Modus Tollendo Ponens/Proof Rule/Tableau Form

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Proof Rule

Let $\phi \lor \psi$ be a well-formed formula in a tableau proof whose main connective is the disjunction operator.

The Modus Tollendo Ponens is invoked for $\phi \lor \psi$ in either of the two forms:


Form 1
Pool:    The pooled assumptions of $\phi \lor \psi$      
The pooled assumptions of $\neg \phi$      
Formula:    $\psi$      
Description:    Modus Tollendo Ponens      
Depends on:    The line containing the instance of $\phi \lor \psi$      
The line containing the instance of $\neg \phi$      
Abbreviation:    $\text{MTP}_1$      


Form 2
Pool:    The pooled assumptions of $\phi \lor \psi$      
The pooled assumptions of $\neg \psi$      
Formula:    $\phi$      
Description:    Modus Tollendo Ponens      
Depends on:    The line containing the instance of $\phi \lor \psi$      
The line containing the instance of $\neg \psi$      
Abbreviation:    $\text{MTP}_2$