document you should be looking at in your first encounter with RDF.
> 
> If you know nothing about logical methods, inference engines, machine inference? Yes, it might not be a good starting point if you are this ignorant, indeed.

Inappropriate display of arrogance.

>> This problem could be solved easily with the insertion of some language in the introduction pointing to the Primer in the first paragraph (instead of just the Vocab and Concepts, as it does now).
> 
> See above. It refers to the primer in the second paragraph of the document. 

In the section that nobody reads. The Introduction is silent on the topic of which other documents you should already be familiar with before starting this one.

Best,
Richard




> 
> Pat
> 
>>> 
>>> Best,
>>> Richard
>>> 
>>> 
>>> 
>>>> 
>>>> peter
>>>> 
>>>> 
>>>> On 04/25/2012 11:27 AM, David Wood wrote:
>>>>> Hi Peter and Pat,
>>>>> 
>>>>> The RDF WG briefly discussed the need for an RDF Semantics editors draft at today's telecon.  I am aware that there are a lot of open issues and therefore hard to produce a draft, but perhaps it makes sense to have a single document that lists the issues in one place.
>>>>> 
>>>>> In any event, we would like to discuss this at next week's telecon if you can make it.  Thanks.
>>>>> 
>>>>> Relevant comments from IRC (no log published yet since the meeting isn't over):
>>>>> [[
>>>>> ivan: one thing that came up early was discussion to change title of RDF Semantics document, reorganize to make the rules normative and deemphasize the model-theoretic semantics AlexHall @ 11:20
>>>>> ... think it's a good thing to do but huge amount of editorial work AlexHall @ 11:20
>>>>> cygri: is there an editors draft of RDF Semantics yet? 11:21
>>>>> [no] 11:21
>>>>> cygri: given that there are larger changes to the doc, would feel better if there were an editors draft by now. 11:21
>>>>> guus: suggest we should put it on the agenda for next week
>>>>> ]]
>>>>> 
>>>>> Regards,
>>>>> Dave
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>> 
>>> 
>> 
>> 
>> 
> 
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Received on Sunday, 13 May 2012 20:49:02 GMT

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