>I opened a page, although I am reserving some rights there
>so please feel free to evolve (for progress' sake)
>http://ontolog.cim3.net/cgi-bin/wiki.pl?PaolaDiMaio/Towards_OpenOntology
>
>
>Look forward to contribution (01)
Some comments. Overall, as stated, it is an odd
combination of asking for technology which is
already routinely deployed, and asking for the
impossible. Details. (02)
1. I really don't think it makes sense to ask for (03)
"a ... set of agreed terms... that embodies and
represents and synthesizes all available, valid
knowledge that is deemed to pertain to a given
domain" (04)
It is the 'all's here that make this impossible.
One can never get ALL the available, valid
knowledge about anything. One can only hope to
get a workable amount, and attempt to keep it
unpolluted by falsehood and reasonably up to date
and so forth. Be less ambitious, and we might
have a hope of realizing the dream. (05)
Second, though, what does it mean to say that a
set of terms - what I would call a vocabulary -
can "embody" knowledge? Terms are just, well,
terms. The knowledge is represented by larger
structures - axioms, sentences, diagrams, texts,
ontologies, topic maps, whatever - which
themselves contain and use the terms and, in the
final analysis, give the terms meaning.
Identifying a set of terms is just a first - in
practice, indeed, often a preliminary - stage of
representing useful knowledge, not the final goal
or endpoint. (06)
2. Just an aside, but this sentence seems to
indicate a misunderstanding about how ontologies
are actually built these days: (07)
"Among the barrier to adoption for Ontology,
current research identifies not only different
linguistic, conceptual and cultural differences,
but also knowledge and point of view differences
that set apart academics who generally develop
ontologies and related tools and methodologies
from experts who understand lingo and the
dynamics - system developers programmers,
systems designers and end users at large." (08)
Both real ontologies and ontology standards such
as RDF and OWL are actually mostly the product of
collaborations between teams which are dominated
by 'experts' and 'system developers' rather than
'academics' (although we dwellers in the ivory
towers do play a marginal role here and there.)
Some of the most widely used ontologies are
entirely the work of 'domain experts'. In any
case, the boundaries between the academy,
business enterprise and 'end users' such as
medical researchers, the intelligence community
or weather forecasters is increasingly blurred
and indeterminate, and people move back and forth
across it with ease. So I think this particular
'barrier' is a figment of your imagination,
frankly. (09)
Back to the details. (010)
3. You want GPL or public licencing. But semantic
web ontologies are just like Web pages: they are
open to all. You can copy them using HTTP. Why do
you think that licencing is even an issue on the
Web? (011)
4. Ontologies should "declare what high-level
knowledge it references". Again, this is a
non-issue. By design, OWL ontologies may
reference ("import") other ontologies, and these
references are part of the ontology, by
definition. So yes, of course they "declare" in
this way. Do you have some other mechanism in
mind? (The "named graph" proposal allows
ontologies to make explicit assertions about
other ontologies, such as agreeing with it,
disagreeing, basing itself on it, warranting the
truth of it, etc.. ; is this what you have in
mind?) (012)
5. It should "declare what kind of
reasoning/inference supports/it is based on" .
Again, a non-issue. This is like asking that a
bridge should have a label on it saying what kind
of bridge it is. Of *course* any ontology will be
written in some language which supports some
kinds of inference. That is why such language
specifications include a detailed semantics.
Given this, then, what this amounts to is that
the ontology should identify what language it is
written in. Which is a good idea, but again a
solved problem, so a non-issue, at least if it is
written using XML; since the XML spec provides
for just such declarations using the XML header. (013)
6. It should "support queries via natural
language as well as machine language" Whoah
there. Supporting queries in natural language is,
at the present time, close to science fiction. At
best it is a research ambition which is at the
cutting edge of AI research. And in practice, it
doesn't work very well (ask CyCorp about their
experiences.) It is, in any case, well beyond
what it is reasonable to ask of any kind of
standardized protocols. This is way too ambitious. (014)
(By the way, what exactly do you mean by "machine
language" here? Do you mean formal language?
Humans can learn to use formal notations.) (015)
7. "It should be 'easy to understand' by generic
users without specialized skills" Again, way too
ambitious. I'm not sure it even makes sense. If
you can't read or understand L, you won't be able
to read a text written in L. This seems obvious
whether L is English, Spanish or OWL. Is having a
grasp of Spanish a 'specialized skill'?
