negation of relation names

In the relations ontology we express:
eukaryotes consists of nucleus  ==> consists_of(eukaryotes, nucleus)
eurkaryotic cell enveloped by cell membrane ==> enveloped_by(cell, cell membrane)

as I am representing the school textbook, I find a few sentences to be of the form of negation. These are:

prokaryotes does not consist of nucleus ==> ~consists_of(prokaryotes, nucleus)
prokaryotes not enveloped by membrane  ==> ~enveloped_by(prokaryotes, membrane)

Such negations are useful for students to understand the difference between eukaryotes and prokaryotes and cannot be avoided during representation.

so my query is: can we include the negations of relation names in the relations ontology. how can we represent such negation relation names.

since ~consists_of, ~enveloped_by are negation of consists_of, enveloped_by respectively, does the relation names ~consists_of, ~enveloped_by still fall under the meronymic inclusion and spatial inclusion  respectively.

I think so.  In the above assertions, we know in reality that prokaryotes donot consists of nucleus, but this is equally important for representation. In cases such as something may cease to exist at a particular time t then we still have to represent such assertions even though these would be in negation forms.

But the question that is grappling my mind is the following:

ontology is the representation of types. it represents what exists in reality. now something that does not exist in reality, and yet if we want to represent it then would we still be creating ontology of non-existent entities. and if yes, then would it still be  ontology.

Perhaps, philosophers can  provide a convincing argument for my question.


4 Responses to negation of relation names

  1. gnowgi says:

    Given P is a proposition, ~P is the negation of the proposition. CG also takes care of this by negating a graph.

  2. There are actually a number of papers out about negation in ontologies: by Werner, and some more recent by Alan Rector (I think at last years OWLED).

  3. That information is very useful. Thanks Robert.

  4. I should also mention about the paper recommended by Werner: Ceusters W, Elkin P, Smith B. Negative Findings in Electronic Health Records and Biomedical Ontologies: A Realist Approach International Journal of Medical Informatics 2007;76:326-333

    This paper explains how negation relations can be represented in the form of “lacks”.

    prokaryotes lacks nucleus with respect
    to consists of at time t.

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