## Propositional Logic - Table of Contents | **`Title`** | **`Logic`** | **`Description`** | | | ------------ | ------------------ | ----------------------------------------- | --- | | [[Identity]] | P → P, ¬P → ¬P | A proposition is equal to itself. | | | [[Negation]] | ¬¬P ↔ P, ¬¬¬P ↔ ¬P | Double negations can be removed in pairs. | | | | | | | --- **`LeanNotes curator:`** [[dducoff]], [Contact dducoff](https://tally.so/r/rjQYWL) **`Posted Date`**: 2026-08-15