Proof theory

Affine logic Analytic proof Cirquent calculus Cointerpretability Contraction Cotolerant sequence Cut-elimination Deduction theorem Diagonal lemma Gentzen's consistency proof Gerhard Gentzen Interpretability logic Interpretability Intuitionistic linear logic Linear logic Ludics Metamathematics Nonfirstorderizability Proof net Proof-theoretic semantics Provability logic Relevant logic Reverse mathematics Self-verifying theories Sequent calculus Sequent Strict logic Structural proof theory Structural rule Substructural logics System F Tarski's undefinability theorem Tolerant sequence Weak interpretability Weakening