Rule of Addition/Sequent Form/Form 2/Proof 1
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Theorem
- $q \vdash p \lor q$
Proof
By the tableau method of natural deduction:
Line | Pool | Formula | Rule | Depends upon | Notes | |
---|---|---|---|---|---|---|
1 | 1 | $q$ | Premise | (None) | ||
2 | 1 | $p \lor q$ | Rule of Addition: $\lor \II_2$ | 1 |
$\blacksquare$
Sources
- 1965: E.J. Lemmon: Beginning Logic ... (previous) ... (next): Chapter $1$: The Propositional Calculus $1$: $3$ Conjunction and Disjunction: Exercise $1 \ \text{(d)}$