We present a formalization of parts of Melvin Fitting's book "First-Order Logic and Automated Theorem Proving". The formalization covers the syntax of first-order logic, its semantics, the model existence theorem, a natural deduction proof calculus together with a proof of correctness and completeness, as well as the Löwenheim-Skolem theorem.BSD License
[2018-07-21] Proved completeness theorem for open formulas. Proofs are now written in the declarative style. Enumeration of pairs and datatypes is automated using the Countable theory.