Editing Propositional calculus (section)

=== Natural deduction proof example ===
The proof below'''<ref name=":35" />''' derives <math>-P</math> from <math>P \to Q</math> and <math>-Q</math> using only '''MPP''' and '''RAA''', which shows that '''MTT''' is not a primitive rule, since it can be derived from those two other rules.
{| class="wikitable" style="margin:auto;"

|+ Derivation of MTT from MPP and RAA
|-
! Assumption set
! Line number
! Sentence of proof
! Annotation
|-
| {{EquationRef|1}}|| {{EquationRef|1}} || <math>P \to Q</math> || A
|-
| {{EquationRef|2}} || {{EquationRef|2}} || <math>-Q</math> || A
|-
| {{EquationRef|3}} || {{EquationRef|3}} || <math>P</math> || A
|-
| {{EquationRef|1}}, {{EquationRef|3}} || {{EquationRef|4}} || <math>Q</math> || {{EquationRef|1}}, {{EquationRef|3}} →E
|-
| {{EquationRef|1}}, {{EquationRef|2}} || {{EquationRef|5}} || <math>-P</math> || {{EquationRef|2}}, {{EquationRef|4}} RAA
|}