W3C home > Mailing lists > Public > semantic-web@w3.org > August 2008

Re: Why do you want to do that?

From: Richard H. McCullough <rhm@pioneerca.com>
Date: Tue, 12 Aug 2008 11:52:18 -0700
Message-ID: <D7BBE6E84BDB4C35B182F634BA3160CD@rhm8200>
To: "Pat Hayes" <phayes@ihmc.us>
Cc: "Frank Manola" <fmanola@acm.org>, "Adam Pease" <adampease@earthlink.net>, "KR-language" <KR-language@YahooGroups.com>, "Semantic Web at W3C" <semantic-web@w3.org>

Re: Why do you want to do that?Hi Pat
Just three things I'd like to discuss here.

1. How can you guarantee that there is no order dependence
in OWL propositions?  What about
pronoun antecedents? e.g. "he" may have many different meanings
actions/interactions which cause sequential changes in time?

2. I said
  "ind" is the name of a proposition list, which is the context of the
  statement "X ismem IndividualSet;".
You said:

But that statement can appear in many different 'contexts', so the use of 
functional notation here is undefined.
I have no idea what you mean by "functional notation" ???
or why something is "undefined" ???

3. You said


No, you misunderstand me. When you say 'use', you are presumably referring 
to some kind of inference. But what determines which inferences are valid, 
in your formalism? The usual way to do this is to have a semantics which 
determines truth in an interpretation. What is your way to do it?

With respect to mKR, I have trouble understanding why models
and interpretations have any relevance.  A few days ago, I
read: Logic, 2nd edition, section 6.4 Models.  It says
an interpretation is needed to map the formal non-logical symbols into 
English names and predicates.

But in mKR, the formal symbols are English words and phrases,
so there's no interpretation needed.


Dick McCullough
Ayn Rand do speak od mKR done;
mKE do enhance od Real Intelligence done;
knowledge := man do identify od existent done;
knowledge haspart proposition list;
http://mKRmKE.org/

  ----- Original Message ----- 
  From: Pat Hayes
  To: Richard H. McCullough
  Cc: Frank Manola ; Adam Pease ; Semantic Web at W3C ; KR-language
  Sent: Tuesday, August 12, 2008 9:44 AM
  Subject: Re: Why do you want to do that?


  At 5:01 AM -0700 8/12/08, Richard H. McCullough wrote:
    Hi Pat
    We've got a lot of confusion between us right now.
    I'll do my best to straighten it out.
    See below for my answers, comments, etc.

    Dick McCullough
    Ayn Rand do speak od mKR done;
    mKE do enhance od Real Intelligence done;
    knowledge := man do identify od existent done;
    knowledge haspart proposition list;
    http://mKRmKE.org/

    ----- Original Message -----
    From: "Pat Hayes" <phayes@ihmc.us>
    To: "Richard H. McCullough" <rhm@pioneerca.com>
    Cc: "Frank Manola" <fmanola@acm.org>; "Adam Pease" 
<adampease@earthlink.net>; "Semantic Web at W3C" <semantic-web@w3.org>; 
"KR-language" <KR-language@YahooGroups.com>
    Sent: Monday, August 11, 2008 11:15 PM
    Subject: Re: Why do you want to do that?


    > At 10:56 PM -0700 8/11/08, Richard H. McCullough wrote:
    >>I finally got a few minutes to read OWL Guide 3.1.3
    >>I read that section as supporting my position.  The word "context"
    >>is mentioned
    >>several times, with the implication that X ismem IndividualSet; in
    >>one context,
    >>and X ismem ClassSet; in a different context.
    >
    > Is that actually asserted anywhere? Please give a citation.

    I said "implication".  It is not clearly asserted.  You have to read 
between the lines.
    Here is the beginning of OWL Guide, section 3.1.3.
    Note the two fragments I have put in bold type.
    In the second one, the wording "could itself be considered" implies that 
they
    again mean "in certain contexts".


  First, it means nothing of the sort. No contexts are mentioned. Second, 
this is only a tutorial guide. The actual specification documents of 
OWL/RDFS/RDF give precise semantics for these languages (actually for three 
versions of OWL, making a total of 5 distinct languages) which are normative 
rather than informative, so take precedence over anything that you conclude 
from reading between the lines of a tutorial introduction. And in RDFS and 
OWL-Full, classes are elements of other classes. In fact, in these languages 
there are classes which contain themselves as members, eg rdfs:Class does. 
And no mention of contexts anywhere.