Personally I find OWL easier than, say, Russian. (016)
But the central point is that an ontology, by its
very nature, is ultimately a text written in some
language; and so to understand it, you have to
know that language. (And to ward off possible
misunderstanding, I'm here using 'language'
broadly to include, eg, map-making and
diagrammatic conventions; so that for example
circuit diagrams or flowcharts or social networks
displayed as graphs are all kinds of language.
The basic point still applies.) (017)
So trying to draw a contrast between 'generic
users' and 'academics' or whatever isn't helpful,
seems to me. What might be more use is to ask,
how long does it take to learn the relevant
language? Can we find ways of displaying
ontological content to make it easier to learn?
(We have been trying to do this in the COE system
for OWL, for example, and VivoMind are focusing
on CLSE 'structured English'. But you still have
to learn to use COE - it takes about a day - and
its a lot easier to read CLSE than to write it.) (018)
8. "It should include instructions on how to
relate such 'high level knowledge' to standard
knowledge representation artifacts used in
software and systems engineering, such as
entities, attributes, classes, objects,
properties, sub-properties, values and
relationships" (019)
Well, sure. But take a look at OWL: it is all
about entities (it calls them 'resources',
following a W3C nomenclature), classes,
properties, values and relationships. It has
owl:subProperty as one of its primitives. What
could be more clearly related to your list of
terms? Its primary documentation includes a
tutorial. What more do you want? (020)
But to be less rhetorical for a second, there is
a danger lurking here. The class/property/value
terminology is also used in OO programming, and
although they two uses are closely similar, there
are important distinctions which need to be got
clear. Ontology class hierarchies need not be
taxonomic, for example. So the ontology world is
not the same as the software/systems engineering
world, but it is close enough for the
similarities to sometimes obscure the differences. (021)
9. "It should be implementation independent;
this means not only usable by OWL/DAML model but
also reusable by alternative ontology languages" (022)
What does this even mean? An OWL ontology (for
example) isn't "usable" by the "OWL model", it is
*written in* OWL. It *is* an OWL text. There is a
BNF grammar for such things, so a machine can
check if it is legal OWL or not. Similarly, an
ontology written in, say, Common Logic is a CL
text. There isn't such a thing as a
language-independent representation of a language
text. (Even diagrams need to be parsable if they
are to be used by machines.) So this requirement
seems to me to be nonsensical as it stands.
What might make sense is to require that ontology
languages be inter-translatable. I agree, and
indeed a great deal of my effort over the past
few years has been towards bringing about this
desirable state of affairs, culminating in the
IKL notation. But this is a requirement on
ontology language standards, not on ontologies.
And it is basically impossible to enforce, other
than by exhortation, since what can stop a
person, company or working group from inventing a
new, incompatible, notation? (As for example the
business rules community recently did, with a
standard notation SBVR based, regrettably, on
modal logic.) (023)
10."it should support one view of the world if
required, and allow for simultaneous multiple
views, meaning that it should aim to be perfectly
elastic, flexible and adaptable,"
I'm not sure what this means, but it sounds
either trivial or impossible. Clearly, an
ontology may be written with one world-view in
mind, as it were, and so make distinctions (or
fail to make them), assign classifications,
quantify over a universe, etc., based on this
'world-view', that of its composer. In fact, it
is difficult to see how this can be avoided, or
what it would mean for it to be false. That is
the trivial sense. More ambitiously, one might
claim that an ontology *completely defines* one
particular world-view, in the sense that it says
so much that it allows for only one possible
interpretation (this is obviously related to the
first point about containing all the information
about some topic). And this is impossible; in
fact, in most cases, *provably* impossible. (024)
It may be that what you mean here is something in
between these two extremes, but in that case I
don't know what it is that you do mean, and some
more exposition would be very useful. (Experience
with being on committees writing standards has
shown that loosely written or imprecise
requirements can be very harmful to progress, as
they fail to serve their most useful purpose: to
limit endless discussion about what exactly
people mean, and focus effort on getting
technical issues clear.) (025)
-------- (026)
In spite of all the above, I think it is a very
good idea to try to get the requirements clear,
and that this is a good start: thanks! (027)
Pat Hayes (028)
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