# PH

> algorithmic complexity class; the union of all complexity classes in the polynomial hierarchy; the set of languages expressible by second-order logic

**Wikidata**: [Q1063380](https://www.wikidata.org/wiki/Q1063380)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/PH_(complexity))  
**Source**: https://4ort.xyz/entity/ph-q1063380


## References

1. Freebase Data Dumps. 2013
2. BabelNet
3. [OpenAlex](https://docs.openalex.org/download-snapshot/snapshot-data-format)