W3C home > Mailing lists > Public > www-webont-wg@w3.org > March 2003

comments on Overview and Guide

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Mon, 17 Mar 2003 12:15:47 -0500 (EST)
Message-Id: <20030317.121547.68329283.pfps@research.bell-labs.com>
To: www-webont-wg@w3.org


	Comments on Overview and Guide

(I'm waiting for the new version of Reference before providing comments.)


- title - I changed to 
		OWL Web Ontology Language
		Semantics and Abstract Syntax
	  on the suggestion of Jim Hendler.  This makes it clear that OWL
	  is not a misspelling of an acronym.  I suggest that we again
          revisit the idea of a common way of naming the documents.


Comments on ``Web Ontology Language (OWL): Overview'' dated ``W3C Working
Draft 4 March 2003''.

general comment - I STRONGLY suggest using owl: for all OWL terms.
  	Reference and Semantics and Abstract Syntax already do so.
	Guide mostly does so also.

general comment - I again suggest removing Section 2.  In my opinion,
	Section 2 is decidedly harmful.  Note in particular, the bare
	inclusion of intersectionOf in Section 2.1.  How will this be
	understood by readers?  If a language synopsis is needed, it could
	be an appendix.

general comment - I remain skeptical as to the utility of this document.
	Maybe it is because I do understand OWL, but I find that when
	reading this document I end up with many more questions than
	answers. 

missing - annotations
	- name separation in OWL Lite
	- ObjectProperty and DatatypeProperty separation in OWL Lite
	- oneOf over data values
	- references section

title - I suggest
		The OWL Web Ontology Language: Overview
	
abstract - I suggest starting
		The OWL Web Ontology Language is designed for use by
		applications that need to process the content of
		information instead of just presenting information to
		humans.  

web vs Web - I think that ``Web'' is supposed to be used instead of
	       ``web''. 

abstract - I suggest 
		OWL has three increasingly-expressive sublanguages: OWL
		Lite, OWL DL, and OWL Full.

abstract - OWL Semantics and Abstract Syntax

status - I suggest
		This overview ... herein are provided to help understand
		OWL, but may not ... OWL Semantics and Abstract Syntax.

1. - I suggest
	The document describes the OWL Web Ontology Language.  OWL
	is intended to be used when the information contained in
	documents needs to be processed by applications, as opposed
	to situations where the content only needs to be presented
	to humans. ... is called an ontology.  

1.1 - I suggest
	The following ... .
	- This overview ... .
	- The OWL Guide ... .
	- The OWL Reference ... .
	- The OWL Semantics and Abstract Syntax ... .

1.2 - I suggest
	... The first level above RDF required for the Semantic Web is an
	ontology language what can formally describe the meaning of
	terminology used in Web documents.  ... OWL Use Cases and
	Requirement provides ... for a Web Ontology Langauge.

	OWL has been designed to meet this need for a Web Ontology Language.
	OWL is part of the growing stack of W3C recommendations related to
	the Semantic Web.

	(don't use a dl here, instead use a ul, as in Section 1.3)

1.3 - I suggest

	OWL Lite ... constraints, OWL Lite ... and OWL Lite provides ...

	OWL DL ... want maximum expressiveness while retaining
	computational ... 

	OWL Full ... unlikely that any reasoning software will be able to
	support complete reasoning for every feature of OWL Full.

	... users require the more-expressive constructs provided by OWL
	DL. ... e.g., ... classes or attaching 

	... Every OWL (...) document ...

1.4 - I suggest

	... features of OWL Lite ... OWL Full.  OWL DL and ... .

2 - I suggest

	This section provides ....

2 - See comment on using owl:

2.1 - I suggest

	The list ... is given below.

2.1 - The RDF Schema Features list is confusing to me.  What does
        Individual ... have to do with RDF Schema?

2.1 - Something needs to be added on datatypes.

2.2 - I suggest that the HTML source be modified to give much less
	spacing

2.2 - I suggest
	The list ... is

3 - I suggest
	... has more limitations on the use of the features than OWL DL or
	OWL Full.  In OWL Lite classes ... (cannot be arbitrary
	expressions), ... are also only allowed between named classes,
	... Similarly, restrictions

3.1 - The links under SubClassOf and AllValuesFrom are not appropriate.

3.1 - I suggest
	owl:Class: ... owl:Thing ... a superclass of all OWL classes.

3.1 - I suggest
	rdfs:subClassOf: ... subclass of another class. ... if an individual is a
	Person, then it is also a Mammal.

3.1 - I suggest
	rdf:Property:  Properties can be used to state relationships between
	individuals or from individuals to data values.  ... include
	hasChild, .... The first three can be used to relate ....  The last
	(hasAge) can be used to relate ...

3.1 - I suggest
	rdfs:subPropertyOf: .... that if an individual is related to
	another ..., then it is also related to the other by ....

