Assertions

The  of  consists of one or more assertions made by . 

Necessary Conditions

Each time an assertion is made about a concept, an  must decide if that assertion is a .  If the assertion is always true for that concept and its , it is a .

• This implies that for all instances of that concept or its subtypes, the assertion must be true, even if it has not been explicitly stated.

Sufficient Definitions

For each  an  must decide if there are one or more sets of assertions that form a  of that concept. A set of assertions is a  if it distinguishes a  and its subtypes from other concepts. 

• This implies that if all assertions in the set are true for a concept, it must be an instance of the defined concept or a subtype of that concept.

Concepts with no Sufficient Definitions

A  that has no  is a . 

Because  have no  it is not possible for a  to determine if other concepts are  of this concept. Similarly, it is not possible to automatically determine whether an expression is a subtype of a primitive concept. Therefore, only concepts or expressions that explicitly state they are subtypes of primitive concepts will be treated as subtypes when applying expression constraints or undertaking analysis. 

However, note that this does not prevent a  being classified as a subtype of a . 

Concepts with a Sufficient Definition

A  that has at least one  is a . 

A  can determine whether the stated definitions of other concepts meet at least one of the  and if so will classify these concepts as its . Similarly, it is possible to determine whether an expression is equivalent to or a subtype of a . Therefore, where expression constraints or queries refer to  the results will include the inferred subtypes of these concepts.

Sufficiently Defined Concepts with Necessary Conditions

If a  has one or more additional  then any concept or expression that satisfies one of its  will also inherit any .

For example one sufficient definition of is an ulcer in a stomach structure:

=== 64572001 |disease| : { 116676008 |associated morphology| = 56208002 |ulcer| , 
	    363698007 |finding site| = 69695003 |stomach structure| }

However, another definition could be created with a more specific site gastric mucosa:

=== 64572001 |disease|: { 116676008 |associated morphology| = 56208002 |ulcer| , 
	    363698007 |finding site| = 78653002|gastric mucosa| }

In both cases these definition are equivalent to . The more general definition is flexible when it comes to allowing refinement to a specific location of the ulcer within the stomach, which is actually useful information. It also avoids requiring an expression to refer specifically to the mucosa (stomach lining), which is where all gastric ulcers occur.

For example, an expression including the specific location could look like this

=== 64572001 |disease| : { 116676008 |associated morphology| = 56208002 |ulcer| , 
	    363698007 |finding site| = 127869006 |Anterior wall of fundus of stomach| }

This satisfies the sufficient definition because the finding site is a subtype of stomach structure. This will therefore classify as a type of  located in the anterior wall of the gastric fundus. The problem is that a query for disorders of the gastric mucosa will not find this expression.

<< 64572001 |disease|: 363698007 |finding site| = 78653002|gastric mucosa|

However, adding the definition that refers to the gastric mucosa as an additional  can solve this problem. The expression satisfies the  implying this is a type of . The fact that it is a type of gastric ulcer causes it to inherit  so it will now be included in the query for disease in the gastric mucosa.