# Overlap Similarity

Algorithm link: Approximate Nearest Neighbors

The **overlap coefficient**, or **Szymkiewicz–Simpson coefficient**, is a similarity measure
that measures the overlap between two finite sets.

\[{overlap} (X,Y)={\frac {|X\cap Y|}{\min(|X|,|Y|)}}\]

The algorithm takes two vectors denoted by `ListAccum`

and returns the
overlap coefficient between them.

## Notes

This algorithm is implemented as a user-defined function. You need to follow the steps in Add a User-Defined Function to add the function to GSQL. After adding the function, you can call it in any GSQL query in the same way as a built-in GSQL function.