Libro: forall x: Calgary: An Introduction to Formal Logic

An introduction to formal logic, covering truth-functional (propositional) and first-order (predicate) logic. It deals with logical notions such as entailment and satisfiablity, symbolization of English sentences using connectives and quantifiers (including identity, e.g., definite descriptions), the semantics of TFL (truth tables) and FOL (first-order interpretations), and proofs (using a Fitch-style natural deduction system). Advanced topics discussed are the truth-functional completeness of propositional logic, normal forms, the soundness of the proof system, and the basics of modal logic. Available for free download at forallx.openlogicproject.org.