Some facts and definitions about propositional and predicate extensionality
We investigate the relations between the following extensionality principles
- Proposition extensionality
- Predicate extensionality
- Propositional functional extensionality
- Provable-proposition extensionality
- Refutable-proposition extensionality
- Extensional proposition representatives
- Extensional predicate representatives
- Extensional propositional function representatives
Table of contents
1. Definitions
2.1 Predicate extensionality <-> Proposition extensionality + Propositional functional extensionality
2.2 Propositional extensionality -> Provable propositional extensionality
2.3 Propositional extensionality -> Refutable propositional extensionality