eolas/Logic/Negation_Elimination.md

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2022-04-23 13:26:53 +01:00
---
tags:
- Logic
- propositional-logic
- derivation-rules
---
![negate-elim 1.png](../img/negate-elim%201.png)
Like the [introduction](Negation%20Elimination.md) rule for negation, the elimination rule also works by deriving a contradiction. It is basically *Negation Introduction* in reverse. Instead of starting the subproof with a true proposition from which you derive a contradiction, you start with the negation of a proposition, derive a contradiction and then assert the positive of the negated proposition you started out with.