LOGIC

This second edition improves upon the first by offering a more detailed treatment of key topics and by expanding the set of problems and exercises. In particular, four new features deserve mention. First, the book now includes a more thorough exposition of natural deduction, explaining how derivations can be represented as trees of formulas. Second, it provides a detailed explanation of the main proof methods, illustrated with examples. Third, it offers a separate exposition of the logic of identity. Fourth, it presents a fuller treatment of modal logic, including results on consistency, soundness, and completeness. Additional changes include new examples drawn from elementary mathematics, a refined notation, and a more functional subdivision of the material, which simplifies some proofs and enhances clarity and readability. Overall, the text preserves the style of the first edition, aiming to present core ideas clearly, concisely, and with minimal distractions.