Well, getting computers with
increasing ability to perform without humans is, I believe one
of the goals that motivates many workers with knowledge based
systems (including myself), and in other fields as well. We
hear a lot about self-driving cars, or airplane defense
systems that respond automatically to perceived threats, or
billion dollar rovers that have to negotiate uncertain terrain
on other planets. At present such systems need to be
carefully constructed for restricted domains, but increased
capability will make them more useful, and is eagerly sought
after.
My own interest is precisely to learn what
is required for systems to become as capable as humans in a
wide range of situations. Those who have immediate problems
to solve in a short time frame will find this of no direct
relevance. But if one needs to communicate **accurately**
between systems, the tactic of using a single language in the
communication process is unavoidable. For two or a small
number of systems that can agree ahead of time on meanings of
terms or data fields, that single language is effected by such
prior communication. For the case where one party puts data
on the web and another party wants to use the data without
prior communication with the first party, the user still needs
to understand the meanings of the terms used by the data
supplier . . . and if one want accuracy over a range of
topics, there is no alternative that I have seen to precise
logical descriptions of the terms that both parties have
access to. Precise logical descriptions of terms is the
function of the foundation ontology, and both communicating
parties need to use the same foundation ontology (of which
there could be more than one).
Yes, computers are tools and the tasks
for which they are properly equipped are becoming increasingly
sophisticated. For the task of communication among computer
systems that need to properly interpret the transmitted data,
some prior agreement on meaning is required, and a common
foundation ontology can provide that agreement over a broad
range of topics with the least effort. Otherwise one will
have probabilistic interpretations that will be suitable for
some applications, but too inaccurate for others.
On 2/7/14 3:53 PM, Patrick Cassidy
wrote:
There
is a serious problem with the suggested methodology:
> Two ontologies or vocabularies
(for instance FOAF and Schema.org) include definitions for
the same class (or kind) of entity e.g., an Organization,
> and as a consequence we end up
with Web accessible documents comprised of RDF
statements that describe Organizations as instances of
foaf:Organization or schemaorg:Organization.
>
> Challenge: How do we get a merged view of all the
organizations, irrespective of how they've been described
across various RDF documents?
>
> Solution:
>
> 1. Make a mapping/bridge/meta ontology that uses
owl:equivalentClass relations to indicate the fact
> that <http://xmlns.com/foaf/0.1/Organization>
and <http://schema.org/Organization>
are equivalent.
>
> 2. Load the mapping/bridge/meta ontology document
into a data management system that's capable
> of applying reasoning and
inference to the equivalence claim based on its
comprehension of the relation semantics expressed
>
> 3. Access instances of the <http://xmlns.com/foaf/0.1/Organization>
classes (e.g., by seeking a description
> of <http://xmlns.com/foaf/0.1/Organization>
which should produce a solution that includes subjects
> of instanceOf (rdf:type)
relations) -- and this will show a union of all instances
of across <http://xmlns.com/foaf/0.1/Organization>
and <http://schema.org/Organization>
>
> 4. Reverse the action in step 4 above -- the results
should be the same.
If
you create an equivalence mapping between entities in
independently developed ontologies and try to “reason”
with it in any but the most highly restricted manner,
you will almost certainly find unintended inferences,
likely logical inconsistency, and potentially a great
deal of gibberish. When you look at the logical
specifications of entities of the same name in different
ontologies, they are often quite different, even though
the intuition for the meanings may be similar. For
“organization”, for example, some ontologies have that
as a subtype of “group of people”. In some legal
jurisdictions, an Organization can exist without any
members – i.e., no people. That can lead to logical
contradictions if different definitions are equated. I
have never seen “process” defined the same way in any
two independent ontologies.
Yes, but nothing I've outlined contradicts the point you are
making.
My point is that you can opt to apply reasoning and
inference based on classes (entity types/kinds) described
across different ontologies. There is no such thing as one
ontology that rules all. What you can do is opt to apply
meta/bridge/mapping ontologies, according to your situation.
In my example, I am demonstrating how understanding of FOAF
and Schema.org classes can be used to integrate instances of
classes from either ontology. Note, I specifically include
examples with and without inference & reasoning to drive
home the point that is all loosely coupled i.e., its
application and use is a choice made by system user.
If
one only wants to create equivalencies and use that to
perform probabilistic or pattern-matching reasoning, that
may lead to useful results that can be helpful for the
humans who evaluate the results. But don’t expect the
kind of accuracy that would be needed to allow the
computers to make mission-critical decisions without human
intervention.
Computers cannot be left alone to mission-critical decisions
for humans. What they can do is perform a lot of the grunt
work that makes humans beings make better decisions, more
productively.
Or,
if one only wants to extract some one or two properties of
an entity (e.g. the director of a film), equating “film”
in two different ontologies may work as intended. But
extreme caution is advised.
Of course this has to be done with caution. I've never
perceived ontologies as a mechanism for making computers
perform tasks for which they are ill equipped.
