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# Constraints

Expression constraints can be built up from smaller parts using conjunction (i.e. AND) and disjunction (i.e. OR). The simplest example of this is where the conjunction or disjunction is used between two simple expressions. For example, the following expression constraint is satisfied only by clinical findings which are both a disorder of the lung and an edema of the trunk. This gives the same result as a mathematical intersection between the set of

term
Scg expression
ShowParts
Concept
t 19829001|Disorder
 of
 lung|
descendants and the set of
Scg expression
Concept
t
ShowPartsterm
 301867009|Edema
 of
 trunk|
descendants.

Scg expression
Border ridge block
`   < 19829001 |Disorder of lung| AND < 301867009 |Edema of trunk|`

Please note that all keywords are case insensitive, so the following two expression constraints are equivalent to the above:

Scg expression
Border ridge block
`   < 19829001 |Disorder of lung| and < 301867009 |Edema of trunk|`

Scg expression
Border ridge block
`   < 19829001 |Disorder of lung| And < 301867009 |Edema of trunk|`

The next expression constraint is satisfied only by clinical findings which are either a disorder of the lung or an edema of the trunk. This gives the same result as a mathematical union of the set of

ridge
Scg expression
ShowPartsterm
Border
Concept
t 19829001|Disorder
 of
 lung|
descendants and the set of scg-expression
Concept
ShowParts term ridge
t 301867009|Edema
 of
 trunk|
descendants. For this reason, an OR operator will usually allow more valid clinical meanings than an AND operator.

Scg expression
Border ridge block
`  < 19829001 |Disorder of lung| OR < 301867009 |Edema of trunk|`

Conjunction and disjunction operators may also be combined with the use of the 'member of' function, as shown below:

Scg expression
Border ridge block
`   < 19829001|Disorder of lung| AND ^ 700043003 |Example problem list concepts reference set|`

This expression constraint is satisfied only by concepts that belong to the

ridge
Scg expression
ShowPartsterm
Border
Concept
t 19829001|Disorder
 of
 lung|
hierarchy and are also members of the scg-expression
Concept
ShowParts term ridge
t 700043003|Example
 problem
 list
 concepts
 reference
 set|
.

When more than one conjunction or more than one disjunction is used, round brackets can be optionally applied. For example, the following expression constraints are all valid and equivalent to each other:

Scg expression
Border ridge block
```   < 19829001 |Disorder of lung| AND < 301867009 |Edema of trunk| AND
^ 700043003 |Example problem list concepts reference set|```

Scg expression
Border ridge block
```   (< 19829001 |Disorder of lung| AND < 301867009 |Edema of trunk|) AND
^ 700043003 |Example problem list concepts reference set|```

...

However, where a conjunction and disjunction are both used together, it is mandatory to use round brackets to disambiguate the meaning of the expression constraint. For example, the following expression constraint is not valid:

Scg expression
Border ridge block
```   < 19829001 |Disorder of lung| AND < 301867009 |Edema of trunk| OR
^ 700043003 |Example problem list concepts reference set|```

And must be expressed (depending on the intended meaning) as either:

Scg expression
Border ridge block
```   (< 19829001 |Disorder of lung| AND < 301867009 |Edema of trunk|) OR
^ 700043003 |Example problem list concepts reference set|```

Or as:

Scg expression
Border ridge block
```   < 19829001 |Disorder of lung| AND (< 301867009 |Edema of trunk| OR
^ 700043003 |Example problem list concepts reference set|)```

# Attribute Conjunction and Disjunction

...

For example, the expression constraint below, in which the comma between the two attributes represents conjunction, is satisfied only by clinical findings which have both a finding site of pulmonary valve structure (or subtype) and an associated morphology of stenosis (or subtype).

Scg expression
Border ridge block
```   < 404684003 |Clinical finding|:
363698007 |Finding site| = << 39057004 |Pulmonary valve structure|,
116676008 |Associated morphology| = << 415582006 |Stenosis|```

