---
tag: YP1F936PJ0
kind: concept
name: Extensional function
sources:
  - wikipedia: en:43839113@r1368323132
    locator: Glossary of Principia Mathematica, section Glossary
    note: adopted
    mention: wikipedia://en/43839113#NGYL
    sections: [Summary]
inventory: [V7N9KW905F]
---

## Summary

A function whose value does not change if one of its arguments is changed to something equivalent.