I was asked to prove p -> q |- ¬p or q by nature induction
- $p \rightarrow q$ premise
- p assume
- q $\rightarrow e,1$
- $¬ p \rightarrow ¬ q$
- ¬p assume
- ¬p or q or-i, 3-5
is it correct?
I was asked to prove p -> q |- ¬p or q by nature induction
is it correct?
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No
Where does (4) come from? And you haven't discharged your assumptions (2) and (5).
Hint: use a reductio proof -- i.e. assume $\neg(\neg p \lor q)$ and derive a contradiction ...