Computers are tools, and when used properly, extremely
powerful productivity tools for humans.
Kingsley
Pat
Patrick
Cassidy
MICRA
Inc.
cassidy@xxxxxxxxx
1-908-561-3416
Kingsley, +1 ... Your
mapping/bridge/meta ontology is my "integrating
ontology". And, you captured the essence extremely well
in your demos.
2. Reasoning with the mappings
Clearly this works over data that
is Linked Data or data in ontologies.
On Fri, Feb 7, 2014 at 10:01 AM,
Kingsley Idehen <kidehen@xxxxxxxxxxxxxx>
wrote:
All,
Starting a new thread based on the theme above to
make what I am trying to demonstrate clearer.
Situation:
Schema.org [1] is a collaborative effort aimed as
simplifying structured data publication to the Web.
As part of this effort, a number of collaborators
have collectively produced a number of shared
vocabularies under the "schema.org"
namespace.
In addition to what's being produced by Schema.org
there are a thousands of shared ontologies and
vocabularies that have been constructed and
published to the Web from a plethora of sources,
many of these have been aggregated by services such
as LOV (Linked Open Vocabulary) [2] which is
basically accentuates the TBox and RBox aspects of
the Linked Open Data (LOD) Cloud.
Typical Integration Problem:
Two ontologies or vocabularies (for instance FOAF
and Schema.org) include definitions for the same
class (or kind) of entity e.g., an Organization, and
as a consequence we end up with Web accessible
documents comprised of RDF statements that describe
Organizations as instances of foaf:Organization or
schemaorg:Organization.
Challenge: How do we get a merged view of all the
organizations, irrespective of how they've been
described across various RDF documents?
Solution:
1. Make a mapping/bridge/meta ontology that uses
owl:equivalentClass relations to indicate the fact
that <http://xmlns.com/foaf/0.1/Organization>
and <http://schema.org/Organization>
are equivalent.
2. Load the mapping/bridge/meta ontology document
into a data management system that's capable of
applying reasoning and inference to the equivalence
claim based on its comprehension of the relation
semantics expressed
3. Access instances of the <http://xmlns.com/foaf/0.1/Organization>
classes (e.g., by seeking a description of <http://xmlns.com/foaf/0.1/Organization>
which should produce a solution that includes
subjects of instanceOf (rdf:type) relations) -- and
this will show a union of all instances of across
<http://xmlns.com/foaf/0.1/Organization>
and <http://schema.org/Organization>
4. Reverse the action in step 4 above -- the results
should be the same.
Live Demo Link:
[1] http://lod.openlinksw.com/describe/?url="">
-- description of <http://xmlns.com/foaf/0.1/Organization>
*without inference and reasoning enabled*, so the
relations presented are specific to the
aforementioned class.
[2] http://lod.openlinksw.com/describe/?url="">
-- description of <http://schema.org/Organization>
*without inference and reasoning enabled*, so the
relations presented are specific ot the
aforementioned class .
[3] http://lod.openlinksw.com/describe/?url="">
-- description of <http://xmlns.com/foaf/0.1/Organization>
*with inference and reasoning enabled*.
[4] http://lod.openlinksw.com/describe/?url="">
-- description of <http://schema.org/Organization>
with *inference and reasoning enabled*.
--
Regards,
Kingsley Idehen
Founder & CEO
OpenLink Software
Company Web: http://www.openlinksw.com
Personal Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter Profile: https://twitter.com/kidehen
Google+ Profile: https://plus.google.com/+KingsleyIdehen/about
LinkedIn Profile: http://www.linkedin.com/in/kidehen
_________________________________________________________________
Msg Archives: http://ontolog.cim3.net/forum/ontology-summit/
Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontology-summit/
Unsubscribe: mailto:ontology-summit-leave@xxxxxxxxxxxxxxxx
Community Files: http://ontolog.cim3.net/file/work/OntologySummit2014/
Community Wiki: http://ontolog.cim3.net/cgi-bin/wiki.pl?OntologySummit2014
Community Portal: http://ontolog.cim3.net/wiki/
_________________________________________________________________
Msg Archives: http://ontolog.cim3.net/forum/ontology-summit/
Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontology-summit/
Unsubscribe: mailto:ontology-summit-leave@xxxxxxxxxxxxxxxx
Community Files: http://ontolog.cim3.net/file/work/OntologySummit2014/
Community Wiki: http://ontolog.cim3.net/cgi-bin/wiki.pl?OntologySummit2014
Community Portal: http://ontolog.cim3.net/wiki/
--
Regards,
Kingsley Idehen
Founder & CEO
OpenLink Software
Company Web: http://www.openlinksw.com
Personal Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter Profile: https://twitter.com/kidehen
Google+ Profile: https://plus.google.com/+KingsleyIdehen/about
LinkedIn Profile: http://www.linkedin.com/in/kidehen