# Perles configuration

> system of 9 points and 9 lines in the Euclidean plane for which every combinatorially equivalent realization has at least one irrational number as one of its coordinates

**Wikidata**: [Q7169136](https://www.wikidata.org/wiki/Q7169136)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Perles_configuration)  
**Source**: https://4ort.xyz/entity/perles-configuration