Rule of Implication/Sequent Form/Proof 1
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Theorem
The Rule of Implication can be symbolised by the sequent:
\(\ds \paren {p \vdash q}\) | \(\) | \(\ds \) | ||||||||||||
\(\ds \vdash \ \ \) | \(\ds p \implies q\) | \(\) | \(\ds \) |
Proof
By the tableau method of natural deduction:
Line | Pool | Formula | Rule | Depends upon | Notes | |
---|---|---|---|---|---|---|
1 | 1 | $p$ | Premise | (None) | ||
2 | 1 | $q$ | By hypothesis | 1 | as $p \vdash q$ | |
3 | 1 | $p \implies q$ | Rule of Implication: $\implies \II$ | 1 – 2 | Assumption 1 has been discharged |
$\blacksquare$