Robert,
ISO 1087-1 and ISO 704, which are standards for creating vocabularies and definitions (and did not arise from a formal logic community), specify two mechanisms
for defining a ‘concept’ or ‘class’:
1) identify a more general concept and the delimiting characteristics of the subordinate concept being defined
This is exactly: An A is a B that C.
2) identify a list of subordinate concepts that together cover the more general concept being defined – the union of other defined classes:
An A is a B or a C or a D.
One can also define a Class as the intersection of two or more classes, but that is just a special case of (1): An A is a B that is also a C.
I’m not aware of any others.
-Ed
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To: [ontolog-forum]
Subject: [ontolog-forum] Types of Formal (logical) Definitions in ontology
1) How many types of formal (logical) definitions of terms/classes do you know of?
For example, a term can be defined in a genus-species form:
An A is a B that C.
What others do you know of?
2) For ontologies, are there non-FOL definitions?
Are there definitions not based on syllogistic logic?
3) And what are the pro's and con's of each?