This expression constraint can equivalently be expressed as:

Scg expression
Border ridge block
```   < 404684003 |Clinical finding|:
363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND
116676008 |Associated morphology| = << 415582006 |Stenosis|```

The following example uses the disjunction operator (OR) to represent the disjunction of two attributes. This constraint is satisfied only by clinical findings which have either an associated morphology of 'infarct' (or subtype) or are due to a myocardial infarction (or subtype).

Scg expression
Border ridge block
```   < 404684003 |Clinical finding|:
116676008 |Associated morphology| = << 55641003 |Infarct| OR
42752001 |Due to| = << 22298006 |Myocardial infarction|```

When more than one conjunction or more than one disjunction is used in a refinement, round brackets can be optionally applied. For example, the following expression constraints are all valid and equivalent to each other:

Scg expression
Border ridge block
```   < 404684003 |Clinical finding|:
363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND
116676008 |Associated morphology| = << 415582006 |Stenosis| AND
42752001 |Due to| = << 445238008|Malignant carcinoid tumor|```

Scg expression
Border ridge block
```   < 404684003 |Clinical finding|:
(363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND
116676008 |Associated morphology| = << 415582006 |Stenosis| ) AND
42752001 |Due to| = << 445238008|Malignant carcinoid tumor|```

...

For example, the following expression constraint is not valid:

Scg expression
Border ridge block
```   < 404684003 |Clinical finding| :
363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND
116676008 |Associated morphology| = << 415582006 |Stenosis| OR
42752001 |Due to| = << 445238008|Malignant carcinoid tumor|```

And must be expressed (depending on the intended meaning) as either:

Scg expression
Border ridge block
```   < 404684003 |Clinical finding| :
(363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND
116676008 |Associated morphology| = << 415582006 |Stenosis|) OR
42752001 |Due to| = << 445238008|Malignant carcinoid tumor|```

Or as:

Scg expression
Border ridge block
```   < 404684003 |Clinical finding| :
363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND
(116676008 |Associated morphology| = << 415582006 |Stenosis| OR
42752001 |Due to| = << 445238008|Malignant carcinoid tumor| )```

# Attribute Group Conjunction and Disjunction

Similarly, conjunction and disjunction may be defined between attribute groups. The following expression constraint is satisfied only by clinical findings which either have a finding site of pulmonary valve structure (or subtype) and an associated morphology of stenosis (or subtype), OR have a finding site of right ventricular structure (or subtype) and an associated morphology of hypertrophy (or subtype).

Scg expression
Border ridge block
```   < 404684003 |Clinical finding|:
{363698007 |Finding site| = << 39057004 |Pulmonary valve structure|,
116676008 |Associated morphology| = << 415582006 |Stenosis|} OR
{363698007 |Finding site| = << 53085002 |Right ventricular structure|,
116676008 |Associated morphology| = << 56246009 |Hypertrophy|}```

# Attribute Value Conjunction and Disjunction

Conjunction and disjunction can also be applied to attribute values. The example below is satisfied only by members of the adverse drug reactions reference set for GP/FP health issue, which have a causative agent that is either a subtype of pharmaceutical / biologic product or a subtype of substance.

Scg expression
Border ridge block
```   ^ 450990004 |Adverse drug reactions reference set for GP/FP health issue|:
246075003 |Causative agent| = (< 373873005 |Pharmaceutical / biologic product| OR < 105590001 |Substance|)```

Similarly, attribute values can also use conjunction. The following expression constraint is satisfied only by clinical findings with an associated morphology whose value is both a subtype (or self) of ulcer and a subtype (or self) of hemorrhage.

Scg expression
Border ridge block
```   < 404684003 |Clinical finding|: 116676008 |Associated morphology| =
(<< 56208002|Ulcer| AND << 50960005|Hemorrhage|)```

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