# Hadwiger–Nelson problem

> mathematical problem

**Wikidata**: [Q1383936](https://www.wikidata.org/wiki/Q1383936)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Hadwiger–Nelson_problem)  
**Source**: https://4ort.xyz/entity/hadwiger-nelson-problem


## References

1. Freebase Data Dumps. 2013