Double Negation/Double Negation Introduction/Proof Rule/Tableau Form
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Proof Rule
Let $\phi$ be a well-formed formula in a tableau proof.
Double Negation Introduction is invoked for $\phi$ as follows:
Pool: | The pooled assumptions of $\phi$ | ||||||||
Formula: | $\neg \neg \phi$ | ||||||||
Description: | Double Negation Introduction | ||||||||
Depends on: | The line containing the instance of $\phi$ | ||||||||
Abbreviation: | $\text{DNI}$ or $\neg \neg \II$ |