> For the complete documentation index, see [llms.txt](https://docs.wem.io/platform/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.wem.io/platform/wemreference/functions/concepts/intersection.md).

# Intersection

{% hint style="info" %}
The **`Intersection()`** function produces a concept set that contains the concepts that a part of all given concept sets in the parameters.

[*Read general information about Concepts and Ontology*](/platform/wemmodeler/concepts-and-concept-queries/concepts.md)

This function is NOT SQL compatible. For more information about SQL compatibility, see our [documentation](/platform/wemreference/sql-compatibility.md).
{% endhint %}

{% hint style="success" %}
Returns a concept set with the concepts that occur in each concept set provided in the parameter list.

An <mark style="color:red;">unknownconceptset</mark> value is returned if any of the conceptsets in the list is unknown, or if there is no concept available in all sets in the parameterlist.
{% endhint %}

### Syntax

<details>

<summary><code>Intersection( List(</code><mark style="color:blue;"><code>concept_set_1, concept_set_2, ...</code></mark><code>) )</code></summary>

`Intersection( List([AllColors], 'Color'.'Purple') )`\
\=>*Result: { Purple } (as a conceptset with one concept)*

`Intersection( List( [AllColors], {'Color'.'Amber', 'Color'.'Teal'}) )`\
\=>*Result: { Amber, Teal }*

`Intersection( List( [AllColors], [EMEA-Regions]) )`\
\=>*Result: unknownconceptset*

`Intersection( List(unknownconceptset, [AllColors]) )`\
\=>*Result: unknownconceptset*

</details>

### Parameters

<table><thead><tr><th width="193.2224596298586">Name</th><th width="150">Type</th><th width="150" align="center">Required</th><th width="248.15953250810662">Description</th><th data-hidden>Required?</th></tr></thead><tbody><tr><td><mark style="color:blue;"><code>concept_set_x</code></mark></td><td>list of concepts</td><td align="center"><span data-gb-custom-inline data-tag="emoji" data-code="2611">☑️</span></td><td>2 or more sets of concepts (or a single concept) combined with the List() function as parameterlist.</td><td>yes</td></tr></tbody></table>


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