eolas/Logic/Negation_Introduction.md
2022-04-23 18:30:04 +01:00

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---
tags:
- Logic
- propositional-logic
- derivation-rules
---
This is also known as *proof by contradiction*. You start with an assumption declared in a subproof. If you can derive a contradiction from this assumption (typically from the introduction of another proposition and its negation), then you are permitted to derive the negation of the auxiliary assumption in the main proof.
[]()![negate-intro 1.png](../img/negate-intro%201.png)