3.1 - I suggest
	rdfs:domain:  A domain of a property limits the individuals to
	which the property can be applied.  If a property relates an
	individual to another, and the property has a class as one of its
	domains, then the individual must belong to the class.

3.1 - I suggest a similar change for rdfs:range


3.2 - I suggest
	owl:equivalentClass: Two classes may be stated to be equivalent.
	Equivalent classes have the same instances. ...

3.2 - I suggest a similar change for equivalentProperty

3.3 - I suggest not using SSN as an inverse functional property example, as
      it could be misconstrued as implying that OWL Lite allows inverse
      functional on datatype properties.

3.4 - I suggest merging 3.4 and 3.5

3.4 - I suggest
	OWL Lite allows restrictions to be placed on how properties can be
	used by instances of a class. The first two kinds of restrictions
	limit which values can be used, the last three kinds limit how may
	values can be used.

3.4 and 3.5 - I suggest rewriting all five points to fit with the
	introductory wording above.

3.7 - I suggest something like:
	OWL uses the RDF mechanisms for data values.  See the OWL Guide for
	more information.

3.8 - I suggest 
	OWL Lite supports notions of ontology inclusion and relationships
	and attaching information to ontologies.  See OWL Reference for
	details and OWL Guide for examples.

5. - I suggest
	... Web ...

5. - The acknowledgments should go in an Acknowledgments section.
	



Comments on ``Web Ontology Language (OWL) Guide Version 1.0'' dated ``W3C Working
Draft 9 March 2003''.

general question - Why are Overview Section 1.3 and Guide Section 1.1 so
		similar?

general comment - It is OWL Semantics and Abstract Syntax, not OWL Abstract
		Syntax and Semantics.

web vs Web - I think that ``Web'' is supposed to be used instead of
	       ``web''. 

title - I suggest
		The OWL Web Ontology Language: Guide

abstract - I suggest
	The OWL Web Ontology Language is intended ....

missing - oneOf on datavalues

1 - I suggest no paragraph break before ``To support ...''.

1 - I suggest
	The OWL Web Ontology Language is a language ...

1 - I suggest
	An OWL ontology may include information about classes, properties,
	and their instances.

1.1 - I suggest
	... while OWL Lite supports ... and provide a quick ...

2 - I suggest
	OWL is ... content.

	OWL collects related information into ontologies.
	An OWL ontology is mostly a collection of information about
	classes, properties, and their instances.  

	As OWL is part of the Semantic Web, and the Semantic Web is
	inherently distributed, OWL must allow for information to be
	gathered from distributed sources.  This is partly done by allowing
	ontologies to be related, including explicitly importing
	information from other ontologies.

	The other way that OWL deals with distributed information is by
	working within an open world framework.  In OWL, information about
	a resource is generally not assumed to be complete.  While a class
	or individual can be introduced in a particular ontology and
	information about the class or individual can be given there,
	information about the class or individual can also be given in
	other places.  New information can only extend
	previously-encountered information, never override it, making OWL a
	monotonic formalism.

	New information can contradict previously-encountered information,
	but even this situation does not result in the
	previously-encoutered information being overriden, instead
	resulting in a formal contradiction.  The possibility of such
	contradictions is something that a designer of an ontology needs to
	take into consideration.  Is is expected that tool support will
	help detect such cases.

2.1 - I suggest
	Before we can use a set of terms in OWL, ....

2.1 - I suggest
	OWL depends on constructs defined by RDF, RDFS, and XML Schema
	datatypes. ...

2.2 - I suggest
	The owl:Ontology element ...

2.2 - I think that it is ``xml:base''.

2.2 - I suggest
	... mechanisms.  Namespace declarations provide .... indicate the
	intention to include ...

2.3 - It is ``rdf:about''.

2.3 - I suggest
	Properties that are used as general annotations ...

2.3 - I suggest removing the paragraph on </owl:Ontology> this closing tag
	is given above.

2.3 - I suggest
	is ultimately closed by
		</rdf:RDF>
	which closes the namespace declaration shown above.

3 - It is generally not a good idea to start a section with a subsection
    heading.  I suggest starting this section as

	3. Basic Ontology Information

	Much of the information in an OWL ontology concerns classes, properties,
	instances of classes, and relationships between these instances.
	Some notions of ontology only permits the first two kinds of
	information allowed in an OWL ontology, but OWL also allows
	information to be specified about particular individuals.
	
3.1.1 - I suggest
	3.1.1 Simple Named Classes
	owl:Class, rdfs:subClassOf

3.1.1 - I suggest
	... In particular, we will have more to say about Winery later.

	The syntax rdf:ID="Region" is used to introduce a name.  This is
	...

3.1.1 - I suggest
	It is possible to refer to 

3.1.1 - I suggest
	... using its full URI, here ...

3.1.1 - I suggest
	The simplest taxonomic constructor for classes is rdfs:subClassOf.
	This relationship relates a more-specific class to a more-general
	class.  If X is a subclass of Y, then every instance of X is also
	an instance of Y.  The rdfs:subClassOf relationship is transitive.
	... 

