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Re: Semantic web formalisms (was Re: Requirements for a possible "RDF 2.0")

From: Adrian Walker <adriandwalker@gmail.com>
Date: Fri, 15 Jan 2010 17:44:40 -0500
Message-ID: <1e89d6a41001151444y3fa084bew1645d49390c30467@mail.gmail.com>
To: Jiří Procházka <ojirio@gmail.com>
Cc: semantic-web@w3.org, Pat Hayes <phayes@ihmc.us>
Hi Jiří --

You wrote:

*Still information in RDF which is using ontology that is defined just by
natural language (not descriptive - OWL) are worth something and up to a
certain point can be processed by machines... *

Actually, one can drop the "up to a certain point" qualifier, and say
"*can*be processed by machines" .

Here's how.  We can keep RDF simple, and write the "ontology" in executable,
open vocabulary English.

Here's an example that you can view, run and change using a browser,

www.reengineeringllc.com/demo_agents/RDFQueryLangComparison1.agent

and here is a paper describing the underlying online system

www.reengineeringllc.com/A_Wiki_for_Business_Rules_in_Open_Vocabulary_Executable_English.pdf

The alert reader of the above paper will notice an interesting parallel with
Pat Hayes' recent talk, in which the ungainly fragments in the middle 80% of
the semantic web layer cake were replaced with a single elegant technology.

                              -- Adrian

Internet Business Logic
A Wiki and SOA Endpoint for Executable Open Vocabulary English over SQL and
RDF
Online at www.reengineeringllc.com    Shared use is free, and there are no
advertisements

