New posts in Proof Theory

Natural Deduction Proof for Modus Tollens

Understanding ex falso quodlibet together with proof by contradiction in a Gentzen style ND Proof

Why does Gödel's Second Incompleteness Theorem undermine Hilbert's program?

Has a conjecture ever originally been decided by constructing the proof with mathematical logic?

Trouble understanding proof to $\vdash ((\neg(\phi\rightarrow \psi))\rightarrow\phi)$?

Predicate Logic, Proof of validity . How to remove negation infront of existential quantifier?

Curry-Howard for an imperative programming language?

Why does proof by elimination work?

Comma in turnstile (entailment)

Is this proof correct? (natural deduction)