---
tag: AQ8G5BKDN1
kind: concept
name: Boldface
sources:
  - wikipedia: en:43580500@r1360947732
    locator: Glossary of set theory, section B
    note: adopted
    mention: wikipedia://en/43580500#QAFY
    sections: [Summary]
inventory: [FP3YCD9RHP]
---

## Summary

The boldface hierarchy is a hierarchy of subsets of a Polish space, definable by second-order formulas with parameters (as opposed to the lightface hierarchy which does not allow parameters). It includes the Borel sets, analytic sets, and projective sets