    Note also that "could be considered" is not the same as "is".


  True, but Frank was being ultra-careful not to offend the intuitions of 
beginners who might be puzzled by elementary set theory. As I say, this is 
an introductory tutorial document, not a specification. One should not draw 
too many conclusions from the subtleties of wording.


    To correlate with the mKR language, think "could be viewed".

    QUOTE

    There are important issues regarding the distinction between a class and 
an individual in OWL. A class is simply a name and collection of properties 
that describe a set of individuals. Individuals are the members of those 
sets. Thus classes should correspond to naturally occurring sets of things 
in a domain of discourse, and individuals should correspond to actual 
entities that can be grouped into these classes.

    In building ontologies, this distinction is frequently blurred in two 
ways:

      a.. Levels of representation: It is well known that in certain 
contexts something that is obviously a class can itself be considered an 
instance of something else. For example, in the wine ontology we have the 
notion of a Grape, which is intended to denote the set of all grape 
varietals. CabernetSauvingonGrape is an example instance of this class, as 
it denotes the actual grape varietal called Cabernet Sauvignon. However, 
CabernetSauvignonGrape could itself be considered a class, the set of all 
actual Cabernet Sauvignon grapes.
      b.. Subclass vs. instance: It is very easy to confuse the instance-of 
relationship with the subclass relationship. For example, it may seem 
arbitrary to choose to make CabernetSauvignonGrape an individual that is an 
instance of Grape, as opposed to a subclass of Grape. This is not an 
arbitrary decision. The Grape class denotes the set of all grape varietals, 
and therefore any subclass of Grape should denote a subset of these 
varietals. Thus, CabernetSauvignonGrape should be considered an instance of 
Grape, and not a subclass. It does not describe a subset of Grape varietals, 
it is a grape varietal.
    UNQUOTE
    >>
    >>But a problem arises because OWL doesn't have contexts.
    >>So, apparently, the OWL solution to mix all contexts together,
    >>and ASSUME that all the propositions are still true.
    >
    > No. The OWL methodology, like that of virtually all modern logic, is
    > to define a formal semantics for the notation, which then DETERMINES
    > what is true and false. There are no assumptions anywhere. So there
    > isn't a problem. And there are no contexts in OWL as it isn't a
    > context-dependent language.

    The namespaces used (including rdf, rdfs, owl)
    contain propositions which are part of the context of
    every OWL "document".


  If you like that way of speaking, I see what you mean; but it is 
misleading as there is only one "context" for each language.



    Every OWL "statement" has a context, which includes the "document" 
context.


  No, it *is* the document context, as you have defined it above.


    In a list of OWL statements, each statement is part of the context of
    the OWL statements which follow it.


  That is just technically wrong. OWL syntax is defined over RDF syntax, 
which is graph-based, so the order of statements in a document is 
irrelevant, and indeed might change when the document is transmitted. See 
the RDF Concepts paper for an introduction to graph syntax.



    The mKR language explicitly says what the context is, using the format
        at space=s, time=t, view=v { statement };

  Yes, but that is a context *in mKR*, not a context in OWL. There are no 
contexts in OWL.


    >
    >>
    >>To make this problem more apparent, we can specify the contexts
    >>
    >>    at view =  ind { X ismem IndividualSet; };
    >
    > What does that mean? What is the semantics of your formalism? Because
    > if you were to provide one, that would stop all the argument, by
    > answering the question.

    "ind" is the name of a proposition list, which is the context of the
    statement "X ismem IndividualSet;".


  But that statement can appear in many different 'contexts', so the use of 
functional notation here is undefined.



    >
    >>    at view = cls { X ismem ClassSet; };
    >>
    >>The question is: what happens when we mix the two contexts together?
    >
    > What DETERMINES what happens? How is consistency defined for your 
formal logic?

    Use all the propositions to deduce what is true, and what is false.


