# Paris–Harrington theorem

> certain principle in Ramsey theory is true, but not provable in Peano arithmetic

**Wikidata**: [Q7137494](https://www.wikidata.org/wiki/Q7137494)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Paris–Harrington_theorem)  
**Source**: https://4ort.xyz/entity/paris-harrington-theorem