I just need to show somebody that it is trivial, and already well known, that from ~(A -> B) you can prove A. Long story. Yes, I’m talking to a crank.
The best way for me to do this would be to be able to show how this is literally a beginner’s exercise in some beginning logic book somewhere.
I searched the one I happen to have on hand and came up short. Anyone able to supply a page citation for a book that has this proof either as an example or exercise? Talking specifically about a low-level propositional logic textbook.