eolas/Logic/Proofs/Negation_Introduction.md
2023-02-10 18:22:04 +00:00

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categories:
- Logic
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# Negation Introduction
This is also known as _proof by contradiction_. You start with an assumption declared in a sub-proof. 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.
![](/_img/negate-intro.png)