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Arepresents an association between two.
Eachis identified by a uniqueId and is distributed as a row in the Relationship file.
Acontainsof two logically associatedand theof anotherthat indicates theby which they are associated.
Table 1. Example: Defining arthritis as a type of joint disorder
In human readable terms...
Eachinis logically defined through itsto other.
Every(except the) has at least one |is a| to a supertype. |is a| and defining attributeare known as theof. They are considered defining because they are used to logically represent aby establishing itswith other. This is accomplished by establishing |Is a| with one or more defining(called supertypes) and modeling the difference with those supertypes through defining attributes.
Example: |Fracture of tarsal bone (disorder)| is defined as:
Note: Ais assigned only when thatis always known to be true.
Example: Group A Streptococcus causes most cases of Streptococcal pharyngitis. However, a small percentage of these cases are caused by other species of Streptococcus. Therefore, it would be incorrect to define |Streptococcal sore throat (disorder)| as having |causative agent| |Streptococcus pyogenes (organism)| . Instead it is correctly defined as having the more general |causative agent| |Genus Streptococcus (organism)| .
Figure 2. Example IS A hierarchy
Acan have more than one |is a| to other. In that case, thewill have parentin more than oneof a top-level.can be multi-hierarchical.
Figure 3. Example IS A Relationships
Anis an association between twothat specifies aof one of the(the source of the). Eachhas a name (the type of) and a value (the destination of the).
The combination of theand |is a| associated with arepresent the logical definition of that. Therefore, the logicaldefinition includes one or more supertypes (represented by |is a| ), and a set of definingthat differentiate it from the otherdefinitions.
The full definitions of the |Pneumonia (disorder)| ,|Infective pneumonia (disorder)| and |Bacterial pneumonia (disorder)| are shown below. Each line represents a definingwith a value.
Figure 4. Definition of |Pneumonia (disorder)|
Figure 5. Definition of |Infective pneumonia (disorder)|
Figure 6. Definition of |Bacterial pneumonia (disorder)|
Figure 7. Illustration of Defining Relationships