3.1.1 - I suggest
	Information about a class usually also includes restrictions on
	instances of the class.  So far we have ...

3.1.2 - I suggest
	3.1.2 Individuals

3.1.2 - I suggest
	Note that the following is identical to the introduction above.	

3.1.2 - I suggest no paragraph break before ``Second, ...'.

3.1.2 - I suggest
	In order to have available a few more classes for the examples in
	the next section, we introduce ...

3.1.2 - I think that ``underly'' should be ``underlie''.

3.2 - I suggest

	3.2 Simple Properties

	This world of classes and individuals ....
	
	3.2.1 Defining Properties
	owl:ObjectProperty, owl:DatatypeProperty, rdfs:subPropertyOf,
	rdfs:domain, rdfs:range

3.2.1 - I suggest removing the sentence before ``The property
      madeFromGrape...''.

3.2.1 - I suggest removing the sentence after ``... made from at least one
      WineGrape.''

3.2.1 - Highlighting may not show up on all renderings of the document.  I
      suggest using instead
	The restriction 
 		... (include the restriction explicitly)
	defines ...

3.2.1 - Restrictions are allowed in OWL Lite, and thus should not be tagged
	as OWL DL.

3.2.1 - I suggest
	Including this restriction 

3.2.1 - I suggest avoiding the word ``cliche'' to describe simple
      restrictions.  I view it as much better to reserve ``cliche'' for
      larger constructs that could be written in several ways.

3.2.1 - I suggest
	We can now describe the class of Vintages, ...

3.2.2 - I suggest
	make use of many of the built-in XML Schema datatypes. References
	to these datatypes ... suitable ....

3.2.2 - I suggest
	... caveats described in OWL Semantics and Abstract Syntax.

3.2.2 - I suggest moving the tennisGameScore example to the end of 3.2.2.

3.2.2 - I suggest
	... We introduce the hasVintageYear ...

3.2.3 - I suggest
	First we describe Region and Winery individuals, and then we
	introduce our first wine, .... 
	
3.2.3 - I suggest
	Below we describe an instance of VintageYear ...

3.3 - I suggest
	to further specify properties and how they can be used.

3.3 - I suggest not using ``tagged''.  A much better phrase would be
      ``specified as''.

3.4 - I suggest having only one paragraph here.

3.4.1 - I suggest
	... restriction requires that ...

3.4.2 - I suggest
	... we specify Vintage ...

3.4.2 - I suggest
	We specified hasVintageYear as a functional property.

3.4.2 - I suggest removing the last sentence, as it can be confused with
	ranges like integers between 1800 and 1900.

3.4.3 - I suggest
	hasValue allows us to specify ... 

4.1 - I suggest
	4.1 Equivalence between Classes and Properties
	owl:equivalentClass, owl:equivalentProperty

	To tie together a set of ontologies it is frequently ...

4.1 - I suggest
	... owl:equivalentClass ..

4.1 - I suggest
	The property owl:equivalentClass ... have precisely the same
	instances.  Note that in OWL DL, .... ... we can use
	owl:sameIndividualAs ...

4.1 - I suggest
	... two independently developed ontologies, ...
	owl:equivalentClass ...

4.1 - I suggest
	... rdfs:subClassOf ... owl:equivalentClass ...

	... owl:equivalentClass ... 

	(etc, in this section and later in the document) 

4.2 - I suggest
	4.2. Identity between Individuals
	owl:sameIndividualAs, owl:sameAs

4.3 - I suggest
	4.3. Different Individuals
	owl:differentFrom, owl:AllDifferent

5 - I suggest
	These are called owl:....

5.1 - I suggest regularizing the subsection headings like
	5.1.1 Intersection [some uses OWL DL]
	owl:intersectionOf

	5.1.2 Union [OWL DL]
	owl:unionOf
	
	5.1.3 Complement [OWL DL]
	owl:complementOf

5.1.1 - All the examples are in OWL Lite.  I suggest adding wording that
	talks about the difference, essentially saying that some uses of
	intersection are in OWL Lite.  This will also affect the wording in
	5.1.2 and the tagging of Section 5.

5.2 - I suggest
	OWL provides the means to specify a class via

5.2 - I find the last example confusing.  I think that a complete oneOf
	  should be used.

6 - I suggest
	... The owl:priorVersion property ... 

6 - I suggest
	... likely not be allowed in a forthcoming release:

6 - Deprecation is part of OWL Lite and is not part of versioning, so I
    suggest ending the section 
	It is important to note that owl:... and owl:... have no
	additional semantics and it is up to tool ... intended.

C - I suggest
	Appendix C: An Alternative Region Ontology
    so that you don't have the connotation, for example, that one is used
    on weekdays and the other on weekends.
Received on Monday, 17 March 2003 12:15:55 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:57:58 GMT