On Fri, May 31, 2013 07:04, William Frank wrote:
> On Fri, May 31, 2013 at 2:48 AM, doug foxvog <doug@xxxxxxxxxx> wrote:
>> On Tue, May 28, 2013 20:10, William Frank wrote:
>> >...
>> > For example, chardonnay is NOT a type of wine, contrary to the OWL
>> > tutorial. Chardonnay is a type of grape, and a wine may be classified
>> > according the grapes used to make it, as well as in myrid other ways. (01)
>> If wines my be classified according to the types of grapes used to make
>> them, why do you object to these "classes" of wines being called "types"
>> of wine? (02)
> Perhaps what I am saying and what you say about acyclic directed graphs
> are close. I also suspect I am missing something. (03)
> I find It much more flexible and requiring less baggage to treat the huge
> variety of classification schemes (schemes such as color, region, etc.)
> according to which something (such as Wine) can be classified, and all the
> classifiers in each scheme (red, white, burgundy, chardonnay), as
> themselves part of the model, and their definitions, at the same level as
> the wines themselves. Instead of chardonnay being a 'type' of wine, if
> instead we define the wine grape classification scheme and the classifier
> chardonnay, as for all x:wine charadonnay(x) iff (the grapes from which x
> were made were at least 50% chardonnay grapes). Then, I would want to
> say, this wine **is classified as a* that classifer, Both the classifier
> and the thing classified existing at the same logical level, and in the
> *is classified as a* being the logical relation between them. (04)
You are distinguishing between *is a* (or *is an instance of* for those
use "is a" to mean "is a type of") and *is classified as a*. Reading your
email, i have not seen the need for such a distinction. (05)
> At the same time, I have found that it is useful to construct a single,
> quite shallow natural type hierarchy, easy for bilogical obects like
> grapes, (06)
You were earlier supporting biological taxonomies as a method of
defining a hierarchy. However, such a hierarchy is often quite deep.
Modern humans are classified by this taxonomic hierarchy as
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Craniata
Subphylum: Vertebrata
Superclass: Tetrapoda
Clade: Amniota
Clade: Mammaliaformes
Class: Mammalia
Infraclass: Eutheria
Superorder: Euarchontoglires
Order: Primates
Infraorder: Simiiformes
Superfamily: Hominoidea
Family: Hominidae
Subfamily: Homininae
Tribe: Hominini
Genus: Homo
Species: sapiens
Subspecies: sapiens (07)
Each taxon here is a natural subtype of the taxon above it. (08)
The utility of hierarchies is that everything that is true of all instances
of one class is true of all instances of its subclasses. Note that i'm
referring to properties of the *instances* of the class, not the properties
of the *class* itself. A class would certainly have different properties
than its subclasses. (09)
What is your objection to a deeper hierarchy of types in contexts
in which they can be useful? (010)
> and not so hard for some things like wine, where we can define what
> it means to be a wine, (manufacture method), natural wines, fortified
> wines, perhaps as the two first nodes. (011)
A blended wine would have a different manufacturing method. (012)
> I heard here not long ago that
> figuring out what was the right core hierachy for minerals
> was not so obvious to all, but many of the other descritors, (013)
The problem here is defining a "right core hierarchy" with the assumption
that there is only one. So long as one allows multiple hierarchies,
which is the right "core" one ceases to be an issue. (014)
> such as hardness, I would treat differently. (015)
Mineral hardness would be a property of a class that implies a
property of every instance of the class. Note that there a handful
of different types of hardness, each with their corresponding scales. (016)
Since many minerals are combinations of substances, class properties
often are a range, meaning that the corresponding instance properties
of different instances can be expected to differ -- but to remain within
the range for the class property. (017)
> For things like financial instruments, there is a very
> shallow hierachy based on the nature of the obligation and rights
> involved,
> while all the virtually infinite varieties of financial instruments are
> better distinquished by the parts they are assembled from,
> and the features of those parts. (018)
Fine. I have done little work in this area. (019)
If some regulatory agency defines a type of instrument that a certain
regulation applies to, then it would be useful for all the specific types
of instruments that fall within that definition to be specified as subclasses
of that type. (020)
> I have found the classifications of them ineffective if
> done with multiple types (it becomes almost like a fine wire mesh), rather
> than with simple definitions of what it means, for instance, to be a sushi
> bond or a PIK bond. This idea of natural types I do not know how to
> easily argue for, though I have seen such arguments that convinced me. (021)
I wouldn't apply the term "natural" to anything constructed by humans --
certainly not financial instruments. (022)
> Me, I only find it effective. (023)
>> I have often criticized the wine tutorial, but i do not find this to be
>> one of its problems. (024)
>> > These are not different 'types" of wine, using the bilogical analogy
>> > for taxonomies. (025)
>> Formal ontology has long since moved past taxonomy trees. It is
>> much more useful to use directed acyclic graphs. (026)
>> > Wine would have only ONE subtype hierachy, based on
>> > what is essential about wine being wine. (How it is made). (027)
>> One valid subtype hierarchy of types of wine is based on the type of
>> grape. Another (single level) hierarchy of wine type is by color. A
>> third is regional. A regional division of wine types by vineyard might
>> be useful at some level of business, but a further division by vineyard
>> and grape variety provides a useful disjoint set of types of wine. This
>> hierarchy of types can be taken one step further -- by vintage year. (028)
> Of course, if one wishes to use the type concept in this way, this is
> right, so I am seeing that my criticism of the wine tutorial is perhaps
> misplaced. Perhaps I simply am not happy with the way the authors
> of OWL want to use OWL. (029)
Join the club. 8)# (030)
> Perhaps I am arguing more against official UML semantics,
> and OWL has nothing to do with it. For in UML, it seems that they have
> striated the world into so many levels each of which requires a different
> model, when in fact it is much simpler to consider the ways we classify
> things to be things too. (031)
Yes. The ways we classify things are themselves things. Hierarchy
systems are things. Not only are the hierarchies things, but the
classes themselves are things. An ontology should enable the statement
of properties of classes, and relationships among classes. (032)
To use biological taxonomy as an example: (033)
* Homo is a genus
* Homo rhodeniensus is a species
* Homo sapiens is a species
* Homo sapiens and Homo rhodeniensus are disjoint
* Homo rhodeniensus is extinct (currently)
* Homo sapiens decends from Homo rhodeniensus (034)
Note that in a biological taxonomy, there are different types of classes.
Once you define these types, each class may be understood better by
knowing which type it is, i.e., which metaclass(es) it is an instance of. (035)
The basic biological types in the animal taxonomy are species,
tribe, genus, family, order, class, phylum, kingdom, and domain,
along with sub- and super- versions of many of these. Different
types at the same level are disjoint, i.e., they do not share instances. (036)
There are other, much shallower classifications of organisms that are
mostly orthogonal to the hierarchy of biological taxons. For example,
organism by gender, organism by natural diet. One can encode
useful information about classes such FemaleAnimal or Insectivore
that cut across the taxon hierarchy. (037)
Once you realize that you can specify properties and interrelationships
among classes, you might be less resistant to accepting more of them. (038)
> If you could help me get to the bottom of this, I would be most grateful. (039)
I hope this was of some help. (040)
-- doug f (041)
> Wm (042)
>> >> ...
>> >
>> > --
>> > William Frank
>> >
>> > 413/376-8167
>>
>>
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