Disclaimer: I'm a complete newbie to the site, and I haven't fully figured out how to format properly. I do not have enough reputation to use the meta sandbox thread, so in addition to asking my question, I may use some space below to test some stuff out...
edit: I now have enough reputation to use the meta forums
Here's what I've done so far, with regards to the question:
- $p ⇒ q$ (premise)
- (tab)|$¬q$ (assumption)
- (tab)| (tab) |$p$ (assumption)
- (tab)| (tab) |$¬q$ (reiteration: 2)
- (tab)|$p ⇒ ¬q$ (implication introduction: 3, 4)
- (tab)|$¬p$ (negation introduction: 1,5)
I thought of "Or-ing" $¬p$ with $q$ (Or introduction: 6) but that would not be a complete proof, because I would still be within a subproof. What steps am I missing? Or, perhaps, was I going in the wrong direction in the first place?
Also, please do not edit the format of my question. Instead, I would appreciate formatting suggestions, especially including the following:
- how do I format a tab?
- how do I format logic symbols like "and"/"or", without using copy+paste.
- how do I format Fitch-style logic problems. I don't want to use "|" as a substitute for the solid line going down.