Professor Patrik Eklund of Umeå University, Department of Computing Science, in Sweden, sent us an email with the title, “SNOMED's logical foundation is too shallow for practical applications”.
We attempted to set up a meeting with Prof. Eklund, Daniel and Mikael (both Sewdish), Jim (Case) and myself (not so Swedish). However, Prof Eklund declined to participate in a meeting involving DL experts.
Below we provide the substance of the email, and documents pertaining to Prof. Eklund’s field of study [https://confluence.ihtsdotools.org/display/mag/SNOMED%27s+logical+foundation+is+too+shallow+for+practical+applications].
We would welcome your responses to Prof. Eklund’s comment and what they mean, if anything, fos SNOMED, and IHTSDO.
“Description Logic as the underlying logic for health terminology is not
sufficient. I think it is not not sufficient at all. This means that
SNOMED is not as useful in practice as it could be. I have access to
SNOMED through the Swedish Socialstyrelsen (The National Board of Health
and Welfare) licence, and over the years I failed to see how SNOMED is
useful in practice. I have discussed these issues also with
Socialstyrelsen at several occasions.
Needless, when we come down to guidelines, and logical representation of
evidence in guidelines, the underlying logical framework must be rich
and precise. Statistics only as the underlying computational machinery
for "evidence" in EBM is not enough. Such "evidence" is not evidence in
the sense of logic.
Since SNOMED adopted DL, very little has happened regarding SNOMED's
underlying conceptual model. When IHTSDO adopted DL as the logic for
SNOMED I was very surprised. Throughout many years I have often said
that "ontology" in "health ontology" cannot be the same as "ontology" in
"web ontology". "Ontology" in "health ontology" is more, and more
specific to health classification. I find it very unfortunate that
IHTSDO complies with a bivalent and untyped logic like DL.
One problem is indeed DL's bivalence, and its restriction to using
unstructured relations. The same goes obviously for its sibling methods
like FCA or Rough Sets. SNOMED's concepts mostly hide underlying
multivalence, e.g. as needed when mapping to a terminological scope like
the ICF. ICF's generic scale is nicely multivalent, even if the 'not
specified' isn't logically interpreted. It can be, but WHO has not made
Some say they have mapped SNOMED to ICF and vice versa, but these
mappings are very shallow constructions as they require to enforce ICF
into a DL framework using "is-a" as it is done in SNOMED. It is
basically just item mapping so that relations are preserved, and with
some ad hoc fine-tuning.
Bivalence can be easily extended to multivalence in SNOMED, but even
that is far from sufficient. The problem is still that "is-a" is a
relation basically over unstructured sets. It's also untyped in the
logical sense, and indeed, the underlying signature of DL is not a
signature (with sorts and operations) in the logical sense.
We have written several papers on this theoretical setting. Our
metalanguage is category theory, so our papers are probably a bit hard
to comprehend. However, we are developing practice based on our theory.
I am involved e.g. in information and process modelling within EIP AHA's
(European Innovation Partnership on Active and Healthy Ageing), so we
are continuously working with nomenclatures and classifications like WHO
classifications and potentially with SNOMED. EIP AHA's work on
assessment frameworks and upscaling is expected to benefit from these