  No, you misunderstand me. When you say 'use', you are presumably referring 
to some kind of inference. But what determines which inferences are valid, 
in your formalism? The usual way to do this is to have a semantics which 
determines truth in an interpretation. What is your way to do it?


  If that is too hard, what inference rules do you have to perform 
deductions with?




    >
    >>
    >>Pat Hayes says
    >>    at view = mix { X ismem IndividualSet; X ismem ClassSet; };
    >
    > No, I didn't say that, as I don't speak this language. I wrote in 
English.

    Agreed.  That is the mKR paraphrase of what you wrote in English.


  But even in English, I did not refer to contexts or mixing of contexts. I 
simply said that it is consistent to say that something is both an 
individual and a class. Nothing there about contexts.


  Pat



    >
    > Pat
    >
    >>Dick McCullough says
    >>    at view = mix { not{X ismem IndividualSet;}; X ismem ClassSet; };
    >>
    >>
    >>Dick McCullough
    >>Ayn Rand do speak od mKR done;
    >>mKE do enhance od Real Intelligence done;
    >>knowledge := man do identify od existent done;
    >>knowledge haspart proposition list;
    >>http://mKRmKE.org/
    >>
    >>----- Original Message ----- From: "Frank Manola" <fmanola@acm.org>
    >>To: "Richard H. McCullough" <rhm@pioneerca.com>
    >>Sent: Friday, August 08, 2008 9:01 AM
    >>Subject: Re: Why do you want to do that?
    >>
    >>>On Aug 8, 2008, at 11:21 AM, Richard H. McCullough wrote:
    >>>
    >>>>
    >>>>Over the last six years, I have suggested a number of
    >>>>"improvements" to the RDF language.  Not one of
    >>>>my suggestions was adopted.  Apparently,
    >>>>RDF is fine just the way is, thank you!
    >>>
    >>>Yep.  That doesn't imply opposition to improvements though;  some
    >>>people think the way to provide the "improvements" they want is to
    >>>define languages "on top of" RDF (like the OWL dialects) rather
    >>>than  making those changes directly in RDF.  That way, your
    >>>"improvement"  and my improvement can possibly co-exist more nicely
    >>>:-)
    >>>
    >>>>
    >>>>
    >>>>I would now like to turn the tables, and ask
    >>>>why do you want to do that?
    >>>>I'll start with two features of RDF which seem to be popular.
    >>>>
    >>>>1. X  subClassOf  X;
    >>>>A neat mathematical property, right?
    >>>>But if you do the inferences, what it means is
    >>>>   X  sameAs  X;
    >>>>We already knew that.
    >>>>Why do you want to do that?
    >>>
    >>>I need some help with this question.  Do you think being able to
    >>>say X subClassOf Y is OK?  If so, are you asking why RDFS (not RDF,
    >>>BTW) doesn't explicitly forbid the special case of X subClassOf X?
    >>>Why do  you want to do that (i.e., test for this special case all
    >>>the time)?   Or are you asking why people *write* X subClassOf X?
    >>>
    >>>>
    >>>>
    >>>>2. X  type  Y;  X  subClassOf  Z;
    >>>>Another neat property: X is an individual and a class.
    >>>>Now I can ... What?  I don't know.
    >>>>Why do you want to do that?
    >>>
    >>>How about the example in Section 3.1.3 of the OWL Guide?
    >>>
    >>>--Frank
    >
    >
    > --
    > ---------------------------------------------------------------------
    > IHMC (850)434 8903 or (650)494 3973   home
    > 40 South Alcaniz St. (850)202 4416   office
    > Pensacola (850)202 4440   fax
    > FL 32502 (850)291 0667    cell
    > http://www.ihmc.us/users/phayes      phayesAT-SIGNihmc.us
    > http://www.flickr.com/pathayes/collections
    >
    >
    >
    >




-- 
---------------------------------------------------------------------
  IHMC               (850)434 8903 or (650)494 3973   home
  40 South Alcaniz St.       (850)202 4416   office
  Pensacola                 (850)202 4440   fax
  FL 32502                     (850)291 0667    cell
  http://www.ihmc.us/users/phayes      phayesAT-SIGNihmc.us
  http://www.flickr.com/pathayes/collections
Received on Tuesday, 12 August 2008 19:08:30 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 21:45:24 GMT