It's good that we separate the conceptual "layers" (views) from the
logical/representation levels. My understanding of HL7 RIM classes is
that they (at least classes like Observation) are meant to be
*subclassed* into more specific domain classes. Templates/archetypes
are constraints on (and hence describe subclasses of) these domain-
specific classes. Instances of patient-specific HbA1c observations are
also instances of Observation logically. HL7 experts among us can
correct me if I am wrong.
Samson
--
Samson Tu email: [EMAIL
PROTECTED]
Senior Research Scientist web:
www.stanford.edu/~swt/
Center for Biomedical Informatics Research phone: 1-650-725-3391
Stanford University fax:
1-650-725-7944
On Apr 22, 2008, at 1:07 PM, Elkin, Peter L., M.D. wrote:
Dear Vipul and Dan,
In order to not confuse the Ontology classification with First
Order / Second Order / Higher Order logics, we use Level 1
Ontologies to be domain independent (EAV just being a
representational mechanism for a logical system), level 2 Ontologies
are domain dependent (e.g. CDA), and level three contain defined
instances as well as class based definitions. We have been able to
make these distinctions work across multiple projects. If there is
a level zero I would suggest that Metaphysics or perhaps value
systems might be something that I have not seen well represented by
the upper level Ontologies with which I am familiar.
I believe we need a final single formal representational schema
where constructions defined across Information Models and
Terminological Models can be validated. This interlingua should be
defined from transforms from all other valid logical languages and
should empower all those SMEs familiar with any valid logical system
to work as they are comfortable. In the end, that work product must
be validated through the common interlingua to ensure that meaning
is preserved and therefore we are not creating unrecognized ambiguity.
With warm personal regards,
Peter
Peter L. Elkin, MD, FACP, FACMI
Professor of Medicine
Mayo Clinic College of Medicine
Baldwin 4B
Mayo Clinic
(507) 284-1551
fax: (507) 284-5370
From: Kashyap, Vipul [mailto:[EMAIL PROTECTED]
Sent: Tuesday, April 22, 2008 2:48 PM
To: [EMAIL PROTECTED]
Cc: Samson Tu; public-semweb-lifesci@w3.org; [EMAIL PROTECTED];
Elkin, Peter L., M.D.
Subject: Multi-layered Knowledge Representations for Healthcare (was
RE: An argument for bridging information models and ontologies at
the syntactic level)
Dan and Peter,
Based on conversations on this topic, there appears to be consensus
of the need for multi-layered knowledge representation schemes
for heatlhcare. Will be great if we could brainstorm and come to
some sort of consensus on these "layers". Would like to propose a
strawman as enumerated below.
Layer 0 = Entity - Attribute - Value or RDF triple based
rerpesentations.
Layer 1 = MetaClasses, e.g., Observation as in HL7/RIM
Layer 2 = Classes in a Patient Model, Document Models, etc, e.g.,
the class of HbA1c results for a class of Patients.
Layer 3 = Data that are instances of Classes, e.g., a particular
HbA1c result for a patient John...
As per your e-mail, you seem to be suggesting that there is
something in between Layer 1 and Layer 2. However, please note that
Layer 2 consists
of classes of assertions in the patient record and not instances.
More reespnses are embedded in the e-mail below.
<dan> With apologies to Peter in case I misrepresented your SOA
presentation...Last week, Peter Elkin of Mayo Clinic delivered a
presentation where he called the HL7 RIM a "first order ontology"
because of the abstraction level of the RIM. He called the models
derived from the RIM, e.g. analytic models, patient care document
models like CDA, etc, "second order ontology" because they add a
layer of concreteness to the abstractions of the RIM, i.e. an object
with classCode of observation and moodCode of order becomes an
"observation order object" with neither a classCode nor a moodCode.
[VK] Are there mathematical ways of describing these "derivations"
for e.g., by using operations such as instantiations and
generalizations/specializations.
Also, in the above, it's not clear what the semantics of an
"observation order" object is?
For e.g., observations and orders are semantically distinct
concepts, so in some sense an observation order class is likely to
be unsatisfiable?
The semantics of "moodCode" is not clear in Knowledge Representation
terms. For instance, do various mood codes partition the instances
of a class
into subclasses that are possbily mutually disjoint?
Finally, the coding systems themselves support the concreteness of
a "third order ontology." For example, the SNOMED concept becomes an
object itself without a code attribute, moodCode attribute, or
classCode attribute, e.g. a WBC order. />
[VK] One way of looking at a Snomed code is that it defines a class
(e.g., blood pressure) of all the instances of blood pressure
readings which would imply that it belongs to Layer 2 as defined
above?
<dan> see above for the "first order to third order model." Your
metaclass looks like Peter's "first order ontology." However, your
"instances" get introduced too early...your "instances" point to
actual medical record assertions, and Peter's model suggests that
there is more "in between." In Peter's model, the actual medical
record assertion would be an instance of his "third order
ontology." />
[VK] Agree. As per the layering introduced above, Layer 2 would
correspond to classes of assetions and Layer 3 would correspond to
actual instances or assertions.
<dan> I completely agree that the HL7 RIM is one level more
"concrete" than the earlier EAV models. The EAV model represents
the ultimate in abstraction, similar to RDF triples. Perhaps Peter
would be more correct to say that EAV is a "first order ontology"
and that the HL7 RIM is a "second order ontology." />
[VK] Agree: As per layering introduced abiove, The EAV/RDF
triples layer could be layer 0, and the HL7/RIM layer could be
layer 1
Look forward to further brainstorming and feedback on this.
Cheers,
---Vipul
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