Adrian Walker
Reengineering


                                    -- Adrian





2010/1/15 Jiří Procházka <ojirio@gmail.com>

> On 01/15/2010 05:36 PM, Pat Hayes wrote:
> >
> > On Jan 15, 2010, at 1:58 AM, Jiří Procházka wrote:
> >
> >> On 01/15/2010 08:06 AM, Pat Hayes wrote:
> >>>
> >>> On Jan 15, 2010, at 12:32 AM, Jiří Procházka wrote:
> >>>
> >>>> On 01/15/2010 06:29 AM, Pat Hayes wrote:
> >>>>>
> >>>>> On Jan 14, 2010, at 10:50 PM, Jiří Procházka wrote:
> >>>>>
> >>>>>> On 01/15/2010 04:17 AM, Pat Hayes wrote:
> >>>>>>>
> >>>>>>> <rant>
> >>>>>>> This brings up a broader issue. Everyone agrees its good to keep
> RDF
> >>>>>>> simple. But keeping RDF simple by making it in effect into a
> >>>>>>> general-purpose construction kit, and then expecting that as a
> >>>>>>> matter of
> >>>>>>> routine people will use the constructions, isn't really being
> honest
> >>>>>>> about 'simple'. OWL/RDF is a lot less simple than RDF itself
> largely
> >>>>>>> because its written in what we might more honestly call
> >>>>>>> OWL-syntax-coded-in-lists-described-using-RDF, which IMO isn't
> >>>>>>> really
> >>>>>>> RDF any more. If we want to expect RDF to do this kind of thing,
> >>>>>>> then it
> >>>>>>> ought to have a whole datastructuring facility built in explicitly,
> >>>>>>> perhaps along JSON lines, rather than prostituting the triple
> >>>>>>> store to
> >>>>>>> be a data structuring tool.
> >>>>>>> </rant>
> >>>>>>
> >>>>>> Wasn't this the whole idea of RDF? Simple language for expressing
> any
> >>>>>> information? Doesn't it use triples, simple relations between two
> >>>>>> objects, specifically for the reason that it is universal, and any
> >>>>>> kind
> >>>>>> of structure can be expressed by it?
> >>>>>
> >>>>> There are two notions of universal here, and we shouldn't get them
> >>>>> confused. One is a universal programming language, which can be
> >>>>> used to
> >>>>> build arbitrary data structures and define operations over them. In
> >>>>> other words, in fact, a programming language. The other sense is a
> >>>>> universal *descriptive* language, which RDF is supposed to be , but
> >>>>> isn't because it is too simple. (Thats why we need OWL, etc.;
> >>>>> though RDF
> >>>>> is closer than I used to think, see my ISWC talk.)
> >>>>>
> >>>>> My point was only that if RDF needs to *use* sequences (like, as data
> >>>>> structures to encode OWL syntax, for example, or as a way of hacking
> >>>>> N-ary relations using only binary links) then this is more like
> >>>>> building
> >>>>> data structures than describing anything, and maybe it would be
> better
> >>>>> to admit this up front and deal with it with a real datatstructuring
> >>>>> notation. It wasn't the whole idea of RDF to have it be a kind of
> >>>>> awkward version of simplified LISP.
> >>>>
> >>>> No, I am not mixing in programming languages, I am talking about
> >>>> descriptive language, though I am not a logician, so could you please
> >>>> explain what universal descriptive language needs to fulfill (or
> >>>> provide
> >>>> a link to such explanation)? I cannot imagine anything that cannot be
> >>>> described by RDF+RDFS - you say we need OWL - but OWL is defined using
> >>>> RDF+RDFS.
> >>>
> >>> No, its not!  OWL is a different language from RDF, and its not defined
> >>> in RDF. In fact, it couldn't be defined in RDF, since RDF is not
> >>> expressive enough. Both RDFS and OWL/RDF are semantic extensions of
> RDF,
> >>> but that means that they need 'extra' semantics in addition to that
> >>> provided by RDF. In the case of OWL/RDF, it wasn't at all easy to
> >>> specify this stuff and keep it consistent with the RDF meanings.
> >>
> >> Now things clears up!
> >> I think we differ in that, that I consider every RDF vocabulary a
> >> semantic extension. You can describe things using descriptive languages
> >> like OWL or RDFS, but also using natural language.
> >
> > True, but what then is the purpose of RDF? Why don't we just use English
> > as the semantic web formalism? This seems to me to be the reductio ad
> > absurdum of your point of view. The idea of the SWeb is that semantic
> > information written in RDF can be processed by machines. And the
> > technology of RDFS, OWL, SPARQL etc. depends entirely upon genuine
> > semantic extensions (as defined in the spec itself) , not just a
> > let-it-all-hang-out idea that anything comment written anywhere can
> > count as an RDF-defined meaning postulate.
>
> Still information in RDF which is using ontology that is defined just by
> natural language (not descriptive - OWL) are worth something and up to a
> certain point can be processed by machines - an engineer has to teach
> his application the ontology.
>
> Look at FOAF for example... Undoubtedly there is demand for such
> lightweight semantics. If it was to be defined by some descriptive
> language... to be frank, I can't imagine that - it would probably be
> some upper ontology stuff which is subject of many disagreements. That
> is why we shouldn't embrace one specific descriptive language as main
> RDF formalism, we should be able to choose it, therefore defining the
