# Compound Expression 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
19829001 |Disorder of lung| descendants and the set of
301867009 |Edema of trunk| descendants.

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

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 19829001 |Disorder of lung| descendants and the set of 301867009 |Edema of trunk| descendants. For this reason, an

*OR*operator will usually allow more valid clinical meanings than an

*AND*operator.

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

This expression constraint is satisfied only by concepts that belong to the 19829001 |Disorder of lung| hierarchy

*and*are also members of the 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:

^ 700043003 |Example problem list concepts reference set|

^ 700043003 |Example problem list concepts reference set|

^ 700043003 |Example problem list concepts reference set| )

**valid:**

*not*

^ 700043003 |Example problem list concepts reference set|

^ 700043003 |Example problem list concepts reference set|

^ 700043003 |Example problem list concepts reference set| )

# Attribute Conjunction and Disjunction

Conjunction and disjunction may be used within refinements in a variety of ways. The most common way of using these operators in a refinement is to define the conjunction or disjunction of individual attributes.

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).

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| ,

116676008 |Associated morphology| = << 415582006 |Stenosis|

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis|

*either*an associated morphology of 'infarct' (or subtype)

*or*are due to a myocardial infarction (or subtype).

116676008 |Associated morphology| = << 55641003 |Infarct| OR

42752001 |Due to| = << 22298006 |Myocardial infarction|

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| AND

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

( 363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| ) AND

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

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:

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| OR

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

( 363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| ) OR

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

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).

{ 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.

246075003 |Causative agent| = (< 373873005 |Pharmaceutical / biologic product| OR < 105590001 |Substance| )

*both*a subtype (or self) of ulcer

*and*a subtype (or self) of hemorrhage.

(<< 56208002 |Ulcer| AND << 50960005 |Hemorrhage| )

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