alexraasch
Reputation
Next privilege 250 Rep.
 Dec29 comment Proof of the Compactness Theorem for Propositional Logic I accepted your answer but I still don't get it. There are too many symbols to keep in my head at the same time. :) I'll keep trying. Dec29 comment Proof of the Compactness Theorem for Propositional Logic Ok, I have to admit your proof is too hard for me to digest. I think the basic idea is to say that every formula $\phi$ has only finitely many propositional variables. Let $n$ be that number. Then $\phi$ belongs to $S_n$, which has a model. So there is a model for every $\phi$ in $S$. Therefore, $S$ has a model. Dec29 comment Proof of the Compactness Theorem for Propositional Logic Sorry, I can't access the page you linked, none of the images are loaded due to some authorization error. Dec27 comment Proof of the Compactness Theorem for Propositional Logic In your 3rd paragraph, how do you decide if $T_1$ is infinite? Dec27 comment Proof of the Compactness Theorem for Propositional Logic Thanks, you're right. I read the FAQ after posting the question.