> level our ontologies can be reasoned about by machines. Saying something
> like "DL should be good enough for everyone" might be a mistake...
>
> As I understand it, you expect to teach your machine RDF, and be able to
> "understand" whole semantic web. My view is I have to continuously teach
> it new formalism which are starting to get used on the web (unless they
> are defined by some formalism it already understands).
>
> I'm all for having a widely used and W3C blessed ontology for defining
> ontologies using set theory and formal logic, on top of RDF, but not as
> a part of it. I guess it's mainly a question of proper modular design
> and low barrier of entry, since I don't know of any competing logic
> theories to be honest, but I expect there are some or will be in future.
>
> Best,
> Jiri
>
> PS: Others: Sorry for confusion, 3 mails accidentally went off list,
> they are quoted here of course.
>
> >> In any case your
> >> description is just a imperfect surrogate of your view of the described
> >> things (depending how deep is your understanding and how good is your
> >> skill with the descriptive/natural language) which is a surrogate of the
> >> things themselves (depends what philosophy you subscribe to).
> >> If we want RDF to be universal information interchange language, we
> >> shouldn't bless one way of reasoning about things (DL) or enforce usage
> >> of some top-level ontology (which is essentially the same thing), and
> >> expect data to be semantic mess like minds of all people put together...
> >>
> >>>> Anyway you probably meant the universal descriptive language has to be
> >>>> able to describe anything using only it's own terms, be self-hosted
> >>>> (bootstrapped), not aided by natural language like with RDFS.
> >>>
> >>> RDFS is defined by the RDFS semantic conditions, not by natural
> language
> >>
> >> And how are these semantic conditions defined?
> >
> > Using *mathematics*. And this is not a joke: although the math may be
> > written in English, the only aspects of English meaning that it relies
> > upon are those that define the meanings of terms in set theory and
> > formal logic.
> >
> >>
> >> Best,
> >> Jiri
> >>
> >> PS: You took the discussion off list, dunno if it's intentional
> >
> > No, it wasnt intentional. But whatever :-)
> >
> >> , any way
> >> is good with me. Maybe will write a blog post someday about what I learn
> >> from you.
> >>
> >>
> >>>> I don't see why it needs to be that way, in fact I see that as its
> >>>> strength - we can use it to describe things with various levels of
> >>>> detail. For example I can define simply:
> >>>>
> >>>> <NaturalNumbers> a rdfs:Class ;
> >>>> rdfs:comment "A class of natural numbers - integers which are greater
> >>>> than zero" .
> >>>
> >>> But you still need some way to actually write the numbers down, ie some
> >>> numerical convention. There are several of them, so you need to say
> >>> which one you are using. Now you have datatyped literals.
> >>>
> >>>>
> >>>> Or I could use OWL and express formally it's relation to integers,
> >>>> but I
> >>>> don't need to.
> >>>>
> >>>>>> Why should we give preferential
> >>>>>> treatment to relations describing structure than those describing
> >>>>>> time,
> >>>>>> measures, events, organizations, people, pizzas...?
> >>>>>
> >>>>> Because they aren't *descriptions* of structure, they are structures
> >>>>> being used to describe other things. Just like triples are.
> >>>>
> >>>> I believe triples were chosen because they are the simplest of the
> >>>> structures, yet can describe any other.
> >>>
> >>> They are simplest and extremely useful, yes. But using them to
> >>> *describe* others, which are then also themselves used to describe
> other
> >>> things, gets the syntax/semantic levels all mixed up.
> >>>
> >>>>
> >>>> Do you intend to define all structures possible which can be used to
> >>>> describe other things?
> >>>>
> >>>>>> This is what I always thought what RDF was supposed to be and things
> >>>>>> like containers, blank nodes, literal data types, language tags
> >>>>>> got in
> >>>>>> because of pragmatical reasons, mainly to give users some kind of
> >>>>>> direction, examples how to get started.
> >>>>>
> >>>>> Well, not really. All of these things are needed in order to describe
> >>>>> things that people wanted to describe, and couldn't be described any
> >>>>> other way. If you don't have literals, how are you going to use
> >>>>> numbers
> >>>>> in a description? Without language tags, how are you going to say
> that
> >>>>> something is written in French? Well, OK, maybe containers...
> >>>>
> >>>> <data:text/plain;charset=utf-8,Je%20ne%20comprends%20pas.> ex:language
> >>>> lang:French .
> >>>
> >>> Well, OK, but you essentially have the lang tags here as language
> >>> 'classes'. Whats the advantage? If these are part of the language, then
> >>> they are just more longwinded tags. If  they aren't, then what "knows"
> >>> that lang:French means French? (RDF doesn't know this, right?)
> >>>
> >>> I think we did try out a design like this with language properties. But
> >>> you have to say what it means when the language information is missing.
> >>> Tags in literals make it compulsory, which is good for some purposes.
> >>>
> >>>>
> >>>> I don't advocate using data URI scheme instead of literals, but it
> >>>> should be possible.
> >>>> Maybe you are right about the blank nodes though, I am not sure if
> this
> >>>> would work (meaning the URI is irrelevant):
> >>>>
> >>>> <j48fd8dj3> rdf:type ex:UnnamedNode .
> >>>
> >>> No, that confuses use and mention. The thing denoted isn't a blank
> node.
> >>>
> >>>>
> >>>>>> Reality that even such thing as RDFS was made separate of the RDF
> >>>>>> itself
> >>>>>> support my view (even though I suspect one of reasons if that
> >>>>>> separation
> >>>>>> was the process of it's development).
> >>>>>
> >>>>> Yes, most the latter. I would have preferred to have one namespace,
> >>>>> but
> >>>>> this was set in stone very early on.
> >>>>>
> >>>>>>
> >>>>>> On the other hand I am not against creating community developed
> >>>>>> framework for making common uses of Semantic Web technologies
> easier,
> >>>>>> defining useful structures and design patterns... but build that *on
> >>>>>> top* of RDF as separate framework.
> >>>>>>
> >>>>>> I would like RDF to be as lightweight (low level) as possible - if I
> >>>>>> were to make mine RDF, there would be no containers, bnodes, literal
> >>>>>> data types, language tags, maybe even no literals - using data URI
> >>>>>> scheme. Anyway I value compatibility and adoption more than
> >>>>>> sticking to
> >>>>>> my view of the world so I use RDF as it is.
> >>>>>>
> >>>>>> Other alternative would be to have the low level core, build
> >>>>>> modules on
> >>>>>> top of it, for example like some programming languages do (Python,
> >>>>>> Java...) and call the whole thing RDF - I guess that is what would
> >>>>>> make
> >>>>>> most people happy.
> >>>>>
> >>>>> But this whole idea of 'building modules on top' is a programming
> >>>>> idea,
> >>>>> not a description language idea. It muddles up the notion of a
> >>>>> description. Which 'level' defines the semantics you should be
> >>>>> using in
> >>>>> a query? There's no way to know.
> >>>>
> >>>> You can use any level, because all levels are defined by levels under
> >>>> them, lowest of them being RDF core.
> >>>
> >>> What do you mean by one level being "defined" by another, if these are
> >>> all descriptive languages? Do you imagine RDF core ontologies being
> used
> >>> to describe higher-level meanings? Because that (provably) will not
> >>> work: RDF isn't expressive enough. And if it were expressive enough,
> >>> then we wouldn't need the higher levels, except maybe as syntactic
> >>> sugar.
> >>>
> >>> Pat
> >>>
> >>>>
> >>>> Best,
> >>>> Jiri
> >>>>
> >>>> PS: Actually there is one thing which would aid bootstrapped nature of
> >>>> RDF:
> >>>>
> >>>> ex:contains rdf:type rdf:Property ;
> >>>> rdfs:comment "property for stating that a reified triple is part of
> >>>> graph" ;
> >>>> rdfs:range rdf:Statement .
> >>>>
> >>>>> Pat
> >>>>>
> >>>>>>
> >>>>>> Best,
> >>>>>> Jiri Prochazka
> >>>>>>
> >>>>>>>
> >>>>>>> Pat
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>>
> >>>>>>>> Rgds,
> >>>>>>>>
> >>>>>>>> -Geoff
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>
> >>>>>>> ------------------------------------------------------------
> >>>>>>> IHMC                                     (850)434 8903 or (650)494
> >>>>>>> 3973
> >>>>>>> 40 South Alcaniz St.           (850)202 4416   office
> >>>>>>> Pensacola                            (850)202 4440   fax
> >>>>>>> FL 32502                              (850)291 0667   mobile
> >>>>>>> phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>
> >>>>>
> >>>>> ------------------------------------------------------------
> >>>>> IHMC                                     (850)434 8903 or (650)494
> >>>>> 3973
> >>>>> 40 South Alcaniz St.           (850)202 4416   office
> >>>>> Pensacola                            (850)202 4440   fax
> >>>>> FL 32502                              (850)291 0667   mobile
> >>>>> phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>
> >>>
> >>> ------------------------------------------------------------
> >>> IHMC                                     (850)434 8903 or (650)494 3973
> >>> 40 South Alcaniz St.           (850)202 4416   office
> >>> Pensacola                            (850)202 4440   fax
> >>> FL 32502                              (850)291 0667   mobile
> >>> phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
> >>>
> >>>
> >>>
> >>>
> >>>
> >>
> >
> > ------------------------------------------------------------
> > IHMC                                     (850)434 8903 or (650)494 3973
> > 40 South Alcaniz St.           (850)202 4416   office
> > Pensacola                            (850)202 4440   fax
> > FL 32502                              (850)291 0667   mobile
> > phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
> >
> >
> >
> >
> >
>
>
Received on Friday, 15 January 2010 22:45